obesity

An international team analyzed data from 262 clinical trials involving 100,000 people, which evaluated a total of 19 currently available obesity drugs, including GLP-1 analogs such as semaglutide and tirzepatide. Overall, the results indicate that, despite substantial weight loss, most of the drugs do not significantly improve quality of life, and few show cardiovascular benefits after one year of treatment. Furthermore, those that achieved greater weight loss were often associated with more side effects. The study is published in The BMJ.

According to the findings of two clinical trials published in Annals of Internal Medicine, adults at high cardiometabolic risk who slept almost 80 minutes less per night for six weeks gained nearly half a kilogram on average and experienced an increase in waist circumference. The studies included a total of 95 participants, all of whom had a habitual sleep duration of at least seven hours per night. Sleep restriction was also associated with increased leptin levels, a hormone involved in regulating energy balance, and with greater sedentary time.

An international team has analyzed data collected between 1990 and 2024 from nearly one million people in seven countries regarding their body mass index, cholesterol levels, and blood pressure. The results indicate that, in adults over 40, these levels have been converging, becoming quite similar overall in obese and non-obese individuals, possibly due to the widespread use of treatments. Despite these findings, the authors note that there are other risks associated with obesity not included in the study, such as diabetes, kidney disease, and cancer, among others. The work is published in The Lancet. 

A team from the UK has analyzed body mass index (BMI) and genetic variants associated with obesity in four generations of Britons born in 1946, 1958, 1970, and 2001—that is, before and after the rise in obesity rates. The results indicate that people with a genetic predisposition to a high BMI are likely more susceptible than others to changes in their environment that promote obesity, such as those that have occurred in recent decades related to ultra-processed food and sedentary lifestyles. In other words, although genetics has not changed, the obesogenic environment has strengthened its association with obesity. The work is published in Plos Genetics.  

A global analysis of data from more than 232 million people shows that the rise in obesity has slowed or stabilised in some high-income countries since the 1990s among children and adolescents, and, a decade later, among adults. In Spain, this stabilisation or even a slight decline is also observed. In most low- and middle-income regions, the prevalence of obesity continues to increase and, in some cases, has already surpassed that of more developed economies. The study, published in Nature, included 4,050 studies covering the period from 1980 to 2024 across 200 countries.

In the treatment of obesity, maintaining weight loss is the most difficult phase. Two independent clinical trials published in Nature Medicine have adopted two different strategies to achieve this. The first is a phase 3b trial involving the GLP-1 drug orforglipron, administered orally on a daily basis for 52 weeks. This trial included 376 adults in the United States who had already completed 72 weeks of injectable treatment with tirzepatide or semaglutide. Almost 75% and 80% respectively of patients on each injectable drug maintained their weight loss. The second trial involved 90 obese adults from the Netherlands who followed a low-calorie diet for eight weeks and then received a daily supplement of the bacterium Akkermansia muciniphila for 24 weeks, alongside a healthy diet. Although those who received the supplement regained more than 13% of the weight initially lost, those who took the placebo regained almost 33%.

A Danish clinical trial involving 108 adults with obesity who were seeking treatment for alcohol use found that a weekly injection of semaglutide reduced the number of heavy drinking days. This decrease averaged about 12 days—50% greater than the eight-day reduction observed in the placebo group. The study is published in The Lancet and was funded by the Novo Nordisk Foundation, the company that develops these drugs.

A study with Spanish participation has discovered in mice that semaglutide can improve the condition of non-alcoholic fatty liver disease not only through weight loss, but also independently, which would explain why some patients improve with minimal weight loss. “We are not saying that weight loss is unimportant, as many things improve when patients lose weight. But now we know that weight should not be the only measure of success, because GLP-1 drugs will improve liver health regardless of whether the patient loses weight or not,” the authors, who published the results in Cell Metabolism. 

GLP-1 medicines for the treatment of obesity show considerable variability between individuals. Using data from 23andMe, scientists at this genetic testing company conducted genome-wide association studies in nearly 28,000 people treated with these drugs, analysing self-reported weight loss and adverse effects. Their findings, published in Nature, identified variations in two genes involved in gut hormone pathways that regulate appetite and digestion, although the authors caution that the effects of genetics appear to be modest.

Oral semaglutide is not effective in slowing the progression of the disease in patients with mild Alzheimer’s disease, according to the findings of the first large-scale, randomised phase 3 clinical trials published in The Lancet. In these trials, around 3,800 patients aged between 55 and 85 with a confirmed diagnosis and mild symptoms received up to 14 mg daily of oral semaglutide or a placebo. After two years, no significant difference in disease progression was observed.