The weight-loss idea is quite appealing: Limit your eating to a period of six to eight hours each day, during which you can have whatever you want.

Studies in mice seemed to support so-called time-restricted eating, a form of the popular intermittent fasting diet. Small studies of people with obesity suggested it might help shed pounds.

But now, a rigorous one-year study in which people followed a low-calorie diet between the hours of 8 a.m. and 4 p.m. or consumed the same number of calories anytime during the day has failed to find an effect.