Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trials
BMJ 2025 systematic review and network meta-analysis of 99 RCTs (n=6,582) finds all intermittent fasting and continuous energy-restriction strategies reduced weight versus ad libitum diets; versus continuous energy restriction, alternate-day fasting showed additional mean weight loss (−1.29 kg; moderate certainty) and small advantages over other IF templates, with lipid signals differing between IF comparisons and no pooled differences for HbA1c or HDL across key contrasts.
Design
- Corpus: 99 RCTs, n = 6,582 adults (healthy n = 720; existing conditions n = 5,862)
- Comparators: intermittent fasting schedules vs continuous energy restriction vs ad libitum
- Primary outcome: body weight; secondary cardiometabolic risk markers
- Note: BMJ erratum 2025 Aug 18;390:r1737 (doi: 10.1136/bmj.r1737) exists—check figures if numbers shift in your PDF build
Weight outcomes (abstract highlights)
- All IF + CER strategies reduced weight vs ad libitum
- Alternate-day fasting vs continuous energy restriction: MD −1.29 kg (95% CI −1.99 to −0.59; moderate certainty) — only IF template with additional loss vs CER in primary framing
- Alternate-day vs time-restricted eating: MD −1.69 kg (95% CI −2.49 to −0.88; moderate certainty)
- Alternate-day vs whole-day fasting: MD −1.05 kg (95% CI −1.90 to −0.19; moderate certainty)
- ≥24 weeks trials (n = 17): abstract states benefits vs ad libitum persisted for weight in longer windows
Lipid contrasts (abstract)
Alternate-day fasting lowered total cholesterol, triglycerides, and non-HDL vs time-restricted eating; time-restricted eating slightly raised TC / LDL / non-HDL vs whole-day fasting in pooled comparisons.
Nulls (abstract)
No differences among IF, CER, and ad libitum for HbA1c and HDL in the contrasts summarised.
Publication
Semnani-Azad Z, Khan TA, Chiavaroli L, et al. BMJ. 2025 Jun 18;389:e082007. doi: 10.1136/bmj-2024-082007. PMID 40533200.
Outcomes
- Alternate-day fasting vs continuous energy restriction: mean body-weight difference −1.29 kg (95% CI −1.99 to −0.59; moderate GRADE certainty per abstract).
- Alternate-day vs time-restricted eating: −1.69 kg (95% CI −2.49 to −0.88); alternate-day vs whole-day fasting: −1.05 kg (95% CI −1.90 to −0.19)—both moderate certainty in abstract.