Research

Energy balance

The 5:2 intermittent energy restriction diet produces weight loss equivalent to standard brief lifestyle advice over 12 months, with no adverse effects on physical activity or macronutrient intake.

Try the 5:2 diet by restricting calories to 500 (women) or 600 (men) on two non-consecutive days a week. Eat normally on the other five days. Expect modest weight loss (around 2kg) over a year, similar to standard diet advice. If you struggle with hunger, know that it often decreases over time, and consider joining a support group to help you stick with it initially.

GoodSupportsHIGH confidence
5:2SH and SBA achieved similar weight-loss at six months (-1.8kg (SD = 3.5) vs -1.7kg (SD = 4.4); b = 0.23, 95%CI:-0.79–1.27, p = 0.7) and at one year (-1.9kg (SD = 4.9) vs -1.8kg (SD = 5.7), b = 0.20, 95%CI:-1.21–1.60, p = 0.79)... 5:2SH had no negative effect on fat and fiber intake and physical activity compared to SBA.
Peter Hájek et al. · PLoS ONE · 2021

Why this rating

Randomized controlled trial with 300 participants, though adherence dropped significantly over time.

Source

A randomised controlled trial of the 5:2 diet

Peter Hájek et al. · PLoS ONE · 2021

DOI 10.1371/journal.pone.0258853

rct · n=300Cited 34×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

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