A team of 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) has demonstrated that limiting food intake to an eight-hour window helps maintain weight loss 12 months after the end of the intervention in overweight or obese adults.
The research has revealed that intermittent fasting – specifically the method popularly known as 16:8, in which participants fast for 16 hours and are allowed to eat during the remaining eight hours – is an effective strategy for maintaining weight loss in the medium term. The study shows that these benefits persist one year later, regardless of whether the eight-hour eating window occurs early in the day (between 9 a.m. and 5 p.m., known as early fasting) or later (between 1 p.m. and 9 p.m., known as late fasting), compared to people who maintain their usual eating routine for 12 hours or more.
The results show that both the early-fasting and late-fasting groups managed to maintain significantly greater weight loss after 12 months. Furthermore, the early-fasting group maintained a greater reduction in fat mass. According to the researchers, these findings suggest that this type of nutritional intervention is not only feasible and effective in the short term but now also demonstrates sustainable effects over time.
Body Composition Assessment One Year Later
The study, recently published in Clinical Nutrition, involved 99 adults – half of whom were women – who were overweight or obese. During the first 12 weeks, participants were divided into four groups, all of which followed a Mediterranean diet education program: a control group that maintained its usual eating window (12 hours or longer), an early fasting group (an 8-hour window beginning before 10:00 a.m.), a late fasting group (an 8-hour window beginning after 1:00 p.m.), and a self-selected group where participants chose their own 8-hour eating window.
Changes in weight, fat mass, and fat-free mass were measured before and after the 12-week intervention, as well as one year after the study ended. This study is part of a larger project whose main results have been published in the prestigious journal *Nature Medicine*, where it was observed that participants who practiced TRE, regardless of their eating schedule, lost an average of 3–4 kilos more than the group that received only nutritional recommendations.
Dr. Alba Camacho Cardeñosa, a researcher at the University Joint Institute for Sport and Health (iMUDS) at the University of Granada (UGR) 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.” In addition, the researchers highlight 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 researchers emphasise that an intervention involving just 12 weeks of intermittent fasting may represent an effective medium-term strategy for weight control in overweight or obese adults. Since both early- and late-day fasting regimens have been shown to be effective, the findings offer valuable flexibility for patients to choose the schedule that best suits their lifestyle, thereby improving adherence and success in obesity treatment.
Source: University of Granada
