To control weight, it is not only important to pay attention to what we eat, but also when we do it, and a new study published in the International Journal of Behavioral Nutrition and Physical Activity has identified two habits that are related to a lower body mass index. (BMI) long term: maintain a prolonged fast overnight and eat breakfast early.
The research has been led by the Barcelona Institute for Global Health (ISGlobal) and included 7,074 volunteers between 40 and 65 years old belonging to the GCAT | Genomes for Life, a project led by the Germans Trias i Pujol Research Institute (IGTP). In 2018, participants completed questionnaires about their weight, height, eating habits, meal times, lifestyle, and socioeconomic status. Five years later, in 2023, more than 3,000 of them made a follow-up visit, during which they were measured again and answered a new questionnaire.
“Our results, in line with those of other recent studies, suggest that extending overnight fasting could help maintain a healthy weight as long as it is accompanied by an early dinner and early breakfast. We think this might be because eating earlier in the day aligns more with circadian rhythms and allows for better calorie burning and appetite regulation, which can help maintain a healthy weight. However, it is still early to draw definitive conclusions, so recommendations will have to wait until we have more robust evidence,” explained Luciana Pons-Muzzo, a researcher at ISGlobal during the study and currently at IESE Business School.
Health benefits of overnight fasting
When analyzing the data by sex, it was observed that women, in general, had a lower BMI, greater adherence to the Mediterranean diet, less alcohol consumption, worse mental health and greater responsibility in managing the home or office. family care, compared to men.
The team used “cluster analysis” to group participants based on common characteristics. A small group of men who ate their first meal after 2:00 p.m. and fasted for about 17 hours stood out for leading less healthy lifestyles (greater alcohol and tobacco consumption, less physical activity, and worse adherence to the Mediterranean diet). Additionally, they had lower educational levels and were more likely to be unemployed. This pattern was not observed in women.
We think that eating earlier in the day is more in line with circadian rhythms and allows us to burn calories better and regulate our appetite.
“There are various ways to practice what is known as ‘intermittent fasting’ and our study would be related to one of them, which is overnight fasting. What we observed in a subgroup of men who do intermittent fasting by skipping breakfast is that this practice has no effects on body weight. Other intervention studies in patients with obesity have shown that this tactic is not more effective than reducing calorie intake in reducing body weight in the long term,” says Camille Lassale, ISGlobal researcher and co-author of the study.
Anna Palomar-Cros, another ISGlobal researcher at the time of the study and now at IDIAP Jordi Gol, points out that this research is part of an emerging field known as “chrononutrition”, which studies not only what we eat, but when and how often. . According to Palomar-Cros, unusual eating patterns could conflict with the circadian system, which regulates day-night cycles and associated physiological processes.
This work continues ISGlobal’s line of research on chrononutrition. In previous studies, the team of scientists found that eating dinner and breakfast early was linked to a lower risk of cardiovascular disease and type 2 diabetes.
Source: Barcelona Institute for Global Health (ISGlobal)
