Intermittent fasting has become one of the most popular dietary approaches of the past decade, but a key question has always lingered: do the effects last after the program stops? A new study published in Clinical Nutrition, led by researchers at the University of Granada (UGR) in Spain, provides a clear answer — yes, and for at least 12 months.
The study followed 99 adults who were overweight or obese, with half of the participants being women. All 99 received education on following a Mediterranean diet during the first 12 weeks. They were then divided into four groups: a control group that ate across a window of 12 hours or longer, an early fasting group (9 a.m. to 5 p.m.), a late fasting group (1 p.m. to 9 p.m.), and a self-selected group that chose their own eight-hour schedule. All fasting groups followed the popular 16:8 method — 16 hours of fasting, 8 hours of eating.
One year after the 12-week intervention ended, both the early and late fasting groups had maintained significantly more weight loss than the control group. Those assigned to the early schedule also preserved a larger reduction in fat mass. Crucially, the lasting benefits did not depend on whether participants ate earlier or later in the day — both windows worked equally well. The researchers also noted that one in three participants chose to continue intermittent fasting on their own during the follow-up year, suggesting the routine is practical enough to integrate into daily life.
Knowledge takeaway: University of Granada study (Clinical Nutrition, July 2026) — 99 overweight/obese adults followed a 12-week 16:8 intermittent fasting program (early or late 8-hour window); both groups maintained significantly more weight loss than the control group one year after the program ended; the early schedule also preserved more fat mass reduction; participants who chose their own eating window saw similar results; one in three voluntarily continued fasting after the study, suggesting the approach is sustainable outside a controlled setting.