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Intermittent fasting, aka time-restricted eating, can help people lose weight—but the reason why may not be complicated hypotheses about changes from fasting metabolism or diurnal circadian rhythms. It may just be because restricting eating time means people eat fewer calories overall.

In a randomized-controlled trial, people who followed a time-restricted diet lost about the same amount of weight as people who ate the same diet without the time restriction, according to a study published Friday in Annals of Internal Medicine.

The finding offers a possible answer to a long-standing question for time-restricted eating (TRE) research, which has been consumed by small feeding studies of 15 people or fewer, with mixed results and imperfect designs.