Obesity Care

Prolonged obesity in early life linked to accelerated biological ageing, study finds

Key Takeaways:

• Individuals with persistent obesity from early childhood or adolescence show signs of biological ageing years ahead of their chronological age.
• Researchers observed increases of over 4.5 years in biological age and up to 48% acceleration in some individuals, alongside molecular markers of physiological decline.
• Findings challenge the long-standing belief that calorie restriction is the key modulator of ageing, suggesting instead that obesity itself may drive premature ageing.
  

Introduction: Obesity and Ageing – Rethinking the Relationship

New research from the Santiago Longitudinal Study has found that individuals with long-term obesity exhibit signs of accelerated biological ageing as early as their late twenties. The findings, published in JAMA Network Open, provide compelling evidence that sustained obesity from childhood or adolescence may hasten physiological decline at a molecular level – in some cases by nearly five years compared to chronological age. 

The results pose a significant challenge to traditional models of ageing, which have focused heavily on the benefits of caloric restriction. Instead, the authors argue that excess calorie intake and the associated hormonal and metabolic changes of obesity may directly contribute to the ageing process.

Study Overview: A Longitudinal View of Lifespan Health

The research team, led by Dr Paulina Correa-Burrows of the Universidad de Chile, drew on data from over 1,000 participants in the Santiago Longitudinal Study, a project tracking individuals from birth through to young adulthood. For this analysis, the focus was narrowed to 205 participants with complete data sets:

• 89 individuals with a normal body mass index (BMI)
• 43 individuals with obesity beginning in adolescence
• 73 individuals with obesity starting in early childhood
  

Participants were followed until they reached the ages of 28 to 31 years, at which point a range of biological ageing markers were assessed.

Biological Ageing Measured by Epigenetic Clocks

To estimate biological age, researchers used multiple advanced methods, including:

• DNA methylation-based epigenetic clocks
• Estimation of leukocyte telomere length
• Circulating biomarkers such as cytokines, adipokines, myokines, and growth factors
  

The findings were stark. In participants with long-term obesity, epigenetic age exceeded chronological age by:

• 2.23 to 4.68 years, depending on the method used
• 15.2% to 16.4% increase on average
• Up to 48% in some individuals
  

These results suggest that long-term obesity may induce molecular signatures typically associated with ageing, including telomere shortening, mitochondrial stress, chronic inflammation, and disrupted intercellular signalling.

Rethinking the Role of Calories in Ageing

In an editorial accompanying the study, Dr Antonello Lorenzini reflects on the broader implications of these findings. Historically, the biology of ageing has centred on the notion that caloric restriction slows ageing. However, Dr Lorenzini proposes a paradigm shift:

“The average level of biological age is clearly elevated in the two groups experiencing lasting obesity,” he wrote.

“This elevation strongly suggests that it is time to doubt the classical interpretation that has dominated the field of biology of aging for a long time: caloric restriction slows down the aging process.”

He suggests that the presence of excess calories, the hormonal imbalance of obesity, or both, may serve as active drivers of ageing.

Implications for Public Health and Ageing Research

Dr Lorenzini also highlights the public health implications of these findings, particularly given the scale of the global obesity epidemic:

“A new awareness of the effect of obesity in accelerating the aging process represents an additional element for educational campaigns that aim to address the globesity epidemic,” he wrote.

Rather than advocating for restrictive diets or prolonged hunger, Dr Lorenzini suggests a more balanced approach to healthy ageing:

“The recipe for a long and healthy life, therefore, does not seem to require experiencing hunger, but rather simply avoiding mental and physical stress, getting an appropriate amount of physical activity, and modifying the diet to increase foods that prevent obesity while reducing those that promote it.”

Conclusion

This study adds to a growing body of evidence linking long-term obesity with premature biological ageing. While more research is needed to establish causal mechanisms and explore potential interventions, the findings underscore the importance of early-life obesity prevention and raise critical questions about how we understand and modulate the ageing process.

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Obesity-linked cancer deaths triple across the United States over two decades, study finds

Key Takeaways:

• Cancer deaths associated with obesity have tripled in the United States from 1999 to 2020, with the sharpest rises seen among women, older adults, Black people, Native Americans and those living in rural communities.
• Obesity is linked to a higher risk of developing 13 types of cancer, which collectively account for 40% of all cancers diagnosed in the United States each year.
• Researchers highlight the urgent need for tailored public health initiatives to enhance early screening and expand access to care, particularly in underserved and high-risk areas.
  

Alarming rise in obesity-related cancer deaths

Cancer deaths linked to obesity have tripled in the United States over the past two decades, according to new research being presented at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco, California.

The study investigated more than 33,000 deaths from cancers known to be associated with obesity. It revealed striking increases in mortality, particularly among women, older adults, Native Americans and Black Americans.

“Obesity is a significant risk factor for multiple cancers, contributing to significant mortality. This research underscores the need for targeted public health strategies such as early screening and improved access to care, especially in high-risk rural and underserved areas,” said Dr Faizan Ahmed, lead researcher from Hackensack Meridian Jersey Shore University Medical Center in Neptune City, New Jersey.

Obesity’s far-reaching impact on health

Obesity is a widespread condition. According to the U.S. Centers for Disease Control and Prevention (CDC), 40.3% of adults in the country have obesity. It is a complex disease, influenced by an interplay of genetic, physiological, hormonal, environmental and developmental factors.

In addition to increasing the risk of certain cancers, obesity raises the likelihood of developing serious long-term conditions, including:

• high blood pressure
• high cholesterol
• prediabetes and type 2 diabetes
• heart disease
• chronic and end-stage kidney disease
  

The 13 cancers linked to obesity

Data from the CDC show that obesity is associated with a higher risk of developing 13 types of cancer. These cancers together make up 40% of all cancers diagnosed each year in the United States. They include:

• Adenocarcinoma of the oesophagus
• Breast cancer (in women who have gone through menopause)
• Colon and rectal cancer
• Cancer of the uterus
• Gallbladder cancer
• Upper stomach (gastric cardia) cancer
• Kidney cancer
• Liver cancer
• Ovarian cancer
• Pancreatic cancer
• Thyroid cancer
• Meningioma (a type of brain tumour)
• Multiple myeloma
  

What the study found

Dr Ahmed’s research used mortality data from the CDC to analyse 33,572 deaths in the United States from cancers linked to obesity between 1999 and 2020. The findings showed that age-adjusted mortality rates rose markedly over this period, increasing from 3.73 to 13.52 per million people.

Certain groups experienced especially steep rises in these death rates. These included:

• women
• older adults
• Black people
• Native Americans
• people living in rural areas
  

Regional differences across the United States

The study also uncovered notable geographic patterns. The Midwest recorded the highest rate of obesity-related cancer deaths, whereas the Northeast had the lowest. When analysed by state, Vermont, Minnesota and Oklahoma had the highest rates of deaths linked to obesity-associated cancers. In contrast, Utah, Alabama and Virginia reported the lowest rates.

Calls for stronger public health action

Experts stress that these findings highlight the critical importance of targeted public health interventions. Strategies could include expanding early cancer screening programmes and improving access to healthcare services, with a particular focus on communities that are rural, socioeconomically disadvantaged or have a high prevalence of obesity.

As Dr Ahmed emphasised: “This research underscores the need for targeted public health strategies such as early screening and improved access to care, especially in high-risk rural and underserved areas.”

CCH Insight:

Sadly, the rapid rise in cancer cases across the US is not really surprising, in that it follows the increase in obesity over recent decades. While CCH agrees there is an urgent need for targeted public health strategies, such as early cancer screening and improved access to cancer care, we would also say “treat obesity first.” If you treat obesity successfully, you will significantly reduce the prevalence of obesity-related conditions such as type 2 diabetes, heart disease and a number of common cancers.

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Intermittent fasting shown to be effective for weight loss in new large-scale study

Key Takeaways:

• A comprehensive analysis of 99 clinical trials found alternate-day fasting to be the most effective form of intermittent fasting for weight loss and improving key health markers.
• Participants practising alternate-day fasting lost an average of 1.3 kg more than those following standard calorie-restricted diets, alongside improvements in waist size, cholesterol, and inflammation.
• However, the differences fell below the threshold considered clinically meaningful for people living with obesity, highlighting the need for longer studies to assess long-term impacts.
  

Intermittent fasting gains further attention as a weight-loss approach

Intermittent fasting has become an increasingly popular method for managing weight, with growing evidence suggesting it may rival or even outperform traditional calorie-reduction diets in some respects. This dietary pattern restricts the window during which food is consumed each day, prompting the body to draw on fat reserves for energy once its immediate glucose supply is depleted.

Prominent institutions such as Johns Hopkins Medicine have long acknowledged the potential health benefits of intermittent fasting, which may extend beyond weight control to broader metabolic health.

Obesity’s continuing burden on public health

Obesity remains a critical public health challenge, affecting approximately two in five adults in the United States. It imposes an estimated annual cost of $173 billion on the American healthcare system. Carrying excess body weight is well established as a major risk factor for chronic diseases, including cardiovascular disease and type 2 diabetes.

Against this backdrop, researchers continue to explore diverse dietary strategies that might help reduce obesity prevalence and mitigate its health impacts.

Large-scale study identifies alternate-day fasting as particularly beneficial

In a recent high-quality analysis published in The BMJ, researchers from the Harvard T.H. Chan School of Public Health, working alongside colleagues from international institutions, sought to evaluate the effectiveness of different intermittent fasting methods. Their investigation pooled data from more than 6,500 adults enrolled in 99 clinical trials worldwide. Most participants were living with obesity and had additional health conditions.

Their findings pointed to alternate-day fasting — a regime where individuals eat normally one day and completely abstain from caloric intake the next — as the most effective intermittent fasting strategy compared to both standard calorie restriction and other time-restricted eating patterns.

As the Harvard team summarised:

“Among all intermittent fasting methods studied, alternate-day fasting – where a person eats normally one day and completely abstains from food the next – was shown to be the most effective.”

Measurable improvements in weight and cardiovascular risk factors

Participants who adopted alternate-day fasting achieved greater weight reduction, losing on average 2.8 pounds (approximately 1.3 kg) more than those adhering to traditional calorie-controlled diets. Beyond weight loss, this approach was linked with notable improvements in several key markers associated with cardiovascular disease and type 2 diabetes risk.

These included significant reductions in waist circumference, total cholesterol, low-density lipoprotein (LDL or “bad”) cholesterol, triglycerides, and C-reactive protein — a marker of systemic inflammation. Collectively, these changes suggest potential benefits for heart health and metabolic disease prevention.

Caution warranted: differences below clinical thresholds

Despite these encouraging outcomes, the researchers highlighted that the differences in weight loss did not meet the commonly accepted threshold of clinical significance, typically defined as a minimum of 4.4 pounds (2 kg) in individuals with obesity. This means that while alternate-day fasting demonstrated statistically meaningful results, the average benefits may not translate into substantial clinical improvements without further supportive evidence.

Zhila Semnani-Azad, who led the study, underscored the need for a cautious and personalised approach:

“Intermittent fasting, despite its promising results, may not be suitable for everyone. Before making significant dietary changes, it is essential to consult healthcare professionals and consider personal medical history, lifestyle, social circumstances, and potential for sustained adherence.”

Looking ahead: need for longer trials

The researchers called for extended studies to explore whether intermittent fasting — and alternate-day fasting in particular — can deliver lasting weight management and cardiovascular benefits over time. Such evidence would be crucial to inform clinical guidelines and support people living with obesity in choosing the most appropriate dietary strategies.

This new analysis offers valuable insights into how intermittent fasting might contribute to tackling obesity and its related health risks, while reinforcing the importance of individualised medical advice and long-term research.

CCH Insight:

There are undoubted benefits to be gained from intermittent fasting, including weight loss. However, the practicalities of some of these diets, such as alternate day fasting, may be very challenging for people living with obesity. Eating next to nothing one day and then normal meals the next can be difficult, especially for people who have cravings or experience ‘food noise’, for example. Time- restricted eating, where the same eating pattern is adhered to every day, may therefore be a more practical form of intermittent fasting for people with obesity, rather than alternate day fasting.

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Study shows training cuts weight bias and improves clinical practice in obesity care

Key Takeaways:

• A four-hour continuing medical education (CME) intervention significantly reduced healthcare professionals’ negative stereotypes towards people living with obesity, while increasing empathy and confidence – effects that persisted up to 12 months.
• The intervention led to tangible changes in clinical practice, including higher rates of obesity diagnosis and referrals to lifestyle programmes, obesity medicine, and bariatric surgery.
• Experts argue more such training is urgently needed, given widespread weight bias in healthcare and the chronic, complex nature of obesity.
  

Introduction: Confronting bias in healthcare

Many healthcare professionals (HCPs) hold negative attitudes towards people living with excess weight or obesity. This weight bias is not merely a social issue – it can significantly undermine patient care. Now, new research demonstrates that clinicians’ views and behaviours can be reshaped through targeted education.

In a study published in the Journal of General Internal Medicine, researchers led by Dr Amanda Velazquez of the Centre for Weight Management and Metabolic Health and the Jim and Eleanor Randall Department of Surgery at Cedars-Sinai Medical Center in Los Angeles found that a structured four-hour CME programme could meaningfully shift both attitudes and practice.

The educational intervention

In April 2021, a single-site symposium was held within the Kaiser Permanente Southern California healthcare system. It invited a broad cross-section of 472 eligible HCPs across specialties – from plastic surgeons and obstetricians to nurses and emergency medical technicians.

Dr Velazquez highlighted the rationale:

“There is a considerable gap in the education of healthcare professionals about obesity,” she told Medscape Medical News.
“Our study was unique in that it had a broad target group and invited professionals across all specialties… Our goal was to move the needle toward greater comfort in referring their patients to appropriate obesity management.”

She noted that many health conditions treated outside obesity medicine – including psoriasis, cardiometabolic disease and impaired fertility – are worsened by excess weight.

Measuring and shifting attitudes

Participants completed a 16-item questionnaire originally developed by Robert F. Kushner and colleagues to assess three aspects of weight bias:

• Negative stereotypes, such as “Individuals with obesity have themselves to blame”
• Empathy, such as recognising that “People with obesity feel stigmatized by the medical profession”
• Confidence, such as feeling comfortable discussing weight.
  

Immediately after the programme, results showed statistically significant improvements:

• Negative stereotypes dropped from 2.81 ± 0.47 to 2.50 ± 0.46 (P < .001).
• Empathy increased from 3.33 ± 0.64 to 3.47 ± 0.63 (P = .006).
• Confidence rose from 3.10 ± 0.86 to 3.85 ± 0.79 (P < .001).
  

These positive shifts persisted at both four- and twelve-month follow-up.

Tangible changes in clinical practice

Beyond self-reported attitudes, the researchers examined real-world clinical behaviour by comparing electronic medical record data for 218 participants and 89 non-participants over the following year.

After adjusting for factors such as years in practice, race/ethnicity, gender, profession type, practice type, and patient panel size, those who attended the CME were significantly more likely to:

• Diagnose obesity (OR, 1.60; 95% CI, 1.54–1.66),
• Refer to healthy lifestyle programmes (OR, 1.27; 95% CI, 1.19–1.36),
• Refer to obesity medicine specialists (OR, 1.87; 95% CI, 1.63–2.14),
• And, for patients with a BMI ≥ 35, refer for bariatric surgery (OR, 2.12; 95% CI, 1.70–2.67).
  

In contrast, the comparison group’s rates largely remained unchanged or decreased.

Dr Velazquez admitted she was not prepared for the scale of change.

“The increase in the number of referrals to obesity care was so overwhelming, we had to change the BMI eligibility criterion to handle the influx,” she explained.
With referrals to the obesity clinic doubling, they raised the threshold for new referrals from BMI ≥ 30 to BMI ≥ 35.

Broader expert views

Leslie Heinberg, PhD, professor of medicine and vice chair for psychology at the Cleveland Clinic, praised the work:

“It’s an interesting and comprehensive study that goes beyond previous work in attitudinal change to look at change in actual practice behaviour around obesity.”

While she was unsurprised by the immediate shift in attitudes – noting, “We all know the right answers to give” – she found it notable that the change persisted.

“In my practice, patients often report experiencing weight stigma during interaction with their HCPs. But healthcare should be sensitive to patients across the entire weight spectrum.”

Heinberg added that most HCPs receive little or no training on obesity.

“They might get one lecture during training, but 40% of the patients they treat will have obesity.”
At her institution, all new clinical staff undergo onboarding in obesity bias, with annual refreshers.

Dr Carolynn Francavilla, an obesity medicine specialist in Colorado, also applauded the findings.

“As someone who dedicates a significant amount of my time to developing CME and educating clinicians, I find it very encouraging that this study was able to demonstrate both reduced weight bias and improved referrals for care,” she told Medscape Medical News.
“While most physicians are now aware of treatment options, many do not understand the chronic nature of the disease and many still believe that willpower is enough to treat obesity.”

Next steps for research and practice

The authors concluded that carefully designed CME can reduce HCPs’ weight bias and encourage better use of the full spectrum of obesity treatments.

“We’re hoping to apply the intervention in other groups to see if it has the same positive impact on practice,” said Dr Velazquez.
However, she noted that since the original study was run before the rise of GLP-1 therapies, future programmes will need updating.

The researchers called for additional trials to explore long-term changes beyond one year and to incorporate pharmacotherapy into the educational content.

Funding and disclosures

This work was funded by the Southern California Permanente Medical Group, with open access support from the Statewide California Electronic Library Consortium.

Dr Velazquez serves on advisory boards for WW, Eli Lilly, and Intellihealth and consults for Novo Nordisk. Coauthor A. Janet Tomiyama’s work was supported by the NIH and NSF. Dr Kushner consults for Altimmune, Pfizer, Eli Lilly and serves on advisory boards for Novo Nordisk and WW. Joseph Nadglowski is employed by the Obesity Action Coalition. Dr Francavilla is a speaker and adviser for Eli Lilly and holds personal investments in Eli Lilly and Novo Nordisk. Dr Heinberg declared no relevant conflicts.

CCH Insight:

This is an impressive study, which shows what impact even a short training course in obesity care can achieve. Around the globe there is a general lack of training of health professionals in obesity care, and the lack of understanding of obesity as a complex, chronic condition manifests as not just a lack of confidence and self-efficacy to treat obesity, but also a continuation of long-held stereotypes and stigmatisation of people living with obesity. High quality obesity care training for health professionals is essential if we are to improve access to care and outcomes for people with obesity.

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Greater fruit intake linked to lower abdominal fat in US children, study finds

Key Takeaways: 

• A nationally representative study of over 1,700 children in the United States found that higher fruit consumption is significantly associated with lower levels of abdominal adiposity.
• Children who consumed moderate to high amounts of fruit had smaller waist circumferences and reduced abdominal height, especially among boys and those with healthier lifestyle habits.
• The findings suggest fruit’s low energy density and high fibre content may be key contributors to improved weight outcomes, although causality cannot be established due to the study’s cross-sectional design.
  

Introduction

A new study led by Professor Larry A. Tucker of Brigham Young University, published in Frontiers in Nutrition, has identified a significant association between fruit intake and abdominal adiposity among children in the United States. The research highlights the potential role of fruit consumption in addressing paediatric obesity, particularly abdominal fat accumulation, which is a known risk factor for numerous metabolic diseases.

Context: The Obesity Crisis in Children

Childhood overweight and obesity remain a pressing public health concern in the United States, currently affecting over 40% of children. The prevalence of these conditions has increased nearly fivefold in the past half-century among children and adolescents.

Excess body weight during childhood increases the risk of a wide range of physical and psychological health problems, including:

• Insulin resistance and type 2 diabetes
• High blood pressure and cholesterol levels
• Cardiovascular disease
• Depression and anxiety

Although Body Mass Index (BMI) is commonly used to assess weight status, it does not distinguish between fat and lean mass, nor does it indicate where fat is distributed. This is a critical limitation, as abdominal adiposity – excess fat around the midsection – has been shown to be more predictive of cardiometabolic risk than BMI alone.

According to the Lancet Diabetes & Endocrinology Commission, waist circumference and other measures of central adiposity should be prioritised in research and clinical assessments. The accumulation of abdominal fat is especially influenced by dietary patterns, including the consumption of high-energy-dense foods, which are typically high in fat and low in water and fibre.

Why Fruit Matters

Fruits are among the lowest energy-dense food groups, thanks to their high water and fibre content and minimal fat. Numerous studies have indicated that diets rich in fruits and other low-energy-dense foods are effective in supporting healthy body weight.

Given these properties, this study sought to examine whether there is a measurable association between fruit intake and abdominal fat among a nationally representative sample of children aged 8 to 11 years in the United States.

Study Design and Methodology

The research analysed data from 1,707 children enrolled in the National Health and Nutrition Examination Survey (NHANES), a population-based study conducted by the US National Center for Health Statistics (NCHS) and the Centers for Disease Control and Prevention (CDC).

Key measurements and parameters included:

• Fruit intake: Assessed using two 24-hour dietary recall interviews. Fruit juices were excluded. Intake was calculated as the percentage of total daily energy derived from fruit.
• Abdominal adiposity: Measured using waist circumference and sagittal abdominal diameter (also known as abdominal height).
• Confounding variables: Adjusted for age, sex, race, household size, survey year, physical activity, recreational computer use, total energy intake, and consumption of macronutrients (carbohydrates, protein, fat), sugar, saturated fat, and fibre.

Results and Observations

Fruit Consumption Patterns

• 27% of children reported consuming no fruit at all.
• 36% consumed a low amount of fruit.
• 37% consumed a moderate-to-high amount of fruit.
• On average, fruit made up 10% of total energy intake.

Association with Abdominal Fat

After accounting for confounding factors, the study found that:

• Children who consumed more fruit had significantly smaller waist circumferences and lower sagittal abdominal diameters.
• The association was stronger and statistically significant for sagittal abdominal diameter.
• For waist circumference, the association was marginally significant in the fully adjusted model.
  

Lifestyle Factors Matter

Subgroup analyses revealed that the benefits of fruit intake were more pronounced among children who:

• Engaged in at least one hour of physical activity on four or more days per week.
• Spent two hours or less per day on recreational computer use.
  

Among children who were less active or had higher screen time (three hours or more per day), the association between fruit intake and abdominal adiposity was not significant.

Nutritional Insights

Children with higher fruit intake were found to consume:

• Greater amounts of dietary fibre, natural sugars, and carbohydrates.
• Lower levels of saturated fat.
  

These dietary patterns are consistent with the properties of fruit as a low-energy-dense food. Fibre, in particular, may help explain the association with lower abdominal fat, as it contributes to satiety, regulates gut microbiota, and has been shown to support metabolic health.

Fruits are also rich in micronutrients and bioactive compounds, including:

• Vitamins
• Antioxidants
• Flavonoids
• Phytochemicals

These compounds are known to reduce inflammation, improve insulin sensitivity, and regulate hunger-related hormones such as leptin and ghrelin – all of which may support healthy weight management.

Public Health Implications

Despite the benefits highlighted in this study, approximately 80% of the US population fails to meet the recommended daily fruit intake outlined in the 2020–2025 Dietary Guidelines for Americans. Professor Tucker commented:

“Fruit intake is widely underconsumed in the United States. These findings support the view that fruit can play a crucial role in the prevention of abdominal obesity in children.”

He urged healthcare professionals, parents, and educators to encourage fruit consumption as part of broader efforts to combat paediatric obesity and its associated health complications.

Limitations and Future Research

While the study presents compelling evidence of an association between fruit intake and reduced abdominal fat, its cross-sectional design limits the ability to establish causality. Longitudinal or experimental studies would be necessary to confirm whether increasing fruit consumption directly leads to reduced abdominal adiposity.

Additionally, the NHANES methodology involves oversampling certain ethnic groups, such as Mexican Americans, which may have influenced the racial distribution of the study population.

Conclusion

This study contributes to a growing body of evidence suggesting that fruit consumption supports healthier body composition in children. With paediatric obesity continuing to rise, particularly in the United States, promoting higher fruit intake may offer a simple, evidence-informed strategy for reducing central fat accumulation and associated health risks in young people.

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Global study provides practical guidance on antibiotic dosing for people with obesity

Key Takeaways: 

• A major systematic review has revealed how obesity alters the distribution and efficacy of antibiotics, with significant implications for dosing and therapeutic outcomes.
• While certain antibiotics such as β-lactams may not require routine adjustments, classes like aminoglycosides and glycopeptides require close monitoring and individualised dosing.
• The research team calls for global data sharing and improved pharmacokinetic studies to inform evidence-based dosing guidelines.
  

Introduction: A Call for Precision in Dosing

A large international team of researchers has published the most comprehensive analysis to date on antibiotic dosing in people living with obesity. Led by Dr Anne-Grete Märtson of Leiden University and Dr Thomas Tängdén of Uppsala University, the review brings together findings from 128 studies and proposes practical recommendations for clinical dosing adjustments. The work, published in The Lancet Infectious Diseases on 15 May, represents a significant step towards individualised antibiotic therapy in a population often overlooked in clinical pharmacology.

“It’s high time researchers started sharing more data,” said Märtson, underscoring the pressing need for greater collaboration to close longstanding gaps in clinical guidance.

Clinical Foundations and Rising Challenges

Märtson’s interest in the topic was informed by her early career as a clinical pharmacist in Estonia, where she participated in hospital ward rounds and focused on drug safety and dosing. “As a clinical pharmacist, I focused on the medication: was a certain combination of drugs safe, what was the optimal dose?”

Today, with rising obesity rates globally, clinicians are increasingly encountering challenges in treating infections effectively. “We’re increasingly seeing limited responses to administered medicines – in some patients the infection even worsens,” she noted. Complicating matters, most drug labels do not include dosing guidance for people with obesity, leaving clinicians without clear direction.

How Obesity Affects Antibiotic Pharmacokinetics

The review explains that obesity can significantly influence how antibiotics are absorbed, distributed, and cleared from the body. Changes in body composition, such as increased fat and muscle mass, and potential organ dysfunction, especially of the liver or kidneys, can affect the volume of distribution and drug metabolism.

“Substantial changes can occur in the volume of distribution due to increased fat and muscle mass, and tissue drug concentrations might be lowered,” the authors write.

Mahyar Etminan, a drug safety epidemiologist with EpiLytics Consulting who was not involved in the study, commented that “you need more of the drug to get into the tissue and that usually means higher doses than what we usually use in non-obese patients.” He also advised choosing antibiotics with higher tissue penetration.

128 Studies Analysed Across Multiple Drug Classes

Märtson and her colleagues systematically reviewed over 6,000 studies, narrowing their analysis to 128 that met strict inclusion criteria. Of these, 57 focused on β-lactam antibiotics, while 45 examined glycopeptides, lipoglycopeptides, and oxazolidinones. The analysis covered individuals aged 18 years and older with a Body Mass Index (BMI) over 30.

The findings showed that commonly prescribed antibiotics for pneumonia, urinary tract infections, and other bacterial conditions behave differently in people with obesity. “They distribute differently across the body’s tissues. Sometimes too little reaches the lungs, even though you’re trying to treat a lung infection,” Märtson explained.

Recommendations by Antibiotic Class

The review provides tailored guidance for specific classes of antibiotics:

β-lactams

This broad class, which includes penicillins and cephalosporins, is widely used for acute infections. Although obesity modestly alters their pharmacokinetics, the review concludes:

“Obesity modestly alters the pharmacokinetics of β-lactam antibiotics, but evidence does not support routine dose adjustments.”

However, it cautions against overly aggressive dosing due to the risk of toxic concentrations and side effects.

Aminoglycosides and Glycopeptides

These antibiotics are used for severe infections and require careful dose management.

“Therapeutic drug monitoring and the monitoring of creatinine clearance are highly recommended to guide maintenance dosing,” the authors state.

For aminoglycosides in particular, standard practice already includes therapeutic drug monitoring due to risks of nephrotoxicity and irreversible hearing damage. Dosing based on adjusted body weight is recommended to avoid under- or overdosing.

Other Antibiotic Classes

The study found that not all antibiotics require specific adjustments. In some cases, the pharmacological properties of the drug mean standard doses may remain appropriate, though further studies are needed to confirm this across more antibiotic types.

Optimising Dosing in Critical Care Settings

Märtson highlighted practical clinical strategies such as modifying infusion duration. “In critically ill patients, it can be helpful to administer the dose over two to four hours instead of half an hour via infusion,” she noted, emphasising the need to maintain appropriate plasma concentrations for effective treatment.

Gaps in the Data and the Need for Shared Research

Despite these insights, the researchers emphasise that much of the existing evidence remains limited. Many included studies were small-scale, and more robust pharmacokinetic data are needed. “There are excellent methods available to conduct high-quality research into this issue,” said Märtson, referencing tools like CT imaging to assess body composition and predictive modelling using large datasets.

The authors stress that:

“In the absence of robust pharmacokinetic data to inform dose adjustments, therapeutic drug monitoring can be useful to guide individualised dosing.”

They also call on future research to account for variables such as infection site, severity of illness, pathogen susceptibility, and potential drug toxicity when considering dosage in people with obesity.

Conclusion: Towards Evidence-Based Personalised Antibiotic Dosing

Märtson, Tängdén, and their multinational team – including contributors from the United States, Belgium, Austria, Germany, and Australia – have laid a critical foundation for improving antibiotic treatment in people with obesity. Their systematic review offers both immediate clinical value and a roadmap for future research.

As Märtson concluded, “I hope researchers will start sharing more data, so we can ultimately establish proper guidelines for all antibiotics.”

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Low-calorie diets linked to increased risk of depression, especially in men and people living with obesity

Key Takeaways: 

• Low-calorie diets may increase the risk of depressive symptoms, particularly among men and people living with overweight or obesity, according to a large population study.
• Nutritional deficiencies linked to unsupervised calorie restriction may negatively affect mental wellbeing, highlighting the importance of dietary quality.
• The findings challenge previous clinical studies suggesting mood benefits from calorie restriction, calling attention to the gap between controlled interventions and real-world dieting behaviour.
  

Introduction

Restrictive dieting is a common approach to weight management, but emerging evidence suggests that cutting calories—especially without professional guidance—may have unintended consequences for mental health. A new Canadian study published in BMJ Nutrition, Prevention & Health has found a link between low-calorie diets and an increased risk of depressive symptoms, particularly among men and individuals living with overweight or obesity.

Study Overview

Researchers analysed data from 28,525 adults who took part in the US National Health and Nutrition Examination Survey (NHANES). Participants completed a standardised mental health questionnaire, which assessed symptoms such as persistent low mood, fatigue, and disturbed sleep.

The study revealed that individuals who were actively restricting their calorie intake scored higher for depressive symptoms than those who were not dieting. The association was especially pronounced among:

• Men
• People classified as having overweight or obesity

Overall, around 8% of participants reported symptoms of depression, while over 70% were living with overweight or obesity—a demographic more likely to engage in calorie-restrictive dieting.

The Role of Nutritional Deficiency

While the study could not prove causation, the researchers proposed that self-imposed dietary restrictions may lead to insufficient intake of essential nutrients—particularly protein, vitamins, and minerals. Such deficiencies can place the body under physiological stress, potentially exacerbating or triggering symptoms of poor mental health.

This stands in contrast to earlier clinical trials where calorie-restricted diets appeared to improve mood. However, the authors of the current study point out that these prior interventions were typically nutritionally balanced and closely monitored, unlike the unsupervised and potentially imbalanced dieting patterns seen in the general population.

Diet Quality Matters

The study draws a distinction between restrictive dieting and overall dietary quality. Diets that are rich in whole foods—including fruits, vegetables, whole grains, nuts, and lean protein—have consistently been associated with lower rates of depression. In contrast, those high in ultra-processed foods and refined carbohydrates are linked to higher depression risk.

Expert Commentary

Professor Sumantra Ray, Executive Director of the NNEdPro Global Institute for Food, Nutrition and Health, underscored the wider implications of the findings:

“This adds to the growing body of evidence linking diet and mental health.

Restrictive diets low in nutrients important for cognitive function, such as omega-3 and vitamin B12, may contribute to depressive symptoms. However, further well-designed studies are needed to better understand these relationships.”

Implications for Healthcare Practice

While the study is observational and cannot confirm a causal relationship, it offers a timely reminder for healthcare professionals. When supporting individuals who wish to lose weight, especially those with existing vulnerabilities to depression or anxiety, it is crucial to:

• Emphasise nutritional adequacy, not just calorie reduction
• Support patients in choosing sustainable, balanced dietary patterns
• Consider mental health screening as part of weight management strategies

In summary, the findings call for a more nuanced approach to dietary advice—one that respects the complex interplay between physical and mental health, and avoids simplistic calorie-cutting recommendations that may do more harm than good.

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Shedding excess weight in midlife may protect against chronic illness and early death, study finds

Key Takeaways:

• Adults who reduced their weight from overweight to a healthy range in midlife—without medication or surgery—experienced significantly lower risks of chronic disease and death.
• These health benefits extended beyond the reduced risk of type 2 diabetes and were evident even decades later.
• Sustained, intentional weight loss through lifestyle changes may offer long-term protective effects, especially when initiated between the ages of 40 and 50.

Introduction

A new study published in JAMA Network Open has provided compelling evidence that sustained weight loss during midlife can significantly reduce the long-term risk of chronic illness and premature death. While pharmacological treatments such as GLP-1 receptor agonists and bariatric surgery are effective in promoting weight loss, they carry inherent risks. This research focuses on the long-term outcomes of weight loss achieved without these medical or surgical interventions.

Obesity is a well-established risk factor for several chronic conditions, particularly type 2 diabetes. However, the long-term health outcomes associated with lifestyle-induced weight loss—outside of diabetes risk—remain less well understood. This study aimed to clarify these outcomes by examining the health trajectories of individuals aged 40 to 50 who achieved and maintained weight loss over multiple decades.

Study Overview

The analysis drew upon data from 23,149 adults enrolled in three long-running cohort studies:

• Whitehall II Study (WHII) (1985–1988, United Kingdom)
• Helsinki Businessmen Study (HBS) (1964–1973, Finland)
• Finnish Public Sector Study (FPS) (2000, Finland)

Participants’ body mass index (BMI) was measured repeatedly over periods ranging from 12 to 35 years. Individuals were then categorised into four groups based on their BMI trajectories:

1. Persistent healthy weight (BMI consistently <25)
2. Weight loss (BMI reduced from ≥25 to <25)
3. Weight gain (BMI increased from <25 to ≥25)
4. Persistent overweight (BMI consistently ≥25)

The study excluded individuals who used medications or underwent surgery for weight loss, focusing solely on lifestyle-driven changes. Furthermore, participants were initially free from diagnosed chronic disease, limiting the likelihood of confounding due to weight loss caused by illness.

Key Findings

Risk of Chronic Disease

Participants who moved from an overweight to a healthy weight category and sustained this reduction experienced significantly lower risks of chronic disease. Notably:

• In the WHII cohort, individuals who lost weight or maintained a healthy BMI were 50% less likely to develop one or more chronic conditions over a median follow-up of 23 years, compared to those who remained overweight.
• After adjusting for the effects of reduced type 2 diabetes risk, the chronic disease risk remained 40% lower, suggesting additional health benefits.
• In the FPS cohort, weight loss was associated with a 60% reduction in chronic disease risk over a 12-year median follow-up.

These reductions were accompanied by healthier clinical profiles, such as lower mean blood pressure and total cholesterol levels among those who lost weight.

Mortality Risk

In the HBS cohort, participants who achieved a healthy weight had a 20% lower risk of death over 35 years. The median age at death in this cohort was 91, highlighting the extended timeline over which benefits may be realised.

Weight Gain and Health Risk

Individuals who moved from a healthy BMI into the overweight category had a higher risk of developing chronic disease than those who maintained a healthy weight. However, their risk was still lower than those who were persistently overweight.

Methodological Strengths and Considerations

A key strength of this study is its ability to exclude confounding by unintentional weight loss—a marker often associated with disease, frailty, or undiagnosed cancer—by selecting relatively young, healthy participants. This helps to isolate the effects of deliberate, lifestyle-induced weight loss.

The findings also contrast with previous studies that assessed weight loss through medication or surgery. While such treatments result in more dramatic weight changes, the long-term benefits—especially on cardiovascular health or mortality—have remained inconsistent. This may partly reflect the concurrent use of medications such as statins in control groups or short follow-up periods.

Importantly, the study did not specifically verify whether the observed weight loss was intentional. However, the researchers argued that, given the health status and age of the participants, it was reasonable to assume the changes were deliberate and achieved through modifications in diet, physical activity, or other lifestyle factors.

The FPS cohort relied on self-reported weight and height, which introduces a potential for reporting bias. In contrast, the WHII and HBS cohorts used measured BMI values, lending stronger credibility to their findings.

Implications for Practice and Public Health

This study provides robust evidence that moderate, sustained weight loss during midlife can have enduring health benefits, even when achieved without pharmacological support. Importantly, these benefits extend beyond the well-documented reductions in type 2 diabetes risk to include decreased risks of other chronic diseases and premature mortality.

Furthermore, the results reinforce the value of early intervention. Reducing weight in one’s 40s or early 50s appears to change the trajectory of long-term health outcomes, with positive effects that may take decades to fully manifest.

The findings also highlight a public health challenge: while people living with severe obesity may require pharmacotherapy or surgery, many individuals with moderate overweight status may significantly benefit from supported lifestyle changes. These results suggest that weight management efforts should be actively promoted and supported at midlife to yield maximum long-term impact.

Conclusion

The study found that individuals who transitioned from an overweight BMI to a healthy range during midlife—without the aid of weight loss medications or surgery—experienced a significantly lower risk of chronic disease and, in some cases, reduced all-cause mortality. These findings underscore the potential of midlife lifestyle changes to yield meaningful and sustained health benefits well into older age.

As the global burden of overweight and obesity continues to rise, these insights serve as a call to action for healthcare providers and public health authorities to support early, intentional weight management through non-pharmacological means whenever possible.

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Maternal obesity linked to increased risk of infection-related hospital admissions in children, study finds

Key Takeaways:

• Children born to people with obesity (BMI ≥35) face a significantly increased risk of hospital admission for infections up to age 15.
• The risk is most pronounced during infancy and again between ages 5 and 15, with respiratory, gastrointestinal, and viral infections driving most admissions.
• Caesarean delivery and child obesity in early years appear to partly explain the association, suggesting potential areas for public health intervention.

Introduction

A long-term UK study published in BMJ Medicine has found that children born to women with obesity—specifically those with a body mass index (BMI) of 35 or above—are at an elevated risk of hospitalisation due to infections. The study, based on nearly 10,000 births in Bradford, England, highlights how maternal health before and during pregnancy can have long-lasting implications for child health, particularly regarding immune-related outcomes.

Global and Biological Context

Researchers emphasise that maternal obesity is a growing global health issue, with estimates suggesting it could affect nearly 1 in 4 pregnancies worldwide by 2030. Obesity is marked by chronic low-grade inflammation, which is associated with a range of biological changes—disruption of immune function, alterations in gene expression, and changes to the gut microbiome—all of which may influence foetal development and subsequent childhood health.

While past studies have investigated the potential link between maternal obesity and childhood infections, findings have been inconsistent. Furthermore, it has remained unclear whether modifiable factors such as breastfeeding, method of delivery, and pregnancy-related weight gain might influence this relationship.

Study Design and Population

To explore these questions, researchers analysed data from the Born in Bradford study, a prospective birth cohort that investigates how social, environmental, and genetic factors affect maternal and child health over time.

The analysis included 9,037 women who gave birth to a live infant at Bradford Royal Infirmary between March 2007 and December 2010 and for whom both height and weight data were available. Of these participants:

• 45% were of Pakistani origin,
• 40% were white British, and
• 37% lived in the most socioeconomically deprived areas of the UK.

In total, 9,540 children were followed for health outcomes—specifically hospital admissions for infections—from birth until October 2022, or until the child either withdrew from the study, died, or turned 15.

Maternal BMI and Measurement

Maternal BMI was assessed at multiple time points:

• At the first antenatal (booking) appointment,
• Again between 26 and 28 weeks’ gestation, and
• During a routine third-trimester appointment.

Approximately 30% of the women were classified as overweight, and 26% were living with obesity—10% of whom had obesity grades 2 or 3 (BMI ≥35) in the first trimester.

Infection Categories and Hospital Admissions

Childhood infections were classified into several categories:

• Upper respiratory tract,
• Lower respiratory tract,
• Skin and soft tissue,
• Genitourinary,
• Gastrointestinal,
• Invasive bacterial, and
• Multisystem viral infections.

Over the follow-up period, 5,009 infection-related hospital admissions were recorded. Around 30% of the children were hospitalised for an infection at least once:

• 19% had one admission,
• 6% had two,
• 4% had three or more.

Admission rates were highest during infancy—134.6 admissions per 1,000 person-years—which declined to 19.9 per 1,000 person-years in children aged 5 to 15.

Maternal BMI and Infection Risk

There was a clear gradient in infection risk according to maternal BMI:

• Children of mothers with a healthy BMI had an admission rate of 39.7 per 1,000 person-years.
• This increased to 60.7 per 1,000 person-years among children whose mothers had obesity grades 2-3.

After adjusting for potential confounders (maternal age, ethnicity, and area deprivation), the risk remained significantly higher in children born to people with obesity grades 2-3:

• These children were 41% more likely to be admitted for an infection under age 1.
• They were 53% more likely to be admitted between ages 5 and 15.

The association appeared stronger in boys than girls and among children of Pakistani mothers compared to those of white British mothers. Respiratory, gastrointestinal, and viral infections accounted for the majority of excess hospital admissions.

Modifiable Risk Factors

The researchers explored whether certain modifiable factors might influence this association:

• Preterm birth accounted for 7% of the link between maternal obesity and infection risk.
• Caesarean section delivery accounted for 21%.
• Child obesity at ages 4–5 contributed to 26%.

Interestingly, breastfeeding for six or more weeks and excessive pregnancy weight gain (both average weekly and total) were not significantly associated with infection risk in this study.

Limitations and Interpretation

As an observational study, the findings cannot establish causality. Several limitations were noted:

• Data came from a single hospital in Bradford, limiting generalisability.
• Missing data for breastfeeding duration and child BMI weakened the completeness of some analyses.
• Environmental and lifestyle factors—such as household crowding or exposure to smoking—were not included.

Despite these limitations, the authors argue that the findings underscore a broader public health concern. They write:

“The findings of our study highlight the need for public health campaigns and additional support for healthcare professionals to help women of reproductive age achieve and maintain a healthy body weight.

“Although the results indicated a modest effect of maternal obesity, and only in those with obesity grades 2–3, the potential effect on a large number of children globally is substantial.”

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Collagen-based protein bars may support weight loss, study suggests

Key Takeaways:

• A 12-week study found that adults with overweight or class 1 obesity who consumed 20g of collagen daily experienced greater weight loss and improved cardiometabolic health compared to a control group.
• The collagen group also reported increased satiety and reduced hunger throughout the study period, without significant loss of fat-free mass.
• While the findings are encouraging, experts caution that collagen is not a substitute for a structured weight management programme and lifestyle change.
  

Background: Obesity Rates and Cost Barriers to Treatment

With over 70% of adults in the United States classified as having overweight or obesity, the demand for effective and affordable weight loss strategies continues to rise. Although medications such as GLP-1 receptor agonists are gaining popularity, their high cost renders them inaccessible for many individuals.

In this context, a recent study published in Nutrients explores whether a more affordable and widely available supplement—collagen—could offer a modest but meaningful aid to weight management.

Study Overview: Collagen Supplementation and Dietary Guidance

Researchers recruited 64 adult participants, all with body mass index (BMI) measurements ranging from overweight to class 1 obesity. All participants were advised to follow a balanced diet modelled on the Mediterranean approach, rich in fruits, vegetables, whole grains, healthy fats, fish, and poultry.

The participants were then randomly assigned to one of two groups:

• Intervention group: 32 individuals consumed two protein bars daily (each containing 10g of bovine-derived collagen and 90 calories).
• Control group: 32 individuals adhered to the dietary recommendations without receiving a protein bar or placebo.

Both groups consumed a similar baseline diet, with the intervention group ingesting slightly more calories due to the added protein bars. Throughout the 12-week period, participants attended regular assessment appointments to collect data on weight, blood pressure, blood biomarkers, urine and faecal samples, and self-reported food intake and appetite levels.

Findings: Greater Weight Loss and Metabolic Improvements in Collagen Group

At the end of the study, the group receiving collagen protein bars demonstrated superior outcomes across several health metrics:

• Average weight loss: 6.6 pounds (≈3kg) in the collagen group compared to 3.3 pounds (≈1.5kg) in the control group.
• Systolic blood pressure: Decreased by an average of 8 mm Hg in the collagen group, while it slightly increased (0.4 mm Hg) in the control group.
• Waist circumference, BMI, and fatty liver index: All improved more significantly in the collagen group.

Importantly, the intervention group retained or improved fat-free mass, indicating preservation of muscle tissue during weight loss—a common concern with calorie reduction strategies.

Participants consuming collagen bars also consistently reported increased satiety and reduced hunger, with these effects sustained across monthly assessments at weeks 4, 8, and 12.

Expert Commentary: Encouraging but Not Conclusive

Despite the promising outcomes, some experts advise caution when interpreting the results.

Dr Mir Ali, a board-certified general and bariatric surgeon and medical director at MemorialCare Surgical Weight Loss Center, told Medical News Today:

“This was a good study that showed the potential benefits of protein bars with collagen. I am not certain that the effects can all be attributed to collagen as protein meal replacements are also beneficial to weight loss.”

Dr Ali emphasised that while collagen appears safe for most people, some may experience minor side effects:

“I am not aware of any major concern with collagen supplements; perhaps a bloating sensation as collagen swells when ingested. Patients with poor gastric motility may feel more bloating, but overall collagen appears safe.”

Strengths and Limitations of the Study

Dr Hector Perez, lead bariatric surgeon at Renew Bariatrics, also commented on the study, calling it:

“A promising and well-structured pilot study.”

He cited the use of validated measures such as DEXA scans, and the focus on both subjective (appetite) and objective (metabolic) outcomes as methodological strengths. However, he also raised a note of caution:

“There’s a theoretical concern about kidney strain in people with impaired renal function if high protein supplements are overused, though this study’s dosage (20g/day) is moderate.”

A key limitation of the study is the potential conflict of interest: some authors are affiliated with the company that manufactures the collagen bars used in the trial.

Conclusion: Collagen as a Complement, Not a Cure

Both Ali and Perez agree that while collagen supplementation may support weight loss, it is not a panacea. Dr Perez summarised:

“I’d recommend collagen as a complement to a structured weight loss programme, not as a stand-alone solution. I always stress that no supplement replaces portion control, physical activity, and sustainable dietary habits.”

For individuals looking for accessible tools to support their weight loss journey, collagen supplements—particularly in protein bar form—may offer an affordable adjunct. However, they should be integrated into a broader, evidence-based approach to long-term weight management.

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Diet-induced obesity linked to anxiety and cognitive impairment in mice

Key Takeaways:

• Obesity in mice was linked to increased anxiety-like behaviours, altered brain signalling, and gut microbiome changes, suggesting a complex interaction between diet, brain function, and gut health.
• Findings reinforce the growing evidence of a gut–brain axis in mental health, highlighting that obesity may contribute directly to cognitive and emotional challenges.
• While conducted in mice, the study supports the value of multi-system approaches to obesity research, prevention, and intervention, particularly during adolescence.

Introduction: Rising Rates, Unanswered Questions

As obesity and anxiety both continue to rise—especially among younger populations—researchers are increasingly investigating whether these conditions are biologically connected. A new preclinical study led by Dr Desiree Wanders, Associate Professor and Chair of Nutrition at Georgia State University, suggests a potential causal link, identifying diet-induced obesity in mice as a driver of anxiety-like behaviours, disrupted brain function, and gut microbiome imbalances.

The findings will be presented at NUTRITION 2025, the annual flagship meeting of the American Society for Nutrition, held from 31 May to 3 June in Orlando, Florida.

Study Design: A Closer Look at the Brain–Gut–Diet Connection

To explore the neurocognitive impact of obesity, researchers developed a mouse model designed to mirror human obesity-related health outcomes. The study involved 32 male mice, observed from six to 21 weeks of age—equivalent to adolescence through early adulthood in humans.

During this time:

• Half of the mice were fed a low-fat diet, while
• The other half received a high-fat diet known to induce obesity.

By the end of the study period, the high-fat group exhibited:

• Significantly greater body weight, and
• Higher levels of body fat than their low-fat-fed counterparts.

Behavioural and Neurological Outcomes

Behavioural tests revealed that mice with obesity displayed more anxiety-like behaviours. Notably, they exhibited increased “freezing” responses—a defensive behaviour in rodents when perceiving threats. This behavioural profile was not seen in the lean control group.

Neurological analysis revealed changes in signalling within the hypothalamus, a brain region that plays a central role in:

• Regulating metabolism,
• Hormonal control, and
• Emotional behaviour.

Such alterations may help explain the cognitive impairments often reported in people living with obesity.

“Several studies have pointed to a link between obesity and anxiety, though it is still unclear whether obesity directly causes anxiety or if the association is influenced by societal pressures. Our findings suggest that obesity can lead to anxiety-like behaviour, possibly due to changes in both brain function and gut health.”
— Desiree Wanders, PhD

Microbiome Findings: Distinct Gut Profiles in Mice with Obesity

Beyond brain signalling, the study also explored the gut microbiota—microorganisms that reside in the gastrointestinal tract and are known to influence both digestion and brain health. In mice with obesity, the researchers observed marked differences in gut microbial composition compared to the lean group.

This supports a growing body of research into the gut–brain axis, suggesting that:

• The microbiome may regulate not only digestion but also emotional and cognitive function.
• Obesity-related changes in gut bacteria may be part of a chain reaction affecting brain health.

Implications for Public and Personal Health

Although animal models cannot replicate the full complexity of human biology and environment, Wanders emphasised the relevance of these results for human health strategies.

“These findings could have important implications for both public health and personal decisions. The study highlights the potential impact of obesity on mental health, particularly in terms of anxiety.”
— Desiree Wanders, PhD

The research adds weight to the argument that obesity’s consequences extend beyond metabolic disease and cardiovascular risk, reinforcing the importance of:

• Preventive strategies, particularly in childhood and adolescence;
• Early interventions, and
• Comprehensive health policies that address mental as well as physical health.

Contextual Considerations and Future Research

Wanders also cautioned against overly simplistic interpretations of the data:

“While our findings suggest that diet plays a significant role in both physical and mental health, it is important to remember that diet is just one piece of the puzzle,” she said. “Environmental factors, genetics, lifestyle choices and socioeconomic status also contribute to the risk of obesity and its associated health outcomes.”

Looking ahead, Wanders and her team plan to:

• Investigate the mechanisms through which diet-induced obesity alters the brain,
• Conduct parallel studies including female mice and different age groups, and
• Explore whether weight loss interventions might reverse or mitigate the observed changes in behaviour, brain function, and gut health.

Presentation Details

Dr Wanders will present the full research findings during the Obesity session at the Orange County Convention Center on Sunday, 1 June, from 11:45 a.m. to 12:45 p.m. EDT.

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Black tea kombucha reduces gut bacteria associated with obesity

Key Takeaways:

• Kombucha altered gut microbial composition, particularly in participants living with obesity, by increasing beneficial bacteria and reducing obesity-linked genera.
• Despite these microbial changes, no significant shifts were observed in short-chain fatty acid levels or markers of intestinal permeability.
• Black tea kombucha is rich in phenolic compounds, notably flavonoids, which may contribute to its potential anti-obesity effects.

Introduction

Obesity remains a mounting global health challenge, currently affecting over one billion people worldwide. This complex condition arises from the interplay of genetic, environmental, physiological, and behavioural factors, though the underlying mechanisms are still incompletely understood. Recent research has increasingly focused on the gut microbiota as a potential contributor to obesity and metabolic dysregulation. Dysbiosis—a disruption in the balance and diversity of gut microbes—has been implicated in the development and progression of obesity.

Diet plays a critical role in shaping the gut microbiome. One food item that has garnered significant attention for its potential microbiota-modulating effects is kombucha—a fermented tea produced using a Symbiotic Culture of Bacteria and Yeast (SCOBY). While numerous animal studies have suggested that kombucha, especially when derived from black tea, can beneficially influence the gut microbiome, evidence from human studies remains scarce.

This study, recently published in The Journal of Nutrition, aimed to address this gap by evaluating the effects of daily black tea kombucha consumption over an eight-week period on gut microbiota composition and intestinal health, in adults with and without obesity.

Study Design and Methods

Participant Selection

Out of 193 online respondents, 62 individuals were screened, and 46 met the eligibility criteria. Participants were divided into two groups based on body mass index (BMI):

• Group with normal-weight: Mean BMI of 21.64 kg/m²
• Group with obesity: Mean BMI of 34.47 kg/m²

Inclusion criteria required participants to be between 18 and 45 years old, have a BMI ≥18.5 kg/m², and be free from chronic diseases aside from obesity. Individuals were excluded for a range of reasons including recent antibiotic use, consumption of kombucha in the past month, vitamin supplementation, chronic medication use affecting lipid or glucose metabolism, unstable body weight, or being pregnant, lactating, or smokers.

Intervention and Data Collection

Participants consumed 200 mL of laboratory-prepared black tea kombucha daily for eight weeks. The kombucha was acidic (low pH) with a mildly sweet taste, achieved by controlled fermentation.

Biological samples (blood, stool, and urine) and lifestyle data were collected at baseline and after eight weeks. Participants were asked to maintain their usual diet and physical activity levels, monitored via the Food Frequency Questionnaire (FFQ) and the International Physical Activity Questionnaire (IPAQ).

Laboratory Analyses

The kombucha’s composition was assessed using:

• High-performance and ultra-performance liquid chromatography (HPLC & UPLC-MS)
• Titration and Folin–Ciocalteu colourimetric assays

Microbial profiling was performed via serial dilution techniques, and intestinal permeability was evaluated using lactulose/mannitol urinary ratios and plasma zonulin concentrations. Stool samples were also analysed for short-chain fatty acid (SCFA) content (acetate, butyrate, and propionate).

Key Findings

Kombucha Composition

The black tea kombucha was found to be rich in 145 phenolic compounds, comprising:

• Flavonoids (81%), notably quercetin 3-O-rutinoside
• Phenolic acids (19%)

These compounds are known for their antioxidant and potential anti-obesity properties.

Microbial Changes

The primary outcomes demonstrated a differential response between the normal-weight group and group with obesity:

• Participants with obesity exhibited:
  • Increased abundance of Subdoligranulum, a beneficial butyrate-producing bacterium
  • Reductions in Ruminococcus and Dorea, both genera associated with obesity and inflammation
• These reductions were particularly noteworthy as both Ruminococcus and Dorea were initially present at significantly higher levels in participants with obesity, but were brought down to baseline levels seen in the normal-weight group by the end of the intervention.
• In both groups, kombucha consumption supported the proliferation of:
  • Bacteroidota
  • Akkermanciaceae, both commensal bacterial families associated with improved metabolic health

Fungal Composition

Although kombucha also altered the gut fungal profile, the effects were less conclusive:

• A modest increase in Saccharomyces was observed
• No significant overall change in fungal alpha-diversity
• Participants with obesity had higher fungal diversity at baseline, which may have declined or shifted over the intervention period

Intestinal Permeability and SCFAs

Despite notable microbial shifts, no statistically significant differences were found in:

• Short-chain fatty acid concentrations in stool samples (acetate, butyrate, propionate)
• Intestinal permeability markers, including:
  • Lactulose-to-mannitol urinary ratio
  • Plasma zonulin levels

This suggests that while the microbiome composition changed, functional and physiological biomarkers remained largely unaltered over the eight-week period.

Physical Activity

IPAQ results confirmed that physical activity levels remained consistent throughout the study. This minimises confounding and supports that observed microbiota changes are likely due to the kombucha intervention rather than lifestyle alterations.

Study Limitations

Several limitations are worth noting:

• Lack of a control group: All participants consumed kombucha, meaning that outcomes cannot be compared to a non-intervention group.
• Short duration: Eight weeks may not be sufficient to observe changes in SCFA production or gut barrier function.
• Sample size: While relatively robust for a pilot nutritional intervention, broader generalisations require larger and more diverse cohorts.
• Self-reported data: Dietary intake and activity levels were self-reported and may be subject to bias or inaccuracies.

Conclusions and Future Directions

This study offers promising early evidence that black tea kombucha consumption can beneficially modulate the gut microbiota, especially in people living with obesity. The findings suggest that kombucha may help rebalance the gut microbial ecosystem by increasing beneficial bacteria and reducing those associated with metabolic dysfunction.

However, the absence of changes in SCFA levels and intestinal permeability markers indicates that microbial compositional changes may not immediately translate into functional physiological benefits within the timeframe observed.

Future research should include:

• A randomised control group for comparison
• A longer intervention duration to detect slower-acting effects
• Clinical endpoints such as weight change, lipid profile, and inflammatory markers to better understand the therapeutic potential of kombucha in obesity management

In summary, daily black tea kombucha consumption over eight weeks resulted in favourable changes to the gut microbial landscape, particularly for individuals with obesity. While more comprehensive studies are needed, these findings contribute to the growing evidence base linking fermented foods to gut and metabolic health.

CCH Insight:

This is a very interesting study, but it raises lots more questions about fermented foods, the gut microbiome and obesity than it answers. The fact that just one drink of kombucha per day can positively influence the balance of the gut microflora in relation to obesity is excellent news, but longer-term studies with more participants are needed to see if kombucha can bring about meaningful metabolic changes. And what about other fermented foods, like kefir, yoghurt, sauerkraut and kimchi? Could they also have positive effects, both individually and synergistically? This is a fascinating area of research, which we follow with great interest at CCH.

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