An eight-hour eating window helped adults maintain weight loss one year after a 12-week intervention.
For many people trying to lose weight, the hardest part begins after the diet ends. The scale may move during a structured program, but keeping that weight off months later is often the real test.
Research 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 limiting eating to an eight-hour daily window may help overweight or obese adults maintain weight loss one year after the intervention ends.
The approach is a form of intermittent fasting known as 16:8. Participants fast for 16 hours and eat during the remaining eight hours. The study found that weight maintenance benefits were still visible 12 months later, whether people ate earlier in the day (between 9 a.m. and 5 p.m., known as early fasting) or later in the day (between 1 p.m. and 9 p.m., known as late fasting), compared with people who kept their usual eating schedule of 12 hours or more.
Both the early fasting and late fasting groups maintained significantly greater weight loss after one year. The early fasting group also kept off more fat mass, suggesting that when the eating window occurs may matter for body composition, even though both schedules helped with weight control.
Body Composition Assessment One Year Later
The study, published in Clinical Nutrition, the official journal of the European Society for Clinical Nutrition and Metabolism, included 99 overweight or obese adults, half of whom were women. During the first 12 weeks, all participants received education on the Mediterranean diet, but they followed different eating schedules.
One group continued its usual eating window (12 hours or longer). A second group followed early fasting (an 8-hour window beginning before 10:00 a.m.). A third group followed late fasting (an 8-hour window beginning after 1:00 p.m.). A fourth group chose its own eight-hour eating window.
That design helped the researchers answer a practical question. If time-restricted eating works, does it require a strict morning schedule, or can people choose a window that fits their lives?
To track the answer, the researchers measured body weight, fat mass, and fat-free mass before and after the 12-week intervention, then measured the same outcomes again one year later. The work is part of a larger project whose main results appeared in Nature Medicine, where participants practicing TRE lost an average of 3 to 4 kilos more than those who received only nutritional recommendations, regardless of eating schedule.
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
For obesity care, the finding is important because adherence often determines whether a nutritional strategy lasts. A rigid plan may work in a trial but fail in daily life. Here, both earlier and later eating windows were associated with sustained weight benefits, giving patients more room to choose a schedule that fits work, family, and social routines.
The researchers note that a 12-week intermittent fasting intervention may offer a useful medium-term strategy for weight control in overweight or obese adults. Because both early-day and late-day schedules were effective, the results support a more flexible use of time-restricted eating as part of obesity treatment.
Reference: “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” by Alba Camacho-Cardenosa, Elisa Merchán-Ramírez, Antonio Clavero-Jimeno, Alejandro De-la-O and Manuel Dote-Montero, 2 June 2026, Clinical Nutrition.
DOI: 10.1016/j.clnu.2026.106706
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