Fasting protocols range from mild time-restricted eating (TRE) to alternate-day fasting and multi-day fasts. In humans, the strongest evidence is typically for modest weight loss and some cardiometabolic changes — with important caveats around adherence, diet quality, and safety for certain populations.[1][2]
High-signal rule
If you change fasting and training and diet composition at once, you won’t know what worked.
Systematic reviews of randomized trials suggest TRE can produce modest reductions in body weight and fat mass in adults, with mixed effects across cardiometabolic markers depending on population and protocol details.[2:1][3]
Extra caution is warranted for:
If you have red-flag symptoms while fasting, stop and see: Red Flags
See: N‑of‑1 Experiments
de Cabo R, Mattson MP. Effects of Intermittent Fasting on Health, Aging, and Disease. N Engl J Med. 2019;381(26):2541–2551. doi:10.1056/NEJMra1905136 ↩︎
Moon S, Kang J, Kim SH, et al. Metabolic Efficacy of Time-Restricted Eating in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Clin Endocrinol Metab. 2022;107(12):3428–3441. https://pubmed.ncbi.nlm.nih.gov/36190980/ ↩︎ ↩︎
The Effect of Time-Restricted Eating on Cardiometabolic Risk Factors: A Systematic Review and Meta-Analysis. Nutrients. 2024. https://pubmed.ncbi.nlm.nih.gov/39519533/ ↩︎