Limiting daily food intake to an 8-hour window may help people hold on to lost weight for at least a year after they stop the diet, according to a randomized trial from the University of Granada published in Clinical Nutrition in July 2026. The finding stands out because most conventional calorie-cutting plans see the weight creep back within months.
The trial followed 99 adults who were overweight or obese through a 12-week program of time-restricted eating and then measured them again a full year later. Participants who ate within an 8-hour window lost 3 to 4 kilos more than a control group and kept the extra loss at the 12-month check-in.
Time-restricted eating simply means squeezing all meals into a set window each day and fasting for the rest. In the 16:8 approach used in Granada, that could look like eating between 9 a.m. and 5 p.m., then not eating again until the following morning.
What the Granada study found
Participants were split into four groups. One kept a usual eating window of 12 hours or more, one ate between 9 a.m. and 5 p.m., one ate between 1 p.m. and 9 p.m., and one picked its own 8-hour window. All received Mediterranean diet guidance, and the researchers tracked weight, body composition and behavior over the year that followed the intervention.
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Both the early and late fasting groups maintained significantly more weight loss than the controls at 12 months, and roughly one in three participants kept doing intermittent fasting on their own after the study ended. That is unusual in weight-loss research, where relapse rates are typically high.
"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," said Alba Camacho Cardeñosa, the study's first author and a postdoctoral researcher at ibs.GRANADA and the University Joint Institute for Sport and Health.
Timing did make a difference in one respect. The early group held on to a greater loss of fat mass than the others. Overall weight maintenance, however, looked similar whether people ate earlier or later.
Adelaide trial points the same way
A separate 18-month trial run out of Adelaide University and published in Clinical Nutrition in June 2026 tested intermittent fasting against traditional calorie counting in more than 200 adults with obesity. Both approaches produced about 7 kilograms of weight loss at six months, compared with about 2 kilograms in a standard-care group.
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The researchers reported that participants on the fasting plan found the routine easier to follow. Those on daily calorie restriction said they had to consciously watch their intake, an effort the fasting group largely avoided.
"The results of our study indicate intermittent fasting could offer an alternative pathway for people who find conventional dieting challenging," said Leonie Heilbronn, professor at Adelaide University's School of Medicine, in a statement from the university.
Starting an 8-hour window
For someone curious to try it, the practical setup is straightforward. Pick a start time that fits the day, such as 10 a.m., and eat all meals and snacks within eight hours from there. Water, plain coffee and tea outside the window are fine. Diet quality still counts, and the Granada participants layered time-restricted eating on top of Mediterranean-style meals rather than replacing food rules altogether.
Intermittent fasting is not right for everyone. People who are pregnant or breastfeeding, adolescents, anyone with a history of eating disorders, and people taking medication for diabetes or blood pressure should speak with a doctor before changing meal timing, since fasting can shift blood sugar and drug effects.
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