How Losing Around 80 Minutes of Sleep a Night Could Drive Weight Gain and Inactivity
Key Takeaways:
- Adults who cut their nightly sleep by about 80 minutes over six weeks gained roughly one pound (around 0.45 kg) on average and became more sedentary, Columbia University researchers found.
- Modest over six weeks, but the team estimates that sustaining this mild sleep loss for a year could cause clinically meaningful weight gain – a pattern affecting around 30% of adults.
- Related work in the same participants linked mild sleep restriction to greater insulin resistance and heart inflammation, pointing to a wider risk of type 2 diabetes and heart disease.
Why modest sleep loss deserves attention
Trimming a little sleep each night may carry more weight for your health than you might realise. Researchers at Columbia University Vagelos College of Physicians and Surgeons found that adults who shortened their nightly sleep by about 80 minutes over a six-week period gained an average of one pound and spent more of their waking hours being inactive.
The findings add to a growing body of evidence suggesting that consistently getting enough sleep may play an important role in preventing weight gain and in lowering the risk of obesity-related disease. Rather than pointing solely to diet and exercise, the results place sleep alongside them as a factor worth taking seriously.
“Our study shows that getting adequate sleep may help reduce the risk of weight gain and obesity-related conditions like heart disease and diabetes,” says Marie-Pierre St-Onge, a professor of nutritional medicine in Columbia’s Department of Medicine and Institute for Human Nutrition and the study leader. “People tend to gain weight over the course of their adulthood, and obesity is a major risk factor for heart disease. But focusing on eating a healthier diet and getting more physical activity to offset weight gain is simplistic and can be difficult to maintain.”
Looking beyond extreme sleep deprivation
Much of the earlier research connecting poor sleep with obesity has centred on severe sleep deprivation, frequently restricting people to as little as four hours of sleep a night. Those studies indicated that extreme sleep loss can heighten appetite and encourage overeating – behaviours that in turn contribute to weight gain.
The difficulty is that such severe restriction is hard for most people to sustain for more than a few days, which limits how far the results can be applied to everyday life. Very few people live with four hours of sleep for weeks at a time, so the relevance of those findings to the wider population has remained uncertain.
“These studies only show us what happens under the most extreme conditions and don’t tell us if mildly sleep-deprived people, like a lot of Americans who get 5 or 6 hours of sleep a night, will gain weight,” St-Onge says.
To reflect real-world habits more closely, the researchers set out to examine the effects of chronic, mild sleep loss – a pattern estimated to affect around 30% of adults.
Six weeks of less sleep led to measurable changes
The study involved 95 adults who typically slept between seven and eight hours each night. During one six-week phase, participants delayed their usual bedtime by 90 minutes, which shortened their nightly sleep. During a separate six-week phase, they kept to their normal sleep schedule, allowing each participant to serve as their own comparison.
Across both phases, participants wore wrist monitors that tracked sleep and physical activity. The researchers also measured body weight, waist circumference, body composition, and fasting levels of several hormones involved in regulating appetite, building a detailed picture of how the body responded to the change.
“While the one-pound weight gain observed with modest sleep curtailment is not overwhelming, it is important to remember this is occurring over just six weeks,” says Faris Zuraikat, assistant professor of nutritional medicine in Columbia’s Department of Medicine and Institute for Human Nutrition and first author of the study. “Our study was designed to mimic sleep patterns that most adults experience chronically. When extrapolated to a full year, we would expect that losing less than an hour and a half of sleep per night could result in clinically meaningful weight gain.”
Less sleep also meant more sitting
Alongside the change in weight, the researchers found that participants became less active during the sleep-restriction phase. On average, sedentary time rose by 17 minutes per day. Among men and postmenopausal women, inactivity climbed by nearly 30 minutes each day.
Notably, this increase in sitting held up even after accounting for the extra waking hours that come with shorter sleep – so the added inactivity was not simply a matter of being awake for longer.
“Even when we accounted for the fact that they were awake longer when sleep was shortened, participants spent more time being inactive than when they got adequate sleep,” Zuraikat says. “This is notable, as people who are more sedentary have elevated risk for chronic diseases.”
Earlier research suggests broader health effects
The same group of participants has featured in several related studies, which together suggest that the consequences of mild sleep loss may extend well beyond weight. In one earlier investigation, women with increased cardiometabolic risk who reduced their sleep by about 80 minutes each night for six weeks developed greater insulin resistance – an important risk factor for type 2 diabetes. The effect was particularly pronounced in postmenopausal women.
A separate study found that men and women with an elevated risk of heart disease developed an influx of inflammatory cells in the heart after undergoing mild sleep restriction, hinting at a possible mechanism linking short sleep to cardiovascular harm.
“Though more research is needed to further understand how sleep restriction leads to weight gain, all of our findings suggest that insufficient sleep increases the risk of obesity-related conditions like type 2 diabetes and heart disease,” St-Onge says.
“Now we need to understand the health effects of improving sleep in those who fail to get adequate sleep on a regular basis.”
About the study
The study, titled “Skimping on Sleep and Its Impact on Body Weight and Composition: A Pooled Analysis of Randomized Trials,” was published on 6 July in Annals of Internal Medicine.
The authors are Faris Zuraikat, Samantha Scaccia, Justin Cochran, Bin Cheng, Keith Diaz, Seth Creasy (University of Colorado), Brooke Aggarwal, Sanja Jelic, and Marie-Pierre St-Onge. The authors report no conflicts of interest.
Read More
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.
CCH insights:
These are very encouraging results for the use of time-restricted eating (TRE) as a strategy for weight loss maintenance. It would be good to now see research into the use of TRE as a tool to prevent weight regain after cessation of GLP-1 therapy. If TRE is adopted during GLP-1RA treatment, and continued after stopping the medication, could it help maintain weight loss and cardiometabolic gains?
Helping patients hold on to their gains — during treatment and in the months after it ends — is exactly the terrain of our two-hour CPD course GLP-1RAs in Practice: Supporting Patients During Treatment, which covers nutrition, monitoring and preparing patients for life after treatment for any clinician managing the full arc of GLP-1RA care.
Read More
Year-Long Trial Finds Rapid Weight Loss Outperforms a Gradual Approach, Overturning a Long-Held Assumption
Key Takeaways:
- In a 52-week randomised trial, adults living with obesity who followed a rapid weight loss programme lost significantly more weight at one year than those on a gradual programme (14.4% versus 10.5% of total body weight), and the gap held throughout the study.
- Rapid weight loss was not associated with greater weight regain, directly contradicting the widespread belief that losing weight slowly is necessary to keep it off.
- A larger share of people in the rapid weight loss group reached clinically meaningful BMI and waist-to-height targets linked to a lower 10-year risk of obesity-related conditions.
A long-held belief comes under scrutiny
New research presented at the European Congress on Obesity (ECO 2026) in Istanbul, Turkey, indicates that rapid weight loss (RWL) is considerably more effective than gradual weight loss (GWL), both in the amount of weight people lose and in how well that loss is sustained at one year.
For years, conventional thinking has held that rapid weight loss is unhealthy and that shedding weight very quickly raises the chance of regaining it. Yet these concerns rest largely on observational data, historical assumptions, or small studies with methodological limitations. The scientific evidence directly supporting them is limited and inconsistent, and high-quality randomised controlled trial evidence remains relatively sparse.
The study was led by Dr Line Kristin Johnson of the Department of Endocrinology, Obesity and Nutrition at Vestfold Hospital Trust in Tønsberg, Norway, together with colleagues. The centre is a collaborating centre with the European Association for the Study of Obesity (EASO-COM-Centre); EASO leads obesity advocacy and education across Europe and organises ECO.
Setting the treatment targets
A recent large, population-based cohort study concluded that, after weight loss, a body-mass index (BMI) of 27 kg/m² or below and a waist-to-height ratio (WHtR) of 0.53 or below may represent clinically meaningful treatment targets for lowering the 10-year risk of obesity-related complications, namely type 2 diabetes, hypertension, atherosclerotic cardiovascular disease, and hip and knee osteoarthritis.
In this new study, the researchers set out to compare how effectively a rapid weight loss programme and a gradual weight loss programme helped people reach those targets.
How the trial was designed
The 52-week, investigator-initiated, randomised clinical trial was run as a collaboration between the Department of Endocrinology, Obesity and Nutrition at Vestfold Hospital Trust and Roede AS, one of Norway’s leading and most established providers of commercial weight loss programmes.
In total, 284 adults living with obesity (BMI of 30 or above), of whom 257 (90%) were women, were randomised on a one-to-one basis to one of two 16-week, food-based programmes. The rapid weight loss programme reduced energy intake in stages: under 1,000 kcal per day in weeks 1 to 8, under 1,300 kcal per day in weeks 9 to 12, and under 1,500 kcal per day in weeks 13 to 16. The gradual weight loss programme set intake at 800 to 1,000 kcal per day below each participant’s estimated total energy expenditure, with a mean self-reported intake in this group of roughly 1,400 kcal per day.
Estimated energy expenditure was calculated from each participant’s estimated resting energy expenditure and then adjusted according to whether they had low, medium, or high physical activity.
The food composition in both programmes followed current Norwegian dietary recommendations from the Norwegian Directorate of Health. Core advice included eating healthy foods such as vegetables, fruits, whole grains, low-fat dairy products, fish, eggs, lean meat, and other protein-rich foods, while limiting saturated fats and added sugars.
Maintaining the results
After the initial weight loss phase, participants in both groups moved into an identical 36-week weight-regain prevention programme.
Throughout the study, the interventions included weekly in-person group sessions from week 1 to week 16. After that, in-person group meetings took place every 14 days for the first three months, followed by monthly meetings or individual contact via webinars, video, or telephone for the remaining five months.
In these sessions, participants were advised to raise their daily energy intake by 100 to 300 kcal during the first month, until their weight stabilised. From then on, daily intake was adjusted as needed in response to any weight changes across the eight-month maintenance phase. Participants could decide for themselves whether to maintain their weight or aim for further loss, and the majority chose to keep losing weight after the initial 16-week period.
What the trial found
Of the 284 participants, 142 were randomised to the rapid weight loss programme and 142 to the gradual weight loss programme. At baseline, the rapid weight loss group had a mean age of 48.5 years, body weight of 102.4 kg, height of 169 cm, BMI of 35.8 kg/m², waist circumference of 112.5 cm, and WHtR of 0.67. The corresponding figures in the gradual weight loss group were 47.7 years, 103.0 kg, 168 cm, 36.5 kg/m², 112.8 cm, and 0.67.
The primary outcome was one-year percentage total body weight loss (%TBWL). The proportion of participants reaching a BMI of 27 kg/m² or below, or a WHtR of 0.53 or below, after one year were exploratory outcomes.
During the first 16 weeks, the rapid weight loss group lost significantly more weight than the gradual weight loss group, with a mean %TBWL of -12.9% compared with -8.1%, a between-group difference of -4.8%.
At one year, that significant difference was maintained: the mean %TBWL was -14.4% in the rapid weight loss group and -10.5% in the gradual weight loss group, a between-group difference of -3.9 percentage points.
The share of participants achieving a BMI of 27 kg/m² or below was significantly higher in the rapid weight loss group than in the gradual weight loss group at both 16 weeks (13.8% versus 0.8%) and one year (28.3% versus 9.7%). A higher proportion also reached a WHtR of 0.53 or below in the rapid weight loss group, both at 16 weeks (24.2% versus 8.9%) and at one year (33.0% versus 18.4%).
What the researchers say
The authors conclude, “Among adults with obesity, participation in a structured rapid weight loss program resulted in significantly greater weight loss at one year, and higher rates of achieving clinically meaningful BMI and WHtR targets compared with a gradual weight loss approach.
“These findings indicate that, when provided within a controlled and professionally supervised setting, rapid weight loss may represent a more effective method than gradual weight loss for reaching key body weight targets associated with reduced obesity-related health risks.”
Dr Johnson adds, “Our results clearly challenge the prevailing belief that slow and steady gradual weight loss is necessary to prevent weight regain and reduce obesity-related complications.
“By contrast, we show that rapid weight loss is not associated with weight regain, and, more importantly, that a larger proportion of participants undergoing rapid weight loss – compared with gradual weight loss – achieved clinically meaningful treatment targets for reducing the 10-year risk of type 2 diabetes, hypertension, atherosclerotic cardiovascular disease, and hip/knee osteoarthritis.
“These findings are particularly relevant given the urgent need for effective weight-loss and weight-maintenance strategies. As many individuals with obesity cannot access or afford medical or surgical treatments, our results support the potential of effective, commercially available weight-reduction programs to help reduce the growing burden on public health care systems.”
Why it matters
With obesity placing a rising strain on health systems, and with medical and surgical treatments out of reach for many, the trial points to professionally supervised commercial programmes as a potential route to meaningful, lasting results. Its central message reframes a long-standing assumption: under proper supervision, losing weight quickly did not undermine maintenance, and it helped more people reach the targets tied to lower long-term health risks.
CCH insights:
These are impressive results for a diet and lifestyle intervention, with both groups achieving greater than 10% total body weight loss over a period of a year. However, participants received fairly intensive support throughout the entire year of the trial. The important thing is what happens in the next 12 months, after the intervention has stopped – are they able to sustain behavioural changes and weight loss without the support from the programme?
Source: Medical Xpress
Read More
Hong Kong Unveils First Territory-Wide Weight Management Strategy to Address Rising Obesity Rates
Key Takeaways:
- Hong Kong has launched its first comprehensive three-year Action Plan on Weight Management, introduced on World Obesity Day (4 March) in response to data showing that more than half of the city’s adults are living with overweight or obesity.
- The strategy is built around five pillars and 15 specific objectives, including improved health education, strengthened healthcare services, and environmental changes that support healthier lifestyles.
- Officials acknowledge that low awareness and misperceptions about body weight remain major barriers, with many individuals who are overweight believing their weight is “just right”.
Hong Kong launches its first comprehensive weight management plan
Hong Kong has introduced its first territory-wide action plan aimed at improving weight management across the population, marking a significant step in the city’s efforts to address rising levels of overweight and obesity.
The initiative was officially launched on World Obesity Day, 4 March, and will run for three years. It follows findings from the Department of Health’s Population Health Survey conducted between 2020 and 2022, which revealed that more than half of Hong Kong’s adult population are living with either overweight or obesity.
Officials have positioned the plan as part of broader international and national efforts to address obesity. The strategy contributes to China’s national Weight Management Year initiative and aligns with the World Health Organization’s global framework aimed at reducing obesity worldwide.
The new plan aims not only to raise awareness of weight management but also to create conditions that make healthier choices easier for people across the territory.
A framework built around five strategic pillars
The action plan is organised around five core pillars, each designed to address different aspects of weight management across society.
These pillars include:
- Strengthening health education and promotion
- Creating a supportive social environment
- Enhancing health service delivery
- Adopting a life-course approach to health promotion
- Continuously monitoring population weight trends
Together, these pillars translate into 15 concrete objectives that government departments will pursue during the programme’s three-year implementation period.
The timeline of the plan is also structured in stages. 2026 will focus primarily on raising public awareness, helping people better understand healthy weight and lifestyle behaviours. The second year will concentrate on encouraging positive behavioural change, while the final year will emphasise long-term maintenance, with the goal of embedding healthier habits into everyday life.
Public initiatives begin with a city-wide walking challenge
The first public initiative under the strategy will begin on 21 March, when authorities launch a “10,000 Steps a Day” walking challenge.
The programme will be integrated into the eHealth mobile application’s e+Life platform, allowing participants to track their daily activity digitally. The launch will be marked by a ceremony and public carnival at the West Kowloon Cultural District, intended to encourage participation and raise awareness about physical activity.
Alongside this campaign, the action plan outlines several longer-term measures aimed at promoting healthier lifestyles across the city.
These include:
- Installing weight measurement devices in public housing estates and schools
- Integrating weight management education into school curricula
- Designing pedestrian-friendly urban environments that encourage walking and other forms of physical activity
By combining digital tools, education, and environmental changes, officials hope to create a more supportive ecosystem for healthier behaviours.
A life-course approach to health promotion
According to public health officials, the plan adopts a life-course approach, addressing health and weight management from the earliest stages of life through to older adulthood.
Dr Edwin Tsui, controller of the Centre for Health Protection, explained that the strategy is intended to cover the entire lifespan.
He said the plan takes “a systematic approach covering the full lifespan, from prenatal nutrition to maintaining function in old age.”
Tsui also emphasised the role of primary healthcare as a central component of the initiative, noting that healthcare services will act as the gatekeeper of public health within the strategy.
The plan also encourages collaboration between Chinese medicine and Western medicine practitioners, reflecting Hong Kong’s mixed healthcare landscape. At the same time, authorities intend to use the eHealth digital platform to help residents track and manage their personal health information.
Low awareness and misperceptions present major challenges
Despite the ambitious scope of the initiative, health officials acknowledge that significant barriers remain.
One of the most notable challenges is limited awareness about healthy weight and weight management among the public.
Dr Anne Chee, head of the Non-Communicable Disease Branch at the Department of Health, highlighted this issue during a radio programme. She explained that many individuals living with overweight may not recognise it as a health concern.
Among people who are overweight, she said two-thirds believe their weight is “just right” or even “too thin.”
Chee also noted that many individuals have taken no action to manage their weight over the past year, reflecting gaps in public understanding of healthy weight management.
She further emphasised that some people may not know how to calculate their body mass index, pointing to broader deficiencies in knowledge related to weight and health.
Sustaining behaviour change may prove difficult
Experts outside government have also raised concerns about the challenge of maintaining behavioural change over time.
Sports scientist Professor Lobo Louie from the Education University of Hong Kong warned that while awareness campaigns can be effective, they do not always translate into lasting lifestyle changes.
Louie pointed to the gap between initial engagement and long-term commitment, noting that maintaining motivation may prove difficult for many individuals.
This highlights a broader challenge faced by public health initiatives worldwide – transforming awareness into sustained behaviour change.
Cross-government collaboration to support healthier lifestyles
The action plan is designed as a cross-government initiative, bringing together multiple public agencies.
Departments involved include those responsible for:
- Health
- Education
- Leisure and cultural services
- Urban planning
A cross-departmental working group established in October is coordinating these efforts. The group aims to strengthen collaboration not only within government but also with businesses, academic institutions, and community organisations.
Officials hope that this multi-sector approach will create broader societal support for healthier lifestyles.
A voluntary strategy with long-term ambitions
For the moment, the programme relies largely on voluntary participation and public education, rather than regulatory measures.
Whether these measures will be sufficient to reverse current trends remains uncertain. Officials recognise that individual willpower or clinical care alone cannot solve the obesity challenge.
Instead, they emphasise that the wider social and physical environment must also support healthier choices, making it easier for people to adopt and maintain healthy behaviours.Further information about the strategy and related initiatives is available on the Department of Health’s Change4Health website.
CCH insight:
We wish the authorities and people of Hong Kong the best of luck with this programme, but evidence from other countries suggest it is highly unlikely to make a significant reduction in the prevalence of obesity. We know that obesity results from genetic and biological factors driving overeating, made possible by an environment which encourages over-consumption of food. The programme is not attempting to change the population’s biology (by increasing access to anti-obesity medications, for example), nor to restrict the availability of obesogenic foods, so it is unlikely to lead to the kind of changes in behaviour it is aiming for.
Read More
New Cochrane Review Finds Intermittent Fasting Offers No Clear Weight Loss Advantage
Key Takeaways:
- A major Cochrane review found intermittent fasting did not lead to clinically meaningful weight loss compared with standard dietary advice or no structured diet.
- Evidence on safety and long-term outcomes remains limited due to small trials, inconsistent reporting, and short follow-up periods.
- Experts caution against overinterpreting social media claims and emphasise the need for individualised, long-term approaches to weight management.
Intermittent fasting under scrutiny
Intermittent fasting has become one of the most widely promoted dietary strategies for weight loss, often presented as a superior alternative to conventional calorie reduction. However, a new Cochrane review suggests that these claims may not be supported by robust evidence.
According to the review, intermittent fasting does not appear to deliver greater weight loss than standard dietary advice or even no specific diet plan. The findings challenge the widespread perception that structured fasting schedules offer a unique or clinically meaningful advantage for people who are overweight or living with obesity.
Obesity remains a global public health challenge
Obesity continues to represent a major public health concern worldwide and is now among the leading causes of death in high-income countries. Data from the World Health Organization show that global adult obesity rates have more than tripled since 1975. By 2022, an estimated 2.5 billion adults were classified as overweight, including around 890 million adults living with obesity.
Against this backdrop, intermittent fasting has gained substantial attention. Eating patterns such as alternate-day fasting, periodic fasting, and time-restricted feeding are widely promoted across social media platforms, often accompanied by claims of rapid weight loss and metabolic benefits.
What the review examined
To assess whether intermittent fasting truly offers an advantage, researchers analysed 22 randomised clinical trials involving 1,995 adults across North America, Europe, China, Australia, and South America. The studies evaluated a range of fasting approaches, including alternate-day fasting, periodic fasting, and time-restricted feeding. Most trials followed participants for up to one year.
When outcomes were compared with those of traditional dietary advice or no dietary intervention, intermittent fasting did not result in a clinically meaningful difference in weight loss. In practical terms, fasting-based approaches did not outperform more conventional strategies.
Limited evidence on safety and long-term outcomes
The review also highlighted substantial limitations in the available evidence. Reporting of side effects varied widely between studies, and many trials were relatively small. Inconsistent data collection made it difficult to draw firm conclusions about safety or potential long-term effects.
As a result, the overall certainty of the evidence was judged to be limited.
“Intermittent fasting just doesn’t seem to work for overweight or obese adults trying to lose weight,” said Luis Garegnani, lead author of the review from the Universidad Hospital Italiano de Buenos Aires Cochrane Associate Centre.
Social media enthusiasm outpaces the evidence
Garegnani also warned against the level of enthusiasm surrounding intermittent fasting online. “Intermittent fasting may be a reasonable option for some people, but the current evidence doesn’t justify the enthusiasm we see on social media.”
A further concern is the lack of long-term research. Few studies have examined outcomes beyond relatively short trial periods. “Obesity is a chronic condition. Short-term trials make it difficult to guide long-term decision-making for patients and clinicians,” Garegnani added.
Generalisability remains uncertain
Most of the studies included in the review primarily involved white participants living in high-income countries. Given that obesity prevalence is rising rapidly in low and middle-income countries, the findings may not fully reflect outcomes in more diverse global populations.
The authors note that responses to intermittent fasting could vary depending on sex, age, ethnic background, underlying health conditions, or existing eating behaviours and eating disorders.
Implications for clinical practice
Given the current state of evidence, the review’s authors advise caution when recommending intermittent fasting as a weight loss strategy.
“With the current evidence available, it’s hard to make a general recommendation,” said Eva Madrid, senior author from the Cochrane Evidence Synthesis Unit Iberoamerica. “Doctors will need to take a case-by-case approach when advising an overweight adult on losing weight.”
Overall, the findings reinforce the need for personalised, sustainable approaches to weight management rather than reliance on highly promoted dietary trends.
Read More