Researchers have found that intermittent fasting can help adults with overweight or obesity maintain weight loss for up to a year after completing a structured dietary intervention, regardless of when they schedule their daily eating window. The study, led by 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), suggests that restricting food intake to eight hours a day may offer sustainable benefits for weight management.
The research focused on the popular 16:8 approach to intermittent fasting, in which people fast for 16 hours and consume food during an eight-hour window. Participants who followed either an early eating schedule, between approximately 9 a.m. and 5 p.m., or a later schedule, between 1 p.m. and 9 p.m., maintained significantly greater weight loss after 12 months than those who continued eating over their usual window of 12 hours or longer. The early fasting group also maintained a greater reduction in fat mass, although both schedules produced lasting benefits.
Published in Clinical Nutrition, the study involved 99 adults, about half of whom were women, with overweight or obesity. During a 12-week intervention, all participants received education about the Mediterranean diet and were assigned to one of four groups: a control group that maintained its normal eating schedule, an early fasting group, a late fasting group or a self-selected group that chose its own eight-hour eating window. Researchers measured body weight, fat mass and fat-free mass before and after the intervention and again one year later.
The study forms part of a larger research project whose main findings were previously published in Nature Medicine. That research showed that participants practising time-restricted eating, regardless of their chosen eating schedule, lost an average of three to four kilograms more than those who received nutritional recommendations alone. According to first author Dr Alba Camacho Cardeñosa of the University of Granada and ibs.GRANADA, the latest findings address an important question about whether the modest short-term weight loss associated with intermittent fasting can be maintained over time.
“By evaluating the participants 12 months after the intervention ended, we demonstrated that the changes in body weight persist,” Camacho Cardeñosa said. Researchers also found that approximately one in three participants chose to continue intermittent fasting independently during the year-long follow-up period. The team said this suggests that time-restricted eating may be relatively easy for some people to integrate into everyday routines, an important consideration because long-term adherence remains a major challenge in weight-management interventions.
The researchers conclude that even a 12-week period of intermittent fasting may provide an effective medium-term weight-control strategy for adults with overweight or obesity. Because both early and late eating windows produced lasting weight-loss benefits, people may have greater flexibility to choose a schedule that fits their lifestyle and daily commitments. The study, involving researchers and clinical teams in Granada and Navarra, adds to growing evidence that flexible time-restricted eating could support obesity treatment while allowing individuals to adopt an eating schedule they are more likely to maintain.
More information: Alba Camacho-Cardenosa et al, Effects of an early, late, and self-selected time-restricted eating intervention on weight loss maintenance in adults with overweight or obesity: A 12-month follow-up of a randomized controlled trial, Clinical Nutrition. DOI: 10.1016/j.clnu.2026.106706
Journal information: Clinical Nutrition Provided by University of Granada
