In the past few years there has been a lot of criticism of the BMI system due to its inability to accurately capture body fat percentage or distribution, in order to correctly categorise weight status based on adiposity explains Professor Marwan El Ghoch, of the Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.  He adds that, despite these concerns, BMI as a weight classification system continues to be used in the general population in primary healthcare (i.e. general practitioners) and non-clinical (i.e. policy and health insurance) settings.

In this new study, Professor El Ghoch and researchers from the University of Verona in Italy and Beirut University in Lebanon set out to determine the validity of the BMI classification system, specifically regarding its ability to identify correctly those with overweight and obesity, in a sample of the general population who had all had their body fat measured using DXA. With DXA, the person’s age and body fat percentage is used to decide their weight status category according to their level of adiposity.*

The study included 1351 adults of mixed gender aged between 18 and 98 years (60% female) all of whom were referred to the Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy. All the participants in this study where White Caucasian (due to BMI variations in different ethnicities).

According to the WHO BMI system, among these participants there were 19 (1.4%) underweight individuals (BMI under 18.5), 787 (58.3%) normal weight (BMI 18.5-25), 354 (26.2%) with overweight (BMI 25-30), and 191 (14.1%) with obesity (BMI over 30). The overall prevalence of approximately 41% for overweight and obesity combined is consistent with the local population in the Veneto region of Italy. Participants were then re-categorised according to adiposity based on body fat percentage (BF%) measured by DXA.

DXA revealed that more than one third (34%) of those with obesity defined by BMI had been misclassified and should be in the overweight category. For those with an overweight BMI, DXA showed that more than half – 53% – had been misclassified – three quarters of those misclassified fall into the normal weight category, while the other quarter should have been classified as having obesity.

BMI and DXA had better agreement when considering those with a normal weight BMI (18.5 to 25), with DXA agreeing in 78% of cases. But 22% of those with normal weight were given a different category with DXA (9.7% underweight, 11.4% overweight and 0.8% obesity). Finally, despite the small absolute numbers, the biggest BMI-DXA disagreement was found in the underweight group – two thirds (13 of 19; 68.4%) in the underweight category defined by BMI (under 18.5) were in the wrong category when analysed by DXA – and should have been classified as having normal weight.

With all the correct and misclassifications combined, the DXA analysis found that the prevalence of overweight and obesity across the cohort was at around 37% overall (23.4% overweight, and 13.2% obesity, compared to 26.2% and 14.1% with BMI).

Professor El Ghoch, who led the study, says: “Our main finding highlights the fact that a large proportion of individuals, exceeding one-third of adults among the Italian general population, is misclassified and placed in an incorrect weight status category, when relying on the traditional WHO BMI classification resulting in an overestimation of the prevalence of underweight, overweight, and obesity when compared to the classification based on body fat percentage as measured by the gold standard technique of dual-energy X-ray absorptiometry (DXA).”

Study co-author, Professor Chiara Milanese, of the University of Verona, adds: “Another key finding of our study is that, even though both systems identify a similar overall prevalence of overweight and obesity,  we are talking in some cases about different people – or in other words the individuals identified by DXA are not all the same as those from BMI classification. This is due to the disagreement between WHO BMI and DXA-derived BF% classification systems in determining weight status in the general population among body weight ranges and age groups of both genders.”

Accordingly, the authors conclude: “Public health guidelines in Italy need to be revised to consider combining direct body composition or their surrogate measures such as skinfold measurement or body circumference – such as the waist-to-height ratio – with BMI while assessing weight status in the general population. We believe a similar level of misclassification can be expected in White Caucasian populations in other countries in Europe and Worldwide. However, to confirm this, and if a similar effect exists in other ethnicities, future research should extend the aim of our analysis to other countries across Europe and globally, as well as seeing if such misclassification occurs in people of other ethnicities.”

Professor Marwan El Ghoch, University of Modena and Reggio Emilia, Modena, Italy. T) +39 0592055371 E) m.elghoch@unimore.it

Tony Kirby in the ECO Media Centre. T) +44 7834 385827 E) tony.kirby@tonykirby.com

The authors confirm no conflicts of interest.

This press release is based on oral presentation 0360 at the European Congress on Obesity (ECO) in Istanbul, Turkey, 12-15 May. The material has been peer reviewed by the congress selection committee. The full paper has been published in the journal Nutrients. As such, the full paper is provided in place of the abstract.

The following thresholds are used in DXA – body fat values to give weight status:

For males:

18–39 years BF% < 8% (underweight); ≥8% (normal weight); ≥21% (overweight); ≥26% (obesity); 40–59 years BF% < 11% (underweight); ≥11% (normal weight); ≥23% (overweight); ≥29% (obesity) 60–98 years BF% < 13% (underweight); ≥13% (normal weight); ≥25% (overweight); ≥31% (obesity).

For females:

18–39 years BF% < 21% (underweight); ≥21% (normal weight); ≥33% (overweight); ≥39% (obesity); 40–59 years BF% < 23% (underweight); ≥23% (normal weight); ≥35% (overweight); ≥41% (obesity); 60–98 years BF% < 26% (underweight); ≥26% (normal weight); ≥36% (overweight); ≥41% (obesity).

For full paper, click here

The study, published in the journal Health Psychology, found that adults who followed more routine eating patterns, such as repeating the same meals and keeping calorie intake steady over time, lost more weight during a 12-week behavioral weight loss program than those who ate a more varied diet.

“Maintaining a healthy diet in today’s food environment requires constant effort and self-control,” said lead author Charlotte Hagerman, PhD, of the Oregon Research Institute. “Creating routines around eating may reduce that burden and make healthy choices feel more automatic.”

Researchers analyzed detailed, real-time food logs from 112 overweight or obese adults who were enrolled in a structured behavioral weight loss program. Participants were asked to track everything they ate each day using a mobile app, along with daily weigh-ins using a wireless scale. To ensure the data reflected consistent habits, researchers focused on the first 12 weeks of the program — a period when participants are typically most engaged and accurate in tracking their food intake.

The researchers then measured how “routinized” each person’s diet was in two ways. First, they looked at caloric stability, or how much a person’s daily calorie intake fluctuated from day to day and between weekdays and weekends. Second, they examined dietary repetition, tracking how often participants logged the same meals and snacks over time, rather than constantly choosing new foods.

In the end, those who repeated many of the same foods rather than eating a wide variety lost an average of 5.9% of their body weight, compared with 4.3% among those whose diets were more varied. The study also found that greater day-to-day calorie consistency was linked to better results. For every 100-calorie increase in daily fluctuation, weight loss decreased by about 0.6% over the study period.

The findings suggest that simplifying food choices, such as creating a rotation of go-to meals and maintaining a steady calorie intake, may help people build sustainable habits in a challenging food environment. However, the researchers caution that the study shows a correlation, not cause and effect, and that factors like motivation or self-discipline may also play a role.

The authors also acknowledge that previous research has linked dietary variety with better health status. However, these studies have mostly focused on dietary variety within healthy food groups, like fruits and vegetables. “If we lived in a healthier food environment, we might encourage people to have as much variety in their diet as possible,” Hagerman said. “However, our modern food environment is too problematic. Instead, people may do best with a more repetitive diet that helps them consistently make healthier choices, even if they might sacrifice some nutritional variety.”

One unexpected finding of the study was that participants who logged higher calorie totals on weekends compared with weekdays also lost more weight. Hagerman said this most likely reflects stronger tracking habits rather than higher food intake, since people often are not as consistent with their tracking on weekends.

Still, says Hagerman, the takeaway is straightforward: when it comes to weight loss, consistency may matter more than variety.

Article: “Do Routinized Eating Behaviors Support Weight Loss? An Examination of Food Logs from Behavioral Weight Loss Participants,” by Charlotte Hagerman, PhD, Oregon Research Institute; Asher E. Hong, B.S., Drexel University; Nicole T. Crane, PhD, Drexel University; Meghan L. Butryn, PhD, Drexel University; Evan M. Forman, PhD, Drexel University. Health Psychology, published online March 26, 2026.

Contact: Charlotte Hagerman, PhD, can be reached at chagerman@ori.org.

The American Psychological Association, in Washington, D.C., is the largest scientific and professional organization representing psychology in the United States. APA’s membership includes 190,000 researchers, educators, clinicians, consultants and students. Through its divisions in 54 subfields of psychology and affiliations with 60 state, territorial and Canadian provincial associations, APA works to advance the creation, communication and application of psychological knowledge to benefit society and improve lives.

The research, published in the Journal of Medical Internet Research, established a significant and consistent association between Problematic Smartphone Use (PSU) – whereby an individual becomes behaviorally or psychologically reliant on their smartphone – and eating disorder symptom severity. Researchers argue this highlights the need for early intervention strategies specific to excessive phone use for young people displaying eating disorder symptoms.

While there has been research conducted into the negative impact that problematic internet usage, exposure to social media, and harmful online content can have on body image and body dysphoria in both clinical and non-clinical populations, none have specifically examined PSU.

Researchers identified 35 studies in which to include in this systematic review. The studies were from across the globe and provided researchers with a sample size of 52,584 participants with an average age of 17.

Their analysis of the data found that higher daily smartphone use was also related to greater food addiction symptoms, broader disordered eating behaviours like uncontrolled eating or emotional overeating, and body dissatisfaction in people with no diagnosis of an eating disorder. The association was particularly strong in those who use their phones for more than seven hours a day.

Ben Carter, Professor of Medical Statistics at King’s IoPPN and the study’s senior author said, “Smartphones have become ubiquitous in our everyday lives. It is apparent from our study that, even for people without a diagnosis of an eating disorder, the overuse of a smartphone is associated with poor body satisfaction and altered eating behaviours, and is a potential source of distress”

Dr Johanna Keeler, a Visiting Lecturer at King’s IoPPN and the study’s first author said, “Adolescence is a key stage of development as individuals evolve their sense of self by observing others. While smartphones might present an easy way for this to happen, being consistently exposed to idealised images can lead them to compare their own appearance with these “standards”, leading to poor self-esteem and appearance dissatisfaction – both risk factors for the development of an eating disorder.”

For more information, please contact Patrick O’Brien (Media Manager) on +44 020 7848 5377.

Problematic smartphone use and smartphone screen time are associated with eating disorder psychopathology in non-clinical samples: a systematic review (DOI )(Keeler, Carter et al) was published in the Journal of Internet Medical Research.

1. “Problematic Smartphone Use” is not “smartphone addiction” and should not be used interchangeably. While smartphone users can demonstrate addictive behaviours, significantly more research is required before the “addiction” moniker can be applied.

About King’s College London and the Institute of Psychiatry, Psychology & Neuroscience

King’s College London is amongst the top 35 universities in the world and 5th best in the UK (QS World University Rankings 2026), and one of England’s oldest and most prestigious universities. With an outstanding reputation for world-class teaching and cutting-edge research, King’s maintained its sixth position for ‘research power’ in the UK (2021 Research Excellence Framework).

King’s has more than 42,000 students (including more than 12,800 postgraduates) from some 190 countries worldwide, and 8,500 staff.

For nearly 200 years, King’s students and staff have used their knowledge and insight to make a positive impact on people, society and the planet. Focused on delivering positive change at home in London, across the UK and around the world, King’s is building on its history of addressing the world’s most urgent challenges head on to accelerate progress, make discoveries and pioneer innovation. Visit the website to find out more about Vision 2029, which sets out bold ambitions for the future of King’s as we look towards our 200th anniversary. World-changing ideas. Life-changing impact: kcl.ac.uk/news

In a large, randomized trial, researchers at Mass General Brigham have found that high-dose vitamin D3 did not reduce COVID-19 infection severity, but may impact long COVID outcomes. Results of the study are published in The Journal of Nutrition.

“There’s been tremendous interest in whether vitamin D supplements can be of benefit in COVID, and this is one of the largest and most rigorous randomized trials on the subject,” said senior author JoAnn Manson, MD, DrPH, of the Mass General Brigham Department of Medicine. “While we didn’t find that high-dose vitamin D reduced COVID severity or hospitalizations, we observed a promising signal for long COVID that merits additional research.”

Vitamin D has been hypothesized to boost immune health, but clinical evidence in the context of COVID-19 has been mixed. The Vitamin D for COVID-19 (VIVID) Trial aimed to provide clarity by rigorously evaluating high-dose vitamin D3 supplementation among newly diagnosed COVID-19 patients and their household contacts. Across the United States and Mongolia, 1,747 adults who had recently tested positive for COVID-19 and 277 household contacts were randomized to receive either daily vitamin D3 (9,600 IU/day for two days followed by 3,200 IU/day) or daily placebo for four weeks. The U.S. trial was conducted from December 2020 to September 2022 while the Mongolia trial ran from September 2021 to April 2022. The median time between the participants’ positive COVID-19 tests and the initiation of vitamin D supplementation or placebo was three days.

Alongside Manson, lead authors Davaasambuu Ganmaa, Kaitlyn Cook and team used stratified randomization and statistical weighting to ensure factors that can affect COVID-19 outcomes (including age, sex, body mass index, race/ethnicity and COVID-19 vaccination status) were balanced between the two groups.

The rate of healthcare utilization (including hospitalizations, in-person or virtual clinic visits, and emergency visits) or death did not differ between the vitamin D and placebo groups over a four-week period. Similarly, no significant differences were found in symptom severity. Taking high-dose vitamin D also didn’t reduce the rate at which household contacts contracted COVID-19.

However, an analysis of the participants who adhered to the vitamin D regimen demonstrated a signal that they were less likely to experience long COVID symptoms at eight weeks than those who took placebo pills. In the vitamin D group, 21% reported at least one persistent symptom, compared to 25% in the placebo group, a difference of borderline statistical significance.

“Long COVID, which can include symptoms of fatigue, shortness of breath, brain fog, other cognitive challenges and more, continues to significantly impact people’s lives,” said Manson. “We hope to conduct further research in larger populations on whether long-term vitamin D supplementation reduces the risks and severity of long COVID.”

Authorship: In addition to Manson and Ganmaa, Mass General Brigham authors include Allison Clar, Michael Rueschman, Aditi Hazra, Howard D. Sesso, Valerie E. Stone, Patricia Copeland and Georgina Friedenberg. Additional authors include Cook, Polyna Khudyakov, Dorjbal Enkhjargal, Tsolmon Bilegtsaikhan, Kenneth H. Mayer, Raji Balasubramanian, Douglas C. Smith, Quanhong Lei, Todd Lee, Emily G. McDonald, Tserenkhuu Enkhtsetseg, Erdenebaatar Sumiya, Yansanjav Narankhuu, Myagmarsuren Erdenetuya, Dalkh Tserendagva, Rikard Landberg, Niclas Roxhed and Susanne Rautiainen.

Disclosures: Roxhed is a founder and shareholder of Capitainer AB, a company commercializing the blood collection devices used in this study. All other authors declare no conflicts of interests.

Funding: The study received anonymous foundation support and philanthropic support from Jon Sabes of Minneapolis, Minn. The authors also acknowledge support from the Tishcon Corporation, which donated the vitamin D and placebo study capsules; Takeda; and Capitainer cards. The authors have not declared a specific grant for this research from any funding agency in the public, commercial or nonprofit sectors.

Paper cited: Ganmaa, D., et al. “A Randomized Trial of Vitamin D Supplementation and COVID-19 Clinical Outcomes and Long COVID: The VIVID Trial.” The Journal of Nutrition. DOI: 10.1016/j.tjnut.2026.101398

The risk is almost 5 times higher with Wegovy than it is with Ozempic, and 3 times greater in men than it is in women, the analysis indicates.

Ischaemic optic neuropathy, or ION for short, is caused by inadequate/interrupted blood flow to the optic nerve, resulting in sudden vision loss in one or both eyes.

Although rare, ION has recently been linked to GLP-1 receptor agonists, particularly semaglutide, marketed as Wegovy, Ozempic, and Rybelsus, and variously used to treat obesity, diabetes, and to reduce cardiovascular disease risk, explain the researchers. 

To pinpoint whether the risks of ION might be associated with particular drugs, the researchers analysed alerts of unintentional and harmful side effects associated with medicines submitted to the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) between December 2017 and December 2024.

The researchers focused on ION associated with up to 2 mg of weekly injectable Ozempic for type 2 diabetes; up to 2.4 mg of weekly injectable Wegovy for obesity—the highest approved dose–and a daily tablet of Rybelsus for type 2 diabetes.  

They also included a once weekly injection of tirzepatide, a dual GLP-1/GIP agonist for the treatment of obesity and diabetes, which was analysed as a combined category and by indication: Mounjaro (for type 2 diabetes); Zepbound (for obesity).

Out of 30,668,520 unintentional and harmful side effect reports, 31,774 involved semaglutide; recipients had an average age of 56, and over half (54%) were female.

Of these reports, 3070 were attributed to Wegovy, originating from 6 countries in 3 continents, and 20,608 to Ozempic, originating from 11 countries in 4 continents.

Ozempic generated about 7 times more reports than Wegovy owing to its earlier approval in 2017; Wegovy was launched in 2021.

Yet despite this difference in volume, Wegovy was most strongly associated with ION (28 reports; higher odds of nearly 75), exceeding Ozempic (47 reports; higher odds of nearly 19) and generic forms of semaglutide (85 reports; higher odds of 21).

ION wasn’t reported in association with Rybelsus. And there was no signal—possible causal association between a medicine and an unintended side effect—with the comparator drugs.

When stratified by sex, the highest signal was for Wegovy in men (116 greater odds) and for Ozempic in women (nearly 27 greater odds).

And further analysis indicated that the odds of ION were nearly 5 times higher with Wegovy than with Ozempic, and more than 3 times higher in men than in women.

Injectables are faster acting than tablets, and differences in route, dose, and indication “may influence prescribing patterns and safety signals, with high-dose Wegovy probably driving the stronger association by predisposing to optic nerve hypoperfusion [low blood supply] through intravascular volume contraction, hypotension [low blood pressure] with nocturnal dips and autonomic instability, although no direct clinical link has been established,” point out the researchers.

“In contrast, the limited absorption and slower uptake of Rybelsus probably explain the absence of a detectable signal,” they add.

Media attention may have influenced reporting for Wegovy, they suggest, emphasising that the FDA reporting system precluded the ability to determine true incidence or assess whether reports clustered following regulatory recognition. And there was no information on co-existing conditions or disease severity either.

Nevertheless, “This study provides the first evidence of a formulation-and dose-dependent ION risk, with the strongest association observed for Wegovy,” write the researchers, concluding: “These findings highlight a potential dose-dependent safety concern that warrants urgent prospective evaluation to guide prescribing and regulatory policy.”

The authors of a linked commentary agree. “These findings add to an emerging body of growing literature reporting ocular complications with [anti-obesity medications] which warrants further scrutiny and urgent clarification for ophthalmologists,” they write.

The use of these drugs is set to grow, they suggest, highlighting that: “The UK has the highest level of obesity in Western Europe (29% of adults are obese, and 64% are overweight or obese).”

And research shows that anti-obesity medications “are also beneficial for cardiovascular diseases, such as stroke as well as dementia, which has led to [them] being considered first-line options for some of these conditions, further increasing their potential use,” they add. 

“To complicate matters further, the growing use of [anti-obesity medications] in children, typically over the age of 12, has caused considerable debate, likely increasing the risks of ocular complications in later life,” they suggest.

Recent clinical studies on these drugs “seem to offer new hope for some conditions, such as age related macular degeneration and uveitis,” they highlight, “but with potential risks of severe, though rare, ocular complications, such as ION, for others.”

It isn’t clear, however, whether the weight regain constitutes both fat and muscle, or mainly fat. Previous studies have suggested that lean body mass – including muscle – can constitute up to 40% of total weight lost during treatment.

More than a billion people worldwide are living with obesity, which increases the risk of diseases such as 2 diabetes, cardiovascular disease and cancer. Weight loss can help mitigate these complications, but losing weight through diet and exercise alone can prove challenging.

In the past few years, a new generation of weight loss drugs has emerged that target a protein known as the glucagon-like peptide 1 receptor (GLP-1R). These drugs help control blood sugar and reduce appetite, and clinical trials have shown they can lead to weight losses of 15 to 20%.

Approximately half of all patients who begin taking these drugs discontinue their use within the first year, however, and three-quarters have stopped after two years. This is likely to be due to their potential side effects and to limited access under insurance coverage policies and national prescribing guidelines.

A team of students at Trinity College, University of Cambridge, has investigated the impact of stopping the medication, modelling the trajectory of weight regain over 12 months and beyond. Their findings are published today in eClinicalMedicine.

The team first carried out a systematic review of existing scientific and medical literature, identifying and summarising all the relevant evidence. They followed this with a meta‑analysis, which pools the results of multiple studies to estimate an overall effect. This approach allowed them to draw more robust conclusions from studies which, on their own, may provide insufficient evidence and sometimes disagree with each other.

In total, the team examined 48 relevant studies, comprising 36 randomised controlled trials (RCTs) and 12 non-randomised studies.

As most of these studies only followed patients for a few weeks after stopping the drugs, the team selected the six RCTs (comprising more than 3,200 individuals in total) that followed patients for up to 52 weeks after discontinuation of the weight loss drugs. They used these to model the trajectory of weight regain, including to extrapolate beyond 52 weeks.

The model estimated that when individuals stopped taking the medication, they underwent rapid initial weight regain, which slowed progressively. By 52 weeks, individuals had regained 60% of their original weight loss.

At 60 weeks, weight regain begins to plateau and is projected to taper off at 75% of the original weight loss. This means that 25% of the initial weight loss may be sustained in the long term. For an individual who had lost a fifth of their weight while on the drugs, this would correspond to a sustained weight reduction of around 5%.

Weight regain trajectories appeared broadly similar for the different types of weight loss drugs targeting GLP-1R.

Brajan Budini, a medical student at the School of Clinical Medicine and Trinity College, University of Cambridge, said: “Drugs such as Ozempic and Wegovy act like brakes on our appetite, making us feel full sooner, which means we eat less and therefore lose weight. When people stop taking them, they are essentially taking their foot off the brake, and this can lead to rapid weight regain.”

The researchers say there are several reasons why people may not return to their original weight even a year after stopping the medications. One reason is that by reducing appetite, these drugs may help individuals develop healthier eating habits, such as reduced portion sizes or more nutritionally-balanced meals, and these habits may persist even after treatment is discontinued. The drugs may also affect the body long-term, altering hormone levels and ‘resetting’ the brain’s appetite control mechanisms.

Steven Luo, also a medical student at the School of Clinical Medicine and Trinity College, said: “When stopping weight loss drugs, doctors and patients should be aware of the potential for weight regain and consider ways to mitigate this risk.

“It’s important that people are given advice on improving their diet and exercise, rather than relying solely on the drugs, as this may help them maintain good habits when they stop taking them.”

There are significant concerns about the long-term consequences of GLP-1R drugs on body composition, with studies indicating that 40 to 60% of the weight lost during treatment is muscle. It was not clear whether individuals regain both fat and muscle.

Budini added: “Our projections show that even though people regain most of the weight they have lost, they still maintain some of the weight loss, but what we currently don’t know is if the same proportion of lean mass is recovered. If the regained weight is disproportionately fat, individuals may ultimately be worse off than before in their fat-to-lean mass ratio, which may have adverse consequences for their health.”

The researchers say there are several limitations to their study. Most importantly, the trial data used to fit their model only extended to 52 weeks after cessation. They also restricted their analysis to studies reporting at least 3kg on-treatment average weight loss.

Reference

Budini, B. & Luo, S. et al. Trajectory of weight regain after cessation of GLP-1 receptor agonists: a systematic review and nonlinear meta-regression. eClinicalMedicine; 4 Mar 2026; DOI: 10.1016/j.eclinm.2026.103796

But people with high blood sugar often don’t achieve those benefits from exercise, especially the ability to use oxygen efficiently. They’re at higher risk for heart and kidney disease, but high blood sugar can prevent their muscles from taking up oxygen more effectively in response to exercise.

For them, a new study suggests the answer could be eating not less fat, but more.

The study by exercise medicine scientist Sarah Lessard, published Feb. 25 in Nature Communications, found that a high-fat, ketogenic diet reduced high blood sugar, or hyperglycemia, in mice, and their bodies were more responsive to exercise.

“After one week on the ketogenic diet, their blood sugar was completely normal, as though they didn’t have diabetes at all,” said Lessard, associate professor at the Fralin Biomedical Research Institute at VTC Center for Exercise Medicine Research. “Over time, the diet caused remodeling of the mice’s muscles, making them more oxidative and making them react better to aerobic exercise.”

The ketogenic diet is named for its ability to induce ketosis, a metabolic state that shifts the body to burning fat for fuel instead of sugar. The diet is controversial because it calls for eating high-fat, very low-carbohydrate foods, which is counter to the low-fat diet historically urged by health advocates.

However, the keto diet has been linked to benefits for people with some diseases, including epilepsy and Parkinson’s disease. In the 1920s, before the discovery of insulin, it was a way to manage diabetes because of its ability to lower blood sugar.

In earlier research, Lessard found that people with high blood sugar had lower exercise capacity. She wondered if the diet might improve the response to exercise, leading to higher exercise capacity.

Mice were fed a high-fat, low-carbohydrate diet and exercised on running wheels. The mice developed more slow-twitch muscle fibers, which give better endurance.

“Their bodies were more efficiently using oxygen, which is a sign of higher aerobic capacity,” Lessard said.

Lessard said exercise positively affects virtually every tissue in our body, even fat tissue, but she and others are seeing that the greatest health improvements won’t come with diet or exercise alone.

“What we’re really finding from this study and from our other studies is that diet and exercise aren’t simply working in isolation,” said Lessard, who also holds an appointment in the Department of Human Foods, Nutrition, and Exercise in Virginia Tech’s College of Agriculture and Life Sciences. “There are a lot of combined effects, and so we can get the most benefits from exercise if we eat a healthy diet at the same time.”

Next, Lessard would like to continue her research in human subjects to see if they gain the same benefits from the keto diet seen in mice.

She also notes that the keto diet is challenging to follow. A less restrictive regimen, such as the Mediterranean diet, might be easier for people to follow and still be effective. That diet can also keep blood sugar low, while including carbohydrates from unprocessed fruits, vegetables, and whole grains rather than restricting carbohydrates altogether.

“Our previous studies have shown that any strategy you and your doctor have arrived at to reduce your blood sugar could work,” she said.

It is the first in vivo study to systematically evaluate the effects of repeated SNAC exposure on gut microbiota composition, function, and metabolic outcomes. In an animal model extending 21 days, researchers identified:

• Lower levels of beneficial gut bacteria that help break down dietary fibre
• Reduced short-chain fatty acids which protect the gut lining and help regulate inflammation
• Higher levels of blood inflammatory markers
• An increase in liver weight, which can reflect low-grade inflammation
• A smaller caecum – the part of the intestine where gut bacteria break down fibre and produce protective compounds
• Reduced levels of a brain-derived protein associated with cognitive impairment.

While the study does not directly show that SNAC causes harm, the findings suggest that the absorption enhancer may have biological effects beyond simply helping semaglutide work in pill form.

Semaglutide is the active ingredient in weight loss medicines. When injected, it enters the bloodstream directly. In tablet form, it relies on SNAC to protect it from enzymatic degradation in the stomach and enable absorption into the bloodstream. Without SNAC, oral semaglutide would not work.

With the United States approving the Wegovy tablet late last year, and expectations that it will be cheaper and more convenient than injections, long‑term daily exposure to SNAC is likely to increase substantially.

Globally, about 890 million people and 160 children live with obesity, equivalent to one in eight people worldwide. The United States has the highest obesity rate among OECD countries with 43% of people aged 15+ living with the condition; Australia ranks sixth at 31%, above the OECD average of 25%.

In Australia prescriptions for drugs such as Ozempic and Wegovy have risen sharply in recent years.

Lead author and Adelaide University PhD candidate Amin Ariaee says the rapid growth in oral obesity treatments that utilise SNAC makes it critical to understand its full biological impact, in order to mitigate any longer-term adverse health effects.

“Obesity is a complex, chronic disease with serious health consequences. These medicines are highly effective and are helping many people,” Ariaee says.

“But as oral versions become more widely used, we need to understand what repeated, long-term exposure to all ingredients in the pill means for the body – not just the active drug.

“While SNAC enables semaglutide to be taken as a tablet, our study found that it was also associated with shifts in potentially harmful gut bacteria, elevated inflammatory markers and depletion of proteins linked to cognitive impairment. These findings warrant further investigation.”

Senior Research Fellow Dr Paul Joyce says that as these are early results from animal models – not humans – the findings should be interpreted carefully and highlight an important research gap.

“Importantly, our findings do not prove that SNAC causes harm in humans,” Dr Joyce says.

“However, they do show that the ingredient enabling these tablets to work may have adverse biological effects beyond drug absorption.

“These medicines are typically taken daily and often for long periods. As their use expands globally, it becomes increasingly important to evaluate all components of these therapies, not just the active compound.”

Obesity is a significant public health problem that has become a leading cause of death in high-income countries. Worldwide adult obesity has more than tripled since 1975, according to the WHO. In 2022, 2.5 billion adults were overweight. Of these, 890 million were living with obesity.

Intermittent fasting has surged in popularity in recent years, fuelled by social media, lifestyle influencers, and claims of rapid weight loss and metabolic benefits.

No meaningful difference in weight loss

Researchers analysed evidence from 22 randomized clinical trials involving 1,995 adults across North America, Europe, China, Australia, and South America. Trials examined multiple forms of intermittent fasting, including alternate-day fasting, periodic fasting, and time-restricted feeding. Most studies followed participants for up to 12 months.

The review compared intermittent fasting with traditional dietary advice and with no intervention. Intermittent fasting did not appear to have a clinically meaningful effect on weight loss compared to standard dietary advice or doing nothing.

Reporting of side effects was inconsistent across trials, making it difficult to draw firm conclusions. The evidence base remains limited, with only 22 trials, many with small sample sizes and inconsistent reporting.

“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.

Hype outpaces the evidence

Garegnani also cautioned against the hype surrounding 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.”

Few trials have looked at the long-term results of intermittent fasting. “Obesity is a chronic condition. Short-term trials make it difficult to guide long-term decision-making for patients and clinicians,” Garegnani added.

The majority of the included studies enrolled predominantly white populations in high-income countries. As obesity is a rapidly growing crisis in low- and middle-income countries, further research is needed in these populations.

The authors therefore warn that these results may provide clues, but cannot be extrapolated to the entire population, as they may vary depending on sex, age, ethnic origin, disease status, or underlying eating disorders or behaviours.

“With the current evidence available, it’s hard to make a general recommendation,” said Eva Madrid, senior author from Cochrane Evidence Synthesis Unit Iberoamerica. “Doctors will need to take a case-by-case approach when advising an overweight adult on losing weight.”

The findings were published Feb. 9, 2026 in The Lancet.

The study’s lead author, Professor Mika Kivimaki (University College London – Faculty of Brain Sciences), said, “Obesity is well known as a risk factor for metabolic syndrome, diabetes, cardiovascular disease, and many other chronic conditions. Here we have found robust evidence that obesity is also linked to worse outcomes from infectious diseases, as becoming very ill from an infection is markedly more common among people with obesity.”

The new analysis included pooled data on 67,766 adults from two Finnish studies and 479,498 from the UK Biobank. The average age at baseline was 42 years old for the Finnish cohorts and 57 years old for the UK Biobank cohort.

Participants had their body mass index (BMI) assessed when they entered the studies (1998–2002 in the Finnish studies; 2006–10 in UK Biobank), and they were subsequently tracked for an average of 13-14 years.

They were followed through national hospitalization and mortality registries for hospital admission and death due to infectious disease. At baseline, the subjects had no recent history of infection related hospitalization.

For BMI, they were classed as having healthy weight (18.5–24.9 kg/m²), overweight (25.0–29.9 kg/m²) or obesity — class I obesity (30.0–34.9 kg/m²) class II (35.0–39.9 kg/m²) or class III (≥40.0 kg/m²).

During follow-up, there were 8,230 infection cases in the Finnish cohorts and 81, 945 in UK Biobank cohort.

The investigators reported that subjects with obesity, defined as BMI ≥30 kg/m², had a 70% higher risk of hospitalization or death from any infectious disease compared to those with a BMI between 18.5 to 24.9.

Notably, subjects with the most severe obesity (BMI ≥40 kg/m²) had three times the risk of death from infection compared to those with a healthy weight.

Author Dr Solja Nyberg, University of Helsinki (Finland), says “Our findings suggests that people living with obesity are significantly more likely to become severely ill or to die from a wide range of infectious diseases. As obesity rates are expected to rise globally, so will the number of deaths and hospitalizations from infectious diseases linked to obesity.”

Kivimäki added, “Our finding that obesity is a risk factor for a wide range of infectious diseases suggests that broad biological mechanisms may be involved. It is plausible that obesity weakens the immune system’s ability to defend against the infectious bacteria, viruses, parasites or fungi, therefore resulting in more serious diseases. Evidence from trials of GLP-1 weight-loss drugs fits with this, as reducing obesity also appears to lower the risk of severe infections, alongside many other health benefits. That said, additional research is required to confirm the mechanisms underlying these associations.”

The study, which was based on an online survey conducted in 2025 among 406 active TikTok users, found that the platform affects dietary preferences through various channels of influence.

“Nowadays, young people are aligning most of their dietary habits with the content they might see in social media,” said corresponding author Artur Strzelecki, PhD, of the University of Economics in Katowice, located in Poland. “Culinary trends presented on TikTok’s videos can determine what young people will eat, which food places they visit, and how they evaluate presented recipes.”

Seven hypotheses were supported by survey results, indicating that each of the following likely influence attitudes and behaviors around food: the perceived usefulness of TikTok; the platform’s entertainment content; the virality of culinary recipes; influencers’ reviews of dining venues; social influence (opinions of family, friends, and coworkers); bonds with content creators; and users’ attitudes toward culinary trends.

URL upon publication: https://onlinelibrary.wiley.com/doi/10.1111/ijcs.70184

The Viewpoint, “When Nutrition Science is Ignored/Potential Public Health Cost of the 2025 Dietary Guidelines,” expresses concerns that the new guidelines ignored the advice of the 2025 Dietary Guidelines Advisory Committee, which emphasized limiting meat, added sugars, and high-sodium foods in favor of fruits, vegetables, whole grains, legumes, nuts and plant proteins, and, instead, release guidelines that was not based on scientific evidence.

“This is more than a scientific concern—it represents a regression in evidence-based public health policy,” the article says. “Poor diet, specifically a dietary pattern high in sodium, saturated fat, fried food, refined grains, animal protein, cholesterol, and added sugar is the leading cause of death and disability in the US, surpassing tobacco and inactivity.”

The authors urge future dietary guidelines to follow scientific-backed recommendations. When they don’t, the rationale should be explained, and any commercial or political considerations should be revealed, they wrote.

“In the meantime,” the commentary says, “clinicians, health systems, and advocacy organizations must reaffirm the science. Diets rich in whole grains, fruits, vegetables, legumes, nuts, and seeds are foundational to cardiovascular and metabolic health, and have been shown to reduce systemic inflammation and favorably influence the composition and function of the gut microbiome.”

Dr. Neal Barnard, one of the piece’s three authors and president of the Physicians Committee for Responsible Medicine, says the new guidelines should be rewritten to reflect evidence-based nutrition standards.

“As currently written,” Dr. Barnard says, “the Dietary Guidelines dangerously promote animal products, the biggest cause of chronic disease. They must be revamped to eliminate industry influence and comport with the science, which shows the healthiest diet is one that focuses on plants.”

The Physicians Committee filed a petition Jan. 8 with the Offices of Inspector General for the Department of Health and Human Services and the U.S. Department of Agriculture asking for the 2025-2030 Dietary Guidelines to be withdrawn and reissued because of rampant industry influence, including by the meat and dairy industries. Of nine authors of a new scientific report underlying the guidelines, at least seven had industry ties. The authors declared receiving research funding or other compensation from the National Cattlemen’s Beef Association, the Texas Beef Council, General Mills, the National Dairy Council, and the National Pork Board, among other companies.