Overview
- Across nearly 2,000 overweight or obese adults, intermittent fasting produced little to no difference in weight loss versus calorie‑focused dietary advice or no intervention.
- Average losses on fasting plans were about 3% of body weight within 12 months, below the roughly 5% threshold typically considered clinically meaningful.
- Some protocols, including alternate‑day fasting, showed small additional reductions in individual studies, but the differences did not reach clinical significance.
- Most trials were short, had methodological shortcomings and were conducted largely in White adults from high‑income countries, limiting long‑term confidence and generalisability.
- Review authors recommend case‑by‑case clinical guidance and call for longer, more diverse trials that track metabolic outcomes, lean mass changes and participant satisfaction.