Does Weight Stay Off After Time-Restricted Eating? 12-Month Data

A 12-week program of eating within an 8-hour window left adults with overweight or obesity lighter than a usual-care group 12 months after the program ended. That is the headline of a follow-up to a randomized trial from the University of Granada, published online on 2 June 2026 in Clinical Nutrition. Two details deserve as much attention as the headline: only 26% of participants reported doing time-restricted eating during the follow-up year, and the reduction in fat-free mass persisted alongside the weight loss.

What the study did

The trial recruited 99 adults with overweight or obesity. Half were women, the average age was 49.0 years, and the average body mass index was 32.0. They were randomly assigned to one of four groups for 12 weeks:

Group	People	Eating pattern during the 12 weeks
Usual care	25	Kept their habitual eating window of 12 hours or more
Early time-restricted eating	25	8-hour window starting before 10:00
Late time-restricted eating	27	8-hour window starting after 13:00
Self-selected time-restricted eating	22	8-hour window at a time the participant chose

All four groups, usual care included, received a Mediterranean diet education program. So the comparison is not "fasting versus nothing". It is an eating window plus diet education versus diet education alone.

Body weight, fat mass and fat-free mass were measured at baseline, at 6 weeks, at 12 weeks (the end of the program) and again 12 months after the program ended. The measurements came from a multi-frequency segmental bioelectrical impedance analyzer.

What it found a year later

The abstract reports the 12-month comparisons against usual care like this:

• Body weight. The early group (p = 0.01) and the late group (p = 0.02) maintained significantly greater weight loss than usual care.
• Fat mass. There was a significant fat mass difference between the early group and usual care (p = 0.04). The abstract's wording here is awkward ("fat mass loss remained significantly lower"). Read with the other results, it most plausibly means fat mass stayed lower in the early group, but the abstract gives no figures that would confirm the direction.
• Fat-free mass. The reduction in fat-free mass persisted in the late group (p = 0.04) and showed what the authors call a tendency in the early group (p = 0.051), both compared with usual care.
• All three schedules together. When the early, late and self-selected groups were pooled, the differences from usual care were reinforced.

The abstract does not single out the self-selected group as significantly different from usual care on its own. With 22 people in it, that group was also the smallest.

One thing you will not find here is a number of kilograms. The abstract reports that the differences were statistically significant, not how large they were, so this post cannot tell you how much weight stayed off. The authors' own background section describes the weight loss from time-restricted eating in general as modest.

Most people did not keep the habit

During the 12-month follow-up, 26% of participants reported having engaged in time-restricted eating. Put the other way around, roughly three in four did not report it.

That figure cuts in two directions. It suggests a short program can leave a difference on the scale a year later even when most people stop following the eating window. It is also a plain statement about adherence: most people did not carry on with an 8-hour window once the program ended.

The abstract does not say whether the people who kept the habit were the ones who kept the weight off.

What happened to lean mass

Fat-free mass is everything in your body that is not fat: muscle, but also water, bone and organs. When people lose weight by any method, some of the loss usually comes from fat-free mass, and the general goal is to keep that share small.

In this trial the reduction in fat-free mass was still there a year later in the time-restricted eating groups compared with usual care.

Two cautions apply. Bioelectrical impedance estimates fat-free mass indirectly and is sensitive to how much water the body is holding, so a change in fat-free mass is not the same thing as a measured change in muscle. And the abstract gives no amounts, so there is no way to judge from it whether the reduction was large or small.

What it does not show

• Small groups. Each arm had between 22 and 27 people.
• No effect sizes in the abstract. Significance tells you a difference is unlikely to be chance. It does not tell you how big the difference is.
• One population. These were adults in their late forties on average, with overweight or obesity, in Spain, all receiving Mediterranean diet education.
• It did not compare fasting with a calorie-counting diet. The control group ate as usual.

The authors conclude that a 12-week program "may represent" an effective long-term strategy for maintaining weight loss up to 12 months.

What this means if you fast

An 8-hour eating window is the pattern usually called 16:8. This trial suggests that the timing of the window (early or late) mattered less than having one, since both the early and late groups held on to more weight loss than usual care. Our guide to choosing a fasting schedule for your lifestyle walks through the options.

The lean mass result is a reminder that the scale is not the whole story. This study did not test ways to protect muscle, so it cannot tell you what works, but what you eat inside the window deserves thought, which is the subject of our post on structuring your eating window.

This is general information, not medical advice. If you are pregnant or breastfeeding, have diabetes or take blood-sugar medication, have a history of eating disorders, take other regular medication, or are under 18, talk to a doctor before fasting.

QoFast is a fasting tracker app for iPhone and Android with intermittent plans including 16:8, 18:6, 20:4, OMAD and custom windows, plus fasting history and streaks so you can see whether a habit is holding. It gives general information, not medical advice, and it is free to download with an optional Pro subscription: App Store and Google Play.

FAQ

Does weight come back after you stop time-restricted eating? In this trial, the early and late groups still showed significantly greater weight loss than usual care 12 months after a 12-week program. The abstract does not report how much weight was regained or kept off in kilograms.

Is an early or a late eating window better for keeping weight off? Both the early window (starting before 10:00) and the late window (starting after 13:00) maintained greater weight loss than usual care. The abstract does not report a direct comparison between the two.

Did people lose muscle? The study measured fat-free mass, which includes muscle, water, bone and organs, using bioelectrical impedance. The reduction in fat-free mass persisted at 12 months in the late group and tended to in the early group. That is not a direct measurement of muscle.

Sources

• Camacho-Cardenosa A, 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, published online 2 June 2026. DOI: 10.1016/j.clnu.2026.106706, PubMed 42302513. Trial registration: ClinicalTrials.gov NCT05310721.