Obesity Medications Work Best for Young People When Combined With Lifestyle Support
Key Takeaways:
- Among young people with obesity, pairing medication with structured behavioural and lifestyle support produced the largest short-term reductions in BMI.
- Metformin combined with behaviour and lifestyle treatment lowered BMI by 4.95, whereas metformin used on its own showed no significant change.
- Semaglutide plus counselling was linked to the biggest BMI reduction of any approach, although this estimate rested on a single trial.
Support matters as much as the medicine
Children and adolescents with obesity who received a combination of medication and structured lifestyle treatments achieved the greatest short-term reductions in BMI, according to a new evidence synthesis. The findings point away from prescribing in isolation and towards a model in which medication is layered on top of behavioural and family support rather than used as a stand-alone fix.
How the study was conducted
Researchers carried out a systematic review and network meta-analysis, searching the literature databases through June 2025, to work out which obesity treatments perform best for young people. A network meta-analysis allows multiple interventions to be compared against one another even where they have not all been tested head-to-head in the same trial.
The final analysis brought together 42 randomised clinical trials involving 3835 participants aged 10–19 years with obesity. The median age was 14.5 years, and 59.2% of participants were female individuals. Most of the included studies followed up participants over 6–12 months, placing the emphasis firmly on short-term outcomes.
The interventions assessed fell into several categories: structured behavioural and lifestyle treatments, in both standard and intensive forms; counselling; medications, including GLP-1 receptor agonists, metformin, orlistat, and phentermine–topiramate; and combinations of medication with lifestyle treatment.
The primary outcomes were changes in BMI and BMI z-score, while the secondary outcomes were changes in waist circumference, fat mass, and lean mass. The interventions were then ranked in order of effectiveness.
On study quality, the risk for bias was judged low in 21.4% of trials and high in 26.2%, with the remaining 52.4% raising some concerns. The overall certainty of the evidence ranged from very low to high, so the strength of the findings varies considerably from one comparison to another.
What the analysis found
Across the 35 trials that reported BMI and the 19 that reported BMI z-score, medications produced larger reductions when paired with lifestyle treatments than when used alone. Metformin illustrates the pattern clearly: combined with behaviour and lifestyle treatment it was associated with a reduction of 4.95 in BMI, whereas metformin used on its own showed no significant change in BMI.
Semaglutide plus counselling was associated with the largest reduction in BMI (mean difference [MD], −8.31) and in BMI z-score (MD, −1.80). This estimate, however, came from a single trial, so it should be read with caution.
Behavioural and lifestyle treatment on its own was associated with reductions in BMI (MD, −3.85; five studies) and in BMI z-score (MD, −0.89; one study) – results that matched or exceeded the effect of certain medications used alone. Combination treatments were linked to the largest reductions in fat mass, drawing on 21 studies.
What it means in practice
The authors framed the combined approach as consistently outperforming medication given without support. “[The] finding suggests that even combining medication with basic counselling was still superior to giving medication without any lifestyle support,” the researchers wrote. “Medications should never be prescribed in isolation; a person-centered, family-centered approach matching treatment intensity to medical need is essential,” they added.
Where the research came from
The study was led by Ke-wen Wan, MSc, of Hong Kong Baptist University in Hong Kong SAR, China. It was published online on 22 June in JAMA Pediatrics.
Limitations to consider
Several caveats temper the results. The findings for newer medications were based on only a few small trials, which limits confidence in those specific estimates. The wide age range may have obscured differences by age or stage of puberty, since a 10-year-old and a 19-year-old can respond very differently to the same intervention. Most of the trials also did not report data on race, ethnicity, or income, leaving open questions about how the findings apply across different populations.
Funding and disclosures
The study received funding from grants from Hong Kong Baptist University. One author reported serving on professional boards related to childhood obesity and receiving travel grants or reimbursements, and another author reported receiving consulting fees from pharmaceutical companies. Detailed disclosures are available in the original article.
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Air Pollution May Raise Obesity Risk in Children by Affecting Impulse Control
Key Takeaways:
- New peer reviewed research suggests early exposure to PM2.5 air pollution may contribute to childhood obesity by affecting children’s impulse control.
- Babies exposed to higher PM2.5 levels during their first year of life were more likely to show later difficulties with inhibitory control, which were linked to higher body fat and BMI between ages four and eight.
- Researchers say individual steps such as HEPA filtration may help reduce exposure, but wider policy action is needed to limit PM2.5 pollution.
Study links PM2.5 exposure with later weight gain
Exposure to common air pollution may contribute to childhood obesity by disrupting children’s ability to control impulses, according to new first of its kind peer reviewed research.
The study, led by researchers at Mount Sinai’s Icahn School of Medicine, focused on particulate matter 2.5, known as PM2.5. This pollutant is made up of microscopic solid or liquid particles suspended in the air. Common manmade sources include traffic emissions and the burning of fossil fuels.
PM2.5 is considered a probable carcinogen and has been linked to a range of health problems, including dementia and strokes. Previous research has also shown that PM2.5 has obesogenic properties, meaning it may disrupt metabolism and is associated with weight gain.
Impulse control identified as a possible pathway
Researchers said the new study is the first to identify impulse control as a potential pathway linking early PM2.5 exposure with childhood obesity.
The study found that babies exposed to higher levels of PM2.5 during their first year of life were more likely to develop difficulties with impulse control later in childhood. Those behavioural changes were then associated with higher body fat and higher BMI among children aged between four and eight.
“A lot of the obesity research primarily focuses on – and is being shaped by – diet and physical activity, and a lot may not include environmental exposures, including air pollution,” said Jamil Lane, a co-author with Mt Sinai’s Icahn School of Medicine.
“Our study is novel in that we are showing that high levels of air pollution early in life may cause more difficulty with self-regulation, which contributes to weight gain.”
Why early life exposure matters
The researchers examined data from 434 children born largely between 2007 and 2008 in Mexico City. The children are part of a longitudinal health study.
The authors modelled ambient PM2.5 exposure during pregnancy and during the children’s first year of life. Lane described this early period as a “very sensitive window” for brain development.
The children were later assessed for impulsivity and measures linked to obesity. According to the study, the group with the highest PM2.5 exposure showed a pattern of high impulsivity, reflecting significant deficits in inhibitory control.
How brain development and eating behaviour may be connected
Poor inhibitory control is already well established as being linked to obesity. Bob Wright, a study co-author and environmental epidemiologist at Mount Sinai, said the authors questioned whether PM2.5’s neurotoxic effects and obesity were “part of the same processes”.
“Our study shows that greater early exposure to PM2.5 in the first year of life is associated with alterations in inhibitory control function in childhood,” the study’s authors wrote. “The effect is likely due to altered eating behaviors related to inhibitory control that are programmed early in life.”
The findings suggest that air pollution exposure early in life may affect brain pathways involved in self-regulation, which could then influence eating behaviours and weight gain later in childhood.
Study limitations and wider context
The study acknowledges several limitations, including its small population size and limited covariates.
However, Cecilia Moura, a clean transportation scientist with the Union of Concerned Scientists, who was not involved in the research, said the study was sound and that the novel findings “indicate there is sufficient evidence supporting the correlation to motivate policies and regulations that mitigate exposure to PM2.5”.
The research comes against the backdrop of high levels of obesity in the United States. In 2018, about 42% of American adults were estimated to have obesity.
Steps families can take to reduce exposure
The researchers said people can take some steps to help protect themselves and their children from PM2.5 exposure.
Home HEPA air filtration systems are effective at removing PM2.5. Furnace filters rated MERV 13 or higher can also capture much of the pollutant. DIY filtration systems made with a box fan, cardboard, tape, and pleated air filters have also been shown to reduce particulate matter.
The authors advised parents to avoid high congestion areas as much as possible and to stay indoors when wildfire smoke is heavy.
Researchers call for policy action
Despite these individual measures, researchers stressed that people cannot fully protect themselves from air pollution exposure on their own. They said the findings underline the need for wider policy solutions and greater public awareness.
“There is not going to be change if people are not aware and lobbying for it, but policy change takes a long time and there are things we can do to protect ourselves,” Wright said.
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GLP-1 Medicines for Weight Loss Reach Record Use Among US Adults
Key Takeaways:
- Eleven per cent of US adults report currently taking GLP-1 medicines for weight loss in 2026, a substantial rise from three per cent in 2024.
- Awareness of GLP-1 medicines intended for weight loss has increased to 91 per cent, while the US adult obesity rate has declined from its 2022 peak of 39.9 per cent to 36.4 per cent so far in 2026.
- Brand-name GLP-1 medicines remain the most commonly used option, but cost and insurance coverage appear to be driving some people towards compounded or custom-mixed versions.
GLP-1 use for weight loss continues to rise
The proportion of US adults who say they are currently taking GLP-1 medicines for weight loss has reached a new high in 2026, according to data from the Gallup National Health and Well-Being Index.
Eleven per cent of US adults now report current use of these medicines for weight loss purposes. This represents a significant increase from 2024, when three per cent reported current use. Lifetime use has also risen, with 15 per cent of US adults saying they have taken a GLP-1 medicine for weight loss at some point. This is an increase of nine percentage points.
The findings are based on a web survey of 5,065 US adults conducted between 28 May and 5 June 2026. The survey used the probability-based Gallup Panel, which includes respondents from all 50 US states and the District of Columbia.
How Gallup measured GLP-1 use
To assess whether people had ever used GLP-1 medicines for weight loss, Gallup asked respondents:
“Have you ever taken weight loss medications such as semaglutide (brand names Ozempic and Wegovy), liraglutide (brand name Saxenda) or tirzepatide (brand names Mounjaro and Zepbound)?”
People who answered “yes” were then asked a follow-up question to determine whether they were currently taking one of these medicines:
“Are you currently taking weight loss medications such as semaglutide (brand names Ozempic and Wegovy), liraglutide (brand name Saxenda) or tirzepatide (brand names Mounjaro and Zepbound)?”
These questions allowed Gallup to distinguish between lifetime use and current use among US adults.
FDA approvals have expanded the market
The rise in GLP-1 use follows the approval of several medicines for weight loss in the US. The Food and Drug Administration approved Novo Nordisk’s Wegovy, which contains semaglutide, for weight loss in 2021.
Since then, additional options have become available. Eli Lilly’s Zepbound, which contains tirzepatide, received FDA approval in November 2023.
As more treatment options have entered the market, public awareness has also increased. Gallup reports that 91 per cent of Americans are now aware of GLP-1 medicines intended for weight loss, up from 80 per cent in 2024.
Adult obesity has declined from its 2022 peak
Gallup’s latest findings show that the US adult obesity rate has continued to fall after reaching a record high of 39.9 per cent in 2022. So far in 2026, the adult obesity rate stands at 36.4 per cent.
Gallup describes this as a statistically meaningful decline. The trend has continued to move in the opposite direction to national GLP-1 use, which has increased over the same period.
Gallup calculates obesity using the federal standard of a body mass index of 30 or higher. BMI is calculated using respondents’ self-reported height and weight.
The organisation notes that self-reported data may produce somewhat lower estimates than studies based on randomised clinical measurements of height and weight. Gallup suggests that a “vanity effect” in how people report their own height and weight may help explain this difference. However, because Gallup has used a consistent method over time, the data still provides useful information about changes in the adult obesity rate.
Diabetes diagnoses have levelled off
While obesity levels have declined, the proportion of US adults who report having been diagnosed with diabetes has remained steady since 2023. This follows 15 years of gradual increases that occurred alongside rising obesity rates.
Gallup notes that a falling obesity rate would be expected to stabilise, but not necessarily reduce, the proportion of adults who have ever been diagnosed with diabetes. Diabetes is described in the original analysis as a lifelong disease that can be managed but not cured.
To measure diabetes prevalence, Gallup asked US adults:
“Has a doctor or nurse ever told you that you have diabetes?”
The diabetes rate includes people with Type 1 diabetes and people with Type 2 diabetes. The 2026 figures for obesity and diabetes are based on 10,091 respondents from surveys conducted from 18 February to 3 March and from 28 May to 5 June 2026.
Brand-name GLP-1 medicines remain the most common option
Among adults currently taking GLP-1 medicines for weight loss, brand-name options remain the most common.
Gallup found that 68 per cent of current use involves brand-name GLP-1 medicines such as Ozempic or Wegovy. By comparison, 19 per cent of current use involves compounded or custom-mixed versions of the medicine.
A further 12 per cent of people currently taking a GLP-1 medicine for weight loss are unsure whether they are using a brand-name medicine.
People using compounded versions report slightly higher effectiveness
Gallup also compared perceived effectiveness between people taking brand-name GLP-1 medicines and those taking compounded or custom-mixed versions.
People using compounded or custom-mixed GLP-1 medicines were slightly more likely to describe the medicine as “extremely effective”. Thirty-nine per cent of people in this group gave that response, compared with 32 per cent of people using brand-name GLP-1 medicines.
However, both groups generally regarded the medicines as effective. Seventy-seven per cent of people using compounded or custom-mixed versions said the medicine was either “effective” or “extremely effective”. Among people using brand-name GLP-1 medicines, the figure was 74 per cent.
Some people are switching from brand-name to compounded GLP-1 medicines
Although brand-name medicines continue to account for most current GLP-1 use, Gallup’s findings suggest that compounded or custom-mixed versions are gaining ground.
Among people currently using compounded or custom-mixed GLP-1 medicines, 35 per cent report having switched from a brand-name medicine. By contrast, 10 per cent of people currently using brand-name GLP-1 medicines say they switched from a compounded or custom-mixed version.
This suggests that movement towards compounded or custom-mixed GLP-1 medicines is greater than movement in the opposite direction.
Cost and insurance coverage appear to be major factors in this shift. Among people who switched from a brand-name GLP-1 medicine to a compounded version, 66 per cent cited cost or insurance coverage as their main reason for switching. Among those who switched from a compounded version to a brand-name medicine, 34 per cent cited cost or insurance coverage as the primary reason.
Wider implications for obesity and diabetes trends
The growing use of GLP-1 medicines for weight loss may point to broader health implications for adults in the US. Gallup’s analysis indicates that increased use of these medicines has coincided with a decline in the adult obesity rate and a levelling off in diabetes diagnoses after years of increases.
Previous research cited in the original analysis has shown a general alignment between GLP-1 use and declining obesity rates across age groups. One exception is adults aged 65 and older, among whom the reported effectiveness of GLP-1 medicines is lower.
Brand-name GLP-1 medicines still lead the market by a wide margin. However, the lower cost of compounded or custom-mixed versions appears to be contributing to a shift away from brand-name options for some people. This may be expanding access to GLP-1 medicines across broader sections of the population, although access remains limited.
Gallup suggests that this broader availability may be one factor helping to drive overall GLP-1 use higher in the US.
Source: Gallup
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Intermittent Fasting Maintains Long-Term Weight Loss Irrespective of Meal Timing, Study Shows
Key Takeaways:
- Adults living with overweight or obesity who followed a 16:8 fasting pattern for 12 weeks kept off significantly more weight a full year after the intervention ended.
- The benefit held whether the eight-hour eating window fell early or late in the day, giving people the freedom to fit fasting around their own routines.
- One in three participants chose to carry on fasting unprompted during the follow-up year, pointing to a habit that is relatively easy to sustain.
A twelve-week habit with lasting results
New research has shown that confining daily food intake to an eight-hour window helps people living with overweight or obesity maintain their weight loss 12 months after a structured intervention comes to an end. The work was carried out by scientists from the University of Granada (UGR), the Granada Institute for Biomedical Research (ibs.GRANADA), the Public University of Navarra and the Biomedical Research Networking Center (CIBER), and was recently published in the journal Clinical Nutrition.
The trial followed 99 adults, half of them women, all of whom were living with overweight or obesity. It focused on intermittent fasting, and specifically the approach widely known as 16:8, in which people fast for 16 hours and eat only during the remaining eight. The findings indicate that this pattern is an effective way to hold on to weight loss over the medium term.
Crucially, the researchers found that the benefits endured a year later regardless of when the eating window fell. Whether participants ate early in the day, between 9 a.m. and 5 p.m. (early fasting), or later on, between 1 p.m. and 9 p.m. (late fasting), they fared better than people who kept to their usual routine of eating across a window of 12 hours or more. Both the early- and late-fasting groups sustained significantly greater weight loss at 12 months, and the early-fasting group also held on to a greater reduction in fat mass. According to the team, this suggests that the approach is not only feasible and effective in the short term but also produces effects that last.
Body composition assessed one year later
For the first 12 weeks, participants were split into four groups, each of which took part in a Mediterranean diet education programme. A control group kept its usual eating window of 12 hours or longer. An early-fasting group used an eight-hour window that began before 10 a.m., while a late-fasting group used an eight-hour window that started after 1 p.m. A fourth, self-selected group chose its own eight-hour window.
Weight, fat mass and fat-free mass were measured before and after the 12-week intervention, and again a year after the study finished. The work forms part of a larger project whose principal results appeared in the journal Nature Medicine. That analysis found that people who practised time-restricted eating (TRE), whatever their eating schedule, lost an average of 3–4 kilograms (6.6–8.8 pounds) more than those given nutritional advice alone.
Dr Alba Camacho Cardeñosa, a researcher at the University Joint Institute for Sport and Health (iMUDS) at the University of Granada and a postdoctoral fellow at ibs.GRANADA in the Endocrinology and Nutrition Department at San Cecilio University Clinical Hospital, is the study’s first author. She explains that “to date, although we knew that intermittent fasting promotes modest weight loss in the short term, it was unclear whether its effects were sustained over time. By evaluating the participants 12 months after the intervention ended, we demonstrated that the changes in body weight persist.”
The researchers also point to the strength of ongoing adherence, noting that “a very positive finding is that one in three people decided to continue practicing intermittent fasting on their own during that year of follow-up, suggesting that it is a relatively easy habit to integrate into daily life.”
A flexible strategy against obesity
The study was led by researchers from ibs.GRANADA belonging to the PROFITH CTS-977 research group at the University of Granada, headed by Professor Jonatan Ruiz Ruiz. It was conducted in collaboration with the San Cecilio University Clinical Hospital and the Virgen de las Nieves University Hospital in Granada, the Public University of Navarra, the CIBER on Obesity (CIBEROBN) and the CIBER on Frailty and Healthy Aging (CIBERFES).
The team emphasises that as little as 12 weeks of intermittent fasting may serve as an effective medium-term strategy for weight management in adults living with overweight or obesity. Because both early- and late-day regimens proved effective, the findings give people the flexibility to choose the schedule that best fits their lifestyle, which may in turn improve adherence and support more successful obesity treatment.
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Statins Bring Many People With Obesity Level With Healthy-Weight Peers on Cholesterol and Blood Pressure, Study Finds
Key Takeaways:
- Among adults over 40 in high-income countries, gaps in cholesterol and blood pressure between people with obesity and those of a healthy weight have narrowed or vanished.
- The convergence is driven largely by wider use of statins and blood-pressure medications among people living with obesity.
- In adults under 40, people with obesity still show higher cholesterol and blood pressure, and obesity continues to raise the risk of other conditions.
A narrowing gap in cardiovascular risk
Many adults living with obesity now have cholesterol and blood pressure readings that are “indistinguishable” from those of people at a healthy weight, largely because of the use of statins, a major new study has found. In some cases, researchers reported, people with obesity were “better off” than their healthy-weight counterparts.
Historically, adults with obesity were more likely to have raised blood pressure and higher levels of unhealthy cholesterol. The study found, however, that differences in unhealthy cholesterol and blood pressure have “narrowed or disappeared” among people aged 40 and over.
Experts attribute the shift chiefly to the greater use of cholesterol-lowering medications, such as statins, and blood-pressure treatments – both of which are more commonly prescribed to people living with obesity. They said the findings were important to “give a picture of the cardiovascular health” of the population most likely to be offered weight-loss medications, whose popularity has risen rapidly, and warned that it was important not to “lose sight” of these results as more people take such drugs.
What the researchers examined
The study, published in the Lancet, drew on data from almost 1 million adults aged 20 to 79 across England, Japan, South Korea, Taiwan, Thailand, Finland and the United States. Researchers analysed blood pressure, cholesterol levels and body mass index (BMI) scores recorded in 110 health surveys carried out between 1990 and 2024. They also reviewed the use of cholesterol-lowering drugs and blood-pressure treatments, known as antihypertensives.
The team found that unhealthy cholesterol levels and blood pressure “declined over time”, particularly among people aged 40 and over. Those declines were larger among people with obesity, “leading to a convergence of these risk factors between obesity and normal BMI in people older than 40 years”.
The researchers wrote: “As a result of these trends, in England, the US, Thailand, South Korea, and Japan, older people with obesity often became indistinguishable from, or better off than, those with normal BMI in terms of non-HDL cholesterol and SBP (systolic blood pressure).”
They added: “We found that differences in non-HDL cholesterol and SBP between those with obesity and those with a normal BMI narrowed or disappeared, especially in older adults, in some cases making those with and without obesity indistinguishable in terms of these cardiometabolic traits.”
Why the gap has closed
Prof Majid Ezzati, from the School of Public Health at Imperial College London, said: “Our study suggests that, in high-income countries, taking medication to lower blood pressure and cholesterol has helped middle-age and older adults lower their cardiovascular risk to levels that are similar to people with normal BMI [body mass index].
“At a time that weight-loss medications are becoming more widely used, our results give a picture of the cardiovascular health of people likely to be prescribed them, which allows the healthcare system to understand how blood pressure and cholesterol treatments benefit the population alongside weight-loss medications.”
Younger adults remain at higher risk
The convergence was not seen across all age groups. In adults under 40, people with obesity still had higher levels of unhealthy cholesterol and higher blood pressure than their healthy-weight peers.
One of the research team, Prof Edward Gregg from Imperial College London, stressed that “it doesn’t mean that obesity does not still increase your risk of other outcomes”.
Another of the authors, Yse d’Ailhaud de Brisis, also from Imperial College London, said: “While good news for older adults with obesity, our results suggest that cardiovascular health risks remain higher for adults under 40 than for their counterparts with a normal BMI.
“Early lifestyle interventions, screening and, when appropriate, medication in this younger group should be considered to prevent long-term cardiovascular complications linked to obesity.”
A public health success, with caveats
Commenting on the study, Prof Bryan Williams, the chief scientific and medical officer at the British Heart Foundation, said: “This study highlights a powerful public health success story – it shows just how effective modern treatments for blood pressure and cholesterol have become, with many people over 40 with obesity now reaching levels similar to those with a healthy weight.
“But we must not lose sight of the bigger picture. These medications are needed because of the adverse effects of obesity on cardiovascular disease risk. Moreover, obesity still affects the body in many other ways and increases the risk of other health problems, including diabetes, kidney disease and some cancers.”
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Many Who Stop GLP-1 Medications Restart Within a Year, Study Finds
Key Takeaways:
- Around 4 in 10 people with type 2 diabetes stopped their GLP-1 medication within the first year, rising to nearly 6 in 10 by the end of two years.
- Of those who stopped, more than half restarted within a year and nearly two-thirds within two years, suggesting use is often start-and-stop rather than permanent.
- Newer medications, a prescription from an endocrinologist, and fewer stomach-related side effects were all linked to a lower likelihood of stopping.
Use is more start-and-stop than assumed
People prescribed GLP-1 medications are more likely to start and stop treatment than many assume, according to a study being presented on Sunday at ENDO 2026, the Endocrine Society’s annual meeting in Chicago, Illinois.
“Our study asked two questions that haven’t been well answered until now: How many people with type 2 diabetes taking GLP-1 medications actually stop using them? And how many restart them?” said Sainikhil Sontha, M.S., a research associate at Boston University School of Public Health in Boston, Massachusetts.
How the study was carried out
The researchers ran a retrospective cohort study using Komodo Health US claims data covering January 2019 to June 2025. The group included adults aged 18 to 64 years with a BMI of 25 kg/m² or above and type 2 diabetes who had started liraglutide, semaglutide, or tirzepatide, and who had previously enrolled within the last year with more than six months of follow-up.
Discontinuation was defined as a gap of more than 60 days in filling a GLP-1 prescription. Obtaining a new fill after discontinuation was counted as reinitiation.
How many people stopped
“Using insurance records from more than 60,000 Americans with type 2 diabetes, we found that about 4 in 10 patients stopped their GLP-1 medication within the first year, and nearly 6 in 10 had stopped by the end of two years,” Sontha said.
But the team also found something more encouraging.
How many people restarted
“More than half of those who stopped restarted therapy within a year (41.5%), and nearly two-thirds did so within two years (58%),” Sontha said. “This suggests that for many patients, these medications aren’t being abandoned permanently; use is more start-and-stop than most people assumed.”
Who was more likely to stop
Using Cox proportional hazards models, the researchers also accounted for sociodemographic, clinical, and provider-level predictors.
Sontha and colleagues found that people on Medicaid or Medicare, people who are Black, and those experiencing nausea or other stomach-related side effects (37%) were more likely to discontinue a GLP-1 medication within a year.
What was linked to staying on treatment
People were 10% less likely to stop if their first GLP-1 medication was prescribed by an endocrinologist.
The type of medication also made a difference. People taking newer medications such as tirzepatide were 41% less likely to discontinue than those taking older drugs such as liraglutide, while people taking semaglutide were 28% less likely to discontinue anti-obesity medication use than those on older medications.
Why it matters
“This research matters because consistent use of these medications is what produces their protective effects,” Sontha said. “Stopping early may mean missed opportunities to prevent heart attacks, kidney disease progression and other complications.”
The researchers hope the findings give providers, insurers, and policymakers a clearer picture of which patients need more support to stay on GLP-1 medications.
Source: Endocrine Society
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Maternal Obesity Before Pregnancy Tied to 64% Higher Childhood Obesity Risk
Key Takeaways:
- Children whose mothers had obesity before pregnancy were 64% more likely to be affected by overweight or obesity by age 3.
- Gaining excess weight during pregnancy – common among about 41% of mothers studied – was linked to a 39% higher risk.
- Maternal weight factors mattered at different stages, and the links varied between Hispanic and non-Hispanic families.
The roots of childhood obesity may begin in the womb
New research led by the George Mason University College of Public Health has found that children whose mothers began pregnancy with obesity were 64% more likely to be affected by overweight or obesity by age 3. Excessive weight gain during pregnancy was associated with a 39% increase in that risk.
“Our findings suggest that childhood obesity risk may not develop in a single, uniform way, but maternal health before and during pregnancy may play a larger role than many people realize,” said study lead author Hua Min, associate professor in the Department of Health Administration and Policy.
Timing appears to matter
Different pregnancy-related weight factors appeared to matter at different stages. Excess weight gain during pregnancy was more closely linked to infant weight, while maternal obesity was more strongly associated with weight later in toddlerhood. Researchers also found that excess weight gain during pregnancy was common, affecting about four in 10 mothers in the study.
A large, ethnically diverse US study
Published in the International Journal of Obesity, the research is among the largest and most ethnically diverse longitudinal studies in the United States to examine how maternal weight may influence obesity risk in early childhood. Researchers tracked nearly 3,000 mother-child pairs, drawing on data from a Northern Virginia birth cohort taking part in the National Institutes of Health’s Environmental influences on Child Health Outcomes (ECHO) Program.
The George Mason research team included Michael S. Bloom of the Department of Global and Community Health, along with Grace Lawrence, Alma Fuller and Kathi C. Huddleston of the School of Nursing.
Why this matters
Childhood obesity remains one of the most pressing health challenges in the United States. The study notes that nearly 90% of children with obesity at age 3 will continue to be affected by overweight or obesity into early adulthood. Those early patterns can carry long-term consequences, increasing the risk of diabetes, cardiovascular disease and other chronic health problems.
Researchers say the findings reinforce the importance of maternal health before and during pregnancy – not just for pregnancy outcomes, but also for a child’s long-term health trajectory. The findings also suggest that obesity risk may develop differently across populations, with patterns varying among demographic groups.
Study details
The findings were based on the First Thousand Days of Life Study, a Northern Virginia birth cohort taking part in the ECHO Program, which examines how early-life experiences affect child health. George Mason was selected as an ECHO research site in 2019.
Researchers enrolled 2,899 mother-child pairs in Northern Virginia between 2012 and 2019, following families from pregnancy through to age 3.
Key findings
The strongest signal came from maternal weight before conception. Children whose mothers had obesity before pregnancy were 64% more likely to be affected by overweight or obesity by age 3, and the risk rose incrementally with weight: for every one-point increase in maternal pre-pregnancy body mass index (BMI), the likelihood of childhood overweight or obesity climbed by about 4%.
Weight gain during pregnancy carried its own, separate risk. Children whose mothers gained excessive weight while pregnant were about 39% more likely to be affected by overweight or obesity by age 3, and roughly 41% of mothers in the study gained more than national guidelines recommend. Notably, the two factors seemed to act at different points in early life: excess weight gain during pregnancy showed stronger links to higher weight in infancy, whereas maternal weight before pregnancy became more strongly associated with higher child weight later in early childhood. The associations also differed between Hispanic and non-Hispanic families, suggesting that obesity risk may develop differently across populations.
Looking ahead
Taken together, the findings point to the period before and during pregnancy as a meaningful window for a child’s long-term health, rather than a single moment or cause. Because the maternal weight factors appeared to matter at different stages, and because the associations varied between demographic groups, the researchers suggest that efforts to understand and address childhood obesity may need to account for how risk builds over time and how it differs across populations.
Source: George Mason University
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A Simple Blood Test Could Identify the Most Effective Obesity Medication
Key Takeaways:
- A hypothesis-generating pilot study suggests that fasting blood levels of two incretin hormones – GLP-1 and GIP – may help predict how well people with severe obesity respond to semaglutide and tirzepatide.
- Low fasting GIP was linked to an optimal response to tirzepatide, while low GLP-1 combined with intermediate-to-high GIP was linked to an optimal response to semaglutide.
- The researchers stress that the findings are preliminary and should not guide prescribing until confirmed in larger, adequately powered randomised trials.
A step towards matching patients with the right medication
A straightforward fasting blood test may one day help clinicians decide which obesity medication is most likely to work for an individual patient. That is the tentative conclusion of a new hypothesis-generating pilot study published in the journal Diagnostics, which reports that fasting blood levels of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) may help predict the therapeutic response to semaglutide and tirzepatide in people living with severe obesity.
Why obesity medications produce different responses
Obesity, characterised by excessive fat accumulation in the body, has become a global epidemic, affecting more than 650 million adults worldwide. The condition is associated with a significantly increased risk of cardiovascular disease, type 2 diabetes, certain cancers, and all-cause mortality.
Among the pharmacological options, glucagon-like peptide-1 receptor agonists (GLP-1RAs) such as semaglutide, and dual GIP/GLP-1 receptor co-agonists such as tirzepatide, have shown considerable promise in addressing this challenge. One major limitation of these medicines, however, is the marked variability in response between individuals, which has prompted interest in identifying the biological mechanisms that drive this variation.
GLP-1 and GIP are the two principal incretin hormones, secreted by intestinal cells after food is eaten. GLP-1 suppresses appetite and promotes satiety through central nervous system pathways, whereas GIP regulates adipose tissue metabolism and energy expenditure. Acting synergistically, these hormones help to regulate glucose metabolism and appetite, giving them a major role in the management of obesity and type 2 diabetes.
Because the incretin system is frequently dysregulated in obesity, researchers at the University of Catania and MEDISAN, both based in Italy, designed the study to investigate whether fasting blood levels of GLP-1 and GIP could help identify people more likely to respond to semaglutide and tirzepatide.
How the pilot study was designed
The study enrolled 90 adults with a BMI greater than 40 kg/m² (class III obesity). Fasting blood samples were collected to measure each participant’s GLP-1 and GIP levels.
Each hormone was independently divided into low, intermediate, and high tertiles – a statistical division of a dataset into three equal parts – based on its distribution across the study population. Combining the GLP-1 and GIP tertiles produced nine distinct hormone profiles, each containing 10 participants. Within every profile, participants were randomly assigned to receive either semaglutide or tirzepatide, with five people allocated to each medicine per profile.
Response to treatment was assessed at six months. A reduction in body weight of less than 5% was classed as a low response, a reduction of 5–15% as an intermediate response, and a reduction of more than 15% as an optimal response.
Low incretin levels shaped treatment outcomes
The analysis showed that participants in the three profiles characterised by the low GIP tertile achieved an optimal response to tirzepatide, regardless of their GLP-1 levels. This suggests that low fasting GIP was associated with greater responsiveness to exogenous GIP receptor agonists such as tirzepatide.
For semaglutide, participants in two profiles – those characterised by a low GLP-1 tertile combined with an intermediate-to-high GIP tertile – were the only ones to achieve an optimal response. This may indicate that low endogenous GLP-1 availability leaves more GLP-1 receptors free for activation by exogenous semaglutide. The intermediate-to-high levels of endogenous GIP, meanwhile, may point to intact or compensatory incretin secretory capacity that does not interfere with the efficacy of a GLP-1 receptor agonist.
Participants in the profile characterised by high GLP-1 and high GIP tertiles achieved only a low response to both medicines. The authors suggest this may reflect a dysregulated incretin system that was not overcome by pharmacological doses within six months. They note, however, that fasting hormone measurements alone cannot distinguish between incretin secretory deficiency and receptor resistance, making this interpretation speculative.
On the clinical side, participants who achieved an optimal response to either medicine experienced significant reductions in waist circumference and improvements in insulin sensitivity. These changes paralleled the weight-loss patterns observed across the response groups, indicating clinically meaningful improvements in central adiposity and metabolic health.
How receptor occupancy may explain the findings
The observed variation in response may be explained through incretin receptor occupancy. Tirzepatide, as a dual GIP/GLP-1 receptor co-agonist, activates both receptor systems simultaneously. When GIP is present at low abundance (low fasting levels), it cannot fully occupy its receptor, potentially leaving that receptor available for exogenous tirzepatide. Once bound and activated, tirzepatide may then exert greater therapeutic effects by regulating adipose tissue metabolism, energy expenditure, and potentially central appetite regulation.
Semaglutide, which binds and activates the GLP-1 receptor exclusively, may exert its greatest effects when GLP-1 receptors are relatively unoccupied because of low levels of endogenous GLP-1. In these conditions, semaglutide may more effectively restore GLP-1 receptor signalling and deliver its anorectic, insulinotropic, and metabolic effects.
What this could mean for personalised prescribing
Taken together, the study suggests that fasting blood levels of GLP-1 and GIP were associated with the therapeutic response to semaglutide and tirzepatide in people with severe obesity, and may help identify those more likely to respond to treatment. Specifically, low GIP levels were associated with an optimal tirzepatide response, whereas low GLP-1 levels combined with intermediate-to-high GIP levels were associated with an optimal semaglutide response.
Because a single-timepoint measurement of GLP-1 and GIP cannot reveal receptor resistance, the researchers recommend treating these observations as hypothesis-generating, and highlight the need for mechanistic validation through dynamic measurements of incretin levels and receptor activity. Overall, the findings offer preliminary clinical evidence for incretin-guided, personalised pharmacotherapy that could improve treatment outcomes in obesity management.
Limitations and next steps
Several important caveats apply. This was a small, single-centre, open-label pilot study, with only five participants per treatment arm within each hormone profile. In addition, fasting hormone measurements cannot distinguish incretin secretory deficiency from receptor resistance. The authors therefore emphasise that the findings are preliminary and should not guide clinical practice until they are confirmed in larger, adequately powered randomised trials.
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Visceral Fat and Biological Ageing: New Research Links Deep Belly Fat to Faster Cellular Ageing
Key Takeaways:
- A study of nearly 4,800 adults aged 45 to 69 from the Busselton Healthy Ageing Study found that higher levels of visceral fat – the fat stored deep within the abdomen – were associated with faster biological and cellular ageing in both men and women.
- Among female participants, greater visceral fat was also linked to shorter telomere length, a recognised marker of cellular ageing.
- The associations held even after researchers adjusted for overall body fat, body mass index (BMI), waist circumference and lifestyle factors, suggesting visceral fat exerts an effect beyond general measures of body composition.
New research from The University of Western Australia suggests that visceral fat, the type of fat stored deep within the abdominal cavity and wrapped around internal organs, may contribute to faster biological ageing in middle-aged adults independently of overall body weight or general obesity measures. The findings were published in the journal Obesity.
A large population-based analysis
The study was co-authored by Adjunct Associate Professors Jennie Hui and Kun Zhu, both of The University of Western Australia, with the analysis led by Mr Riorden O’Shea, a resident medical officer with the WA Country Health Service. Researchers drew on data from nearly 4,800 participants – 2,614 of them women – aged between 45 and 69 years, all enrolled in the Busselton Healthy Ageing Study.
The team examined how visceral fat related to markers of biological ageing, including indicators of cellular ageing such as telomere length. Telomeres are the repetitive DNA sequences that cap the ends of chromosomes; their progressive shortening over time is widely regarded as a key biological signature of cellular ageing.
The analysis found that greater visceral fat was associated with accelerated biological ageing in both men and women. In women, higher visceral fat was additionally linked to shorter telomere length.
“Our study shows that visceral fat is associated with faster biological and cellular ageing,” said Associate Professor Hui, who is Director of the Busselton Health Study Laboratory. “Understanding what drives faster ageing helps us find better ways to stay healthy for longer.”
An effect that holds after adjusting for other body measures
A central finding of the study is that the link between visceral fat and accelerated ageing persisted even when researchers controlled for other indicators commonly used to assess body composition and adiposity.
“Importantly, these associations remained significant even after accounting for overall body fat, body mass index, waist circumference and lifestyle factors,” Associate Professor Zhu said.
This suggests that visceral fat may have implications for ageing that are not fully captured by routine measures such as BMI or waist circumference – measures that have long been criticised for failing to distinguish between fat stored just under the skin and the metabolically distinct fat located deep within the abdomen.
Why visceral fat behaves differently
Visceral fat is biologically active in ways that subcutaneous fat is not. It secretes inflammatory signalling molecules and contributes to a chronic, low-grade inflammatory state that researchers have increasingly linked to chronic disease and accelerated ageing.
“Visceral fat is metabolically active, secreting a range of pro-inflammatory proteins, which contribute to systemic inflammation and metabolic stress,” Associate Professor Zhu said.
She also noted a practical point that is likely to resonate in clinical settings: visceral fat does not require specialised, costly imaging to assess. “It can be easily measured using imaging technology, which is widely used in routine bone density scans,” she said. This positions visceral fat as a metric that could plausibly be folded into existing clinical workflows without significant additional cost.
The value of long-running cohort data
The findings rest on one of the most established population-health datasets in the world. Established in 1966, the Busselton Health Study is internationally recognised as one of the longest-running population health programmes ever conducted, providing a rich longitudinal dataset that continues to support research into chronic disease and healthy ageing.
Mr O’Shea, who led the analysis, said the project demonstrated the enduring scientific value of sustained cohort studies of this kind. “Access to high-quality longitudinal data allowed us to better understand how clinical risk factors relate to long-term health outcomes,” he said.
Implications for healthier ageing
The findings reinforce a growing body of evidence that abdominal fat distribution – not just total body fat – is an important consideration in healthy ageing. While the study is observational and does not establish that reducing visceral fat will directly slow ageing, the authors argue the results support the case for targeting abdominal fat as part of broader strategies to promote healthier ageing in middle and later life.
For clinicians, the practical takeaway is that visceral fat may warrant attention even in people whose BMI or waist circumference appears unremarkable, and that the imaging tools needed to measure it are already widely available in routine care.
The study, “Visceral fat is associated with accelerated biological and cellular ageing,” is published in Obesity.
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Will Wider Use of GLP-1s Mean Fewer Pills for Older Adults? Yale Study Offers a Reality Check
Key Takeaways:
- Yale researchers found that roughly 15% of polypharmacy cases in adults aged 65 and older – about 3.3 million of 22 million – are attributable to obesity.
- GLP-1 medications are unlikely to meaningfully reduce overall prescription burden in this age group, and their side effects may add further medications.
- From July, eligible Medicare beneficiaries will gain broad access to GLP-1s for obesity treatment under a federally funded demonstration programme running until December 2027.
Rethinking the promise of GLP-1s in geriatric care
As people grow older, they tend to accumulate chronic conditions, many of which require ongoing pharmacological management. While prescription medications play an essential role in disease control, polypharmacy – generally defined as the regular use of five or more drugs – carries a heightened risk of adverse effects, drug–drug interactions, and contraindications. With glucagon-like peptide-1 receptor agonists (GLP-1s) now reshaping obesity care, an open question has emerged: could effectively treating obesity in older adults reduce the number of medications they need overall?
A new study from Yale, published in the Journal of General Internal Medicine, sets out to answer that question by quantifying how much polypharmacy in adults aged 65 and older can be attributed to obesity in the first place.
The theory being tested
The investigators were motivated by a hypothesis that has gained traction in recent years: that better treatment of obesity could cascade into reduced reliance on medications for obesity-related complications such as type 2 diabetes, hypertension, and dyslipidaemia.
“Some in the medical community have theorized that if older adults are treated with GLPs, they can be on fewer medications because we’re treating their obesity and thereby treating other obesity-related conditions,” says Alissa Chen, MD, MPH, instructor of medicine (general medicine) and first author of the study.
To test the assumption, the team examined the extent to which polypharmacy in adults aged 65 and older could be statistically attributed to obesity.
What the study found
The researchers determined that approximately 15% of polypharmacy cases in this population were attributable to obesity. In absolute terms, this represented around 3.3 million of an estimated 22 million cases.
“While that is a lot of patients, there’s certainly a large majority of polypharmacy cases which are not attributable to obesity,” Chen adds.
The implication is significant. Even if GLP-1 therapy proves highly effective at treating obesity and its complications in older adults, the broader medication burden in this age group is driven largely by factors unrelated to body weight. As a result, GLP-1s are unlikely to substantially reduce the total number of prescriptions taken by people aged 65 and over, although they may still meaningfully improve obesity-related health outcomes.
A crossroads for obesity medications in older adults
Research into the use of obesity medications in older adults remains limited, and the long-term implications of widespread GLP-1 prescribing in this population are not yet well understood.
“We’re at a crossroads for the use of obesity medications like GLPs in older adults. This study gives us a first glimpse into one way in which GLPs may change the face of health and healthcare for older adults,” says Alexandra M. Hajduk, PhD, MPH, research scientist (geriatrics) and senior author of the study.
Chen also points out that the side-effect profile of GLP-1 therapy is itself worth considering when projecting medication burden. Common adverse effects, including nausea, acid reflux, and diarrhoea, may prompt the addition of over-the-counter or prescription remedies, potentially offsetting any reductions in other classes of medication.
Expanded medicare access from july
The clinical context is changing rapidly. Starting in July, obesity medications will become available at low cost for eligible Medicare beneficiaries under a federally funded demonstration programme running until December 2027. For the first time, GLP-1 medications will be broadly covered by Medicare for the treatment of obesity.
This expansion is widely expected to drive a surge in GLP-1 prescriptions among older adults. What happens after the demonstration period ends, however, is uncertain. If prices rise sharply once the programme concludes, many people may face the prospect of either paying out of pocket or stopping treatment altogether.
The risks of discontinuation
Stopping GLP-1 therapy is not a neutral event, particularly for older adults whose metabolic health may have improved markedly on treatment.
“Discontinuing can lead to worsened insulin resistance, and gaining more fat tissue than had been lost,” Chen says. “This may be dangerous, with some patients ending up in a worse situation after stopping than they were before starting.”
This raises difficult clinical and policy questions about how to ensure continuity of care once the demonstration programme concludes, and how to counsel older adults about the long-term commitment that GLP-1 therapy may represent.
The continuing role of medical reconciliation and deprescribing
The findings reinforce the importance of established tools for managing medication burden in older adults, rather than relying on a single new drug class to resolve polypharmacy.
“The tried-and-true methods for polypharmacy are medical reconciliation and rational deprescribing,” says Chen. “Many of these approaches, developed by and publicized by the National Institutes of Health-funded U.S. Deprescribing Research Network, are effective tools for geriatricians and primary care doctors.”
The researchers conclude that medication burden must remain front of mind when treating older adults, and that further research is needed to clarify how obesity medications affect health outcomes specifically in this age group.
Additional authors on the study include Ashwin Chetty, John Batsis, MD, and Kasia Lipska, MD, MHS.
Source: Yale School of Medicine
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Tirzepatide May Activate Calorie-Burning Brown Fat in Obesity, Trial Suggests
Key Takeaways:
- Findings from the TABFAT trial, presented at ENDO 2026, indicate that tirzepatide does more than curb appetite – it also appears to activate brown adipose tissue, a heat-producing fat that burns calories.
- Among premenopausal women with obesity, the proportion with PET/CT-detectable brown fat activity rose from 41.2% to 64.7% after 24 weeks of treatment, with no comparable change in the placebo group.
- Researchers also saw potential signs of white fat taking on more metabolically active “beige” characteristics, pointing towards future therapies that pair appetite control with increased energy expenditure.
Beyond appetite: a different question
For people taking tirzepatide, weight loss has so far been explained mainly by a reduced appetite and the smaller portions that follow. New research suggests the picture may be more complex. The medication appears to do more than dampen hunger – it also seems to switch on brown adipose tissue, a metabolically active fat that generates heat and consumes calories. The findings, described by the research team as a notable milestone in obesity research, were due to be presented on Monday at ENDO 2026, the Endocrine Society’s annual meeting in Chicago, Illinois.
The study set out to look past the appetite-suppressing effect that has dominated explanations of how these medications work. As lead investigator Rok Herman, M.D., of the Department of Endocrinology, Diabetes and Metabolic Diseases at University Medical Centre Ljubljana in Ljubljana, Slovenia, put it: “In the TABFAT trial, we asked a different question: beyond eating less, does tirzepatide also change how the body burns energy – specifically through brown adipose tissue, a metabolically active type of fat that produces heat and consumes calories?”
What is brown adipose tissue?
Brown adipose tissue, often referred to as brown fat, was for many years thought to disappear after infancy. Its presence in adults was only confirmed through imaging studies in the late 2000s. Unlike ordinary white fat, which mainly stores energy, brown fat burns it to produce heat. In people living with obesity this tissue is markedly suppressed, and until now moderate cold exposure has been its strongest recognised activator.
How the TABFAT trial was designed
The team led by Herman ran a randomised, placebo-controlled clinical trial in premenopausal women with obesity. To assess what was happening within the tissue itself, the researchers used cold-stimulated PET/CT imaging alongside MRI scans, measuring brown adipose tissue activity both before treatment and after 24 weeks. Using more than one imaging method allowed the team to capture different aspects of brown fat biology rather than relying on a single measure.
What the scans revealed
The results pointed to a measurable change in how the body handled energy, not simply how much participants ate. “We found that tirzepatide significantly increased brown adipose tissue activity and volume, and it also showed potential signs of converting white subcutaneous fat into more metabolically active ‘beige’ fat,” Herman said.
The shift was clear in the imaging data. Tirzepatide increased PET/CT-detectable brown adipose tissue activity from 41.2% to 64.7% of participants, while no comparable change was seen in the placebo group. The researchers were reassured that the effect showed up across the different scanning techniques used. “We were also encouraged by the consistency of the signal across other imaging modalities employed in the study that may capture different component of brown fat biology,” Herman added.
Why this matters for obesity care
The findings suggest a fuller account of how the latest anti-obesity medications work. Rather than acting on appetite alone, tirzepatide also appears to influence how much energy the body burns at the level of the tissue. “This adds a new layer to how we understand the new generation of anti-obesity medications,” Herman said. “They are not only appetite suppressants – tirzepatide also appears to modulate energy expenditure at the tissue level, opening a plausible path toward future therapies that combine appetite regulation with thermogenic activation.”
Looking ahead
Herman suggests that future research should measure, study and potentially enhance brown and beige fat activity, treating it as a specific target within a more tailored approach to obesity care. If brown fat activation can be reliably encouraged and built upon, it may complement the appetite-related effects already well documented, broadening the options available to people living with obesity.
This article summarises findings presented at ENDO 2026, the Endocrine Society’s annual meeting. Research presented at conferences may not yet have completed full peer review.
Source: Endocrine Society
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GLP-1 Medications Show No Harm to Fertility – and May Benefit Men With Obesity, New Analysis Finds
Key Takeaways:
- A new review of randomised controlled trials found that GLP-1 medications do not harm male hormones, sexual function or sperm quality after long-term use, and in some cases appear to improve them.
- In men with obesity and weight-related low testosterone, treating the underlying excess weight and poor metabolic health may naturally restore hormone levels while preserving fertility – potentially offering an alternative to testosterone replacement therapy.
- The findings are encouraging but preliminary; with only five eligible trials and varying results, the research team stresses that larger, better-designed studies are still required.
A reassuring picture for male reproductive health
Long-term use of GLP-1 medications does not harm male hormones or fertility, according to research being presented on Monday at ENDO 2026, the Endocrine Society’s annual meeting in Chicago, Illinois. The findings go further still: the research team reported that GLP-1 medications may actually raise testosterone levels and improve sperm quality in men who have obesity-related low testosterone, while simultaneously tackling the metabolic problems that sit beneath those hormonal changes.
How the study was carried out
The work was led by scientists at University Hospitals Coventry and Warwickshire and Warwick Medical School in Coventry, United Kingdom. The team searched medical databases for published randomised controlled trials, narrowing their focus to studies that compared GLP-1 medications against other treatments or a placebo in men aged 18 to 65.
Their primary interest lay in changes to testosterone and the other hormones that govern testicular function. Alongside this, they also assessed sperm quality, body weight, blood sugar, cholesterol and broader markers of metabolic health. To reduce the risk of bias, two independent reviewers checked each study, and five clinical trials ultimately met the eligibility criteria.
What the trials revealed
Across these reports, GLP-1 medications showed no negative effect on hormones, sexual function or sperm quality.
In one 24-week semaglutide study, men saw improvements in sperm shape and cholesterol levels, while their testosterone and other hormone levels remained stable. A separate 16-week liraglutide study, conducted in men with obesity and low testosterone driven by excess weight, found that participants experienced increases in testosterone and related hormones. Notably, their overall health outcomes were better than those achieved with testosterone replacement alone.
Treating the cause rather than the symptom
For the research team, the most significant implication concerns how clinicians approach low testosterone in men with obesity.
“This work supports a shift away from prescribing testosterone replacement in men with obesity and low testosterone and toward treating the underlying cause – excess weight and poor metabolic health – which can naturally restore hormone levels and preserve fertility,” said endocrinologist and team lead Pratibha Natesh, M.B.B.S., M.R.C.P., M.Res., at Warwick Medical School.
Important caveats
While the outcomes are positive, Dr Natesh was careful to temper expectations. The body of evidence remains small and the results vary between studies, so larger and better-designed trials are needed before the effects on male fertility can be fully understood.
She also cautioned that most of the reproductive benefits observed are likely to be indirect, flowing from improved metabolic health rather than from any direct action on the reproductive system. Importantly, GLP-1 medications have not been evaluated as treatments for male infertility or hypogonadism, and should not be regarded as such.
The wider takeaway
By providing clear, evidence-based information about GLP-1 weight-loss and diabetes medications, Dr Natesh hopes the research will help people make better-informed decisions about these treatments.
“Improving metabolic health can have positive effects far beyond weight alone,” she said.
Source: Endocrine Society
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