José M. Ordovás

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.

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.  

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%.

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.

An international team has analyzed data from nearly 60 studies involving more than 48,000 children with different types of diets and compared the nutritional profile and various health parameters between those following vegan, lacto-ovo-vegetarian, and omnivorous diets. The results indicate that plant-based diets, if well-planned, can promote healthy growth with benefits such as a better cardiovascular profile and lower cholesterol levels. However, they may have difficulty achieving adequate levels of vitamins D and B12, calcium, iron, and zinc. According to the authors, the findings underscore the need for careful planning and supplementation in children following these types of diets. The study is published in Critical Reviews in Food Science and Nutrition. 

The Planetary Health Diet promotes environmentally sustainable consumption, based, among other things, on increasing vegetable intake and reducing dairy and red meat consumption. Previous studies had found an association with better human health, although there were some conflicting results. Now, a study combining two cohorts of more than 150,000 people and a meta-analysis of 37 studies involving more than three million volunteers reinforces this association, finding that greater adherence to the diet is associated with lower all-cause mortality. The results are published in the journal Science Advances.

Adipose tissue retains a ‘memory’ of obesity through cellular transcriptional and epigenetic changes that persist after weight loss, which may increase the likelihood of regaining weight, experiments in human and mouse cells show. The findings, published in Nature, could help explain the problematic ‘yo-yo effect’, the rapid weight rebound often seen with dieting. 

A US research team has identified several genes that may be associated with a strict vegetarian diet. Some of these genes have "important roles in lipid metabolism and brain function", according to the paper, which suggests that these differences could explain the ability to subsist on a vegetarian diet in those who carry these genes. The study, published in the journal PLoS ONE, used data from the UK Biobank to compare a group of more than 5,000 vegetarians with a group of more than 320,000 non-vegetarians.