Overview
- Researchers pooled 22 randomized trials involving 1,995 adults across North America, Europe, China, Australia and South America.
- Compared with conventional dietary guidance or no intervention, intermittent fasting produced little to no additional weight loss and no clear improvement in quality of life.
- Most trials were short term—up to 12 months—with small samples, inconsistent tracking of adherence, and limited demographic diversity, constraining certainty.
- Reported average losses were modest—about 3% within 12 months—below the roughly 5% threshold often viewed as clinically meaningful.
- Authors urge case-by-case clinical advice and call for larger, longer, more diverse studies to test durability, safety and broader metabolic effects.