Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trials
Semnani-Azad Z, Khan TA, Chiavaroli L, Chen V, Bhatt HA, Chen A, Chiang N, Oguntala J, Kabisch S, Lau DC, Wharton S, Sharma AM, Harris L, Leiter LA, Hill JO, Hu FB, Lean ME, Kahleová H, Rahelic D, Salas-Salvadó J, Kendall CW, Sievenpiper JL
BMJ (Clinical research ed.) · 47 citations
How it was studied
- Design
- Meta-analysis (indexed by PubMed)
- Studied in
- People
- Main outcome
- Health markers and function
Who paid for it
- Funding
- Independent funding
- University or hospital
- University of Toronto
- Nonprofit
- European Association for the Study of Diabetes
- Government
- Canadian Institutes of Health Research
- Government
- National Institute of Diabetes and Digestive and Kidney Diseases
- Government
- NIDDK NIH HHS
- Grants
- Canadian Institutes of Health Research (129920); National Institute of Diabetes and Digestive and Kidney Diseases (P30-DK-056336)
Based on 5 listed funder(s).
Publication
- Published
- 2025-06-18 · BMJ · vol. 389 · p. e082007
- Cited
- 58 citations · more than 100% of similar papers · 11.9× the field average
- Impact
- Top 10% most cited in its field
- References
- 147 works
- Access
- Open access (hybrid journal) · CC-BY-NC
- Research areas
- Dietary Effects on Health · Diet and metabolism studies · Genetics, Aging, and Longevity in Model Organisms
- Keywords
- Intermittent fasting, Medicine, Weight loss, Meta-analysis, Anthropometry, Weight management, Randomized controlled trial, Clinical trial, Systematic review, Internal medicine, Physical therapy, MEDLINE, Obesity
- MeSH
- humans, body weight, weight loss, caloric restriction, diet, reducing, fasting, randomized controlled trials as topic, cardiometabolic risk factors, intermittent fasting
22 authors
From US, CA, DE, GB, HR, ES
- Zhila Semnani‐AzadHarvard University
- Tauseef Aized KhanSt. Michael's Hospital; University of Toronto
- Laura ChiavaroliSt. Michael's Hospital; University of Toronto
- Victoria ChenSt. Michael's Hospital; University of Toronto
- Hardil Anup BhattUniversity of Toronto
- Alisia ChenUniversity of Toronto
Abstract
Objective
To assess the effect of intermittent fasting diets, with continuous energy restriction or unrestricted (ad-libitum) diets on intermediate cardiometabolic outcomes from randomised clinical trials.
Design
Systematic review and network meta-analysis.
Data sources
Medline, Embase, and central databases from inception to 14 November 2024.
Eligibility criteria for selecting studies
Randomised clinical trials comparing the association of intermittent fasting diets (alternate day fasting, time restricted eating, and whole day fasting), continuous energy restriction, and ad-libitum diets were included.
Main outcomes
Outcomes included body weight (primary) and measures of anthropometry, glucose metabolism, lipid profiles, blood pressure, C-reactive protein, and markers of liver disease.
Data synthesis
A network meta-analysis based on a frequentist framework was performed with data expressed as mean difference with 95% confidence intervals (CIs). The certainty of the evidence was assessed using grading of recommendations assessment, development, and evaluation (GRADE).
Results
99 randomised clinical trials involving 6582 adults of varying health conditions (720 healthy, 5862 existing health conditions) were identified. All intermittent fasting and continuous energy restriction diet strategies reduced body weight when compared with ad-libitum diet. Compared with continuous energy restriction, alternate day fasting was the only form of intermittent fasting diet strategy to show benefit in body weight reduction (mean difference -1.29 kg (95% CI -1.99 to -0.59), moderate certainty of evidence). Additionally, alternate day fasting showed a trivial reduction in body weight compared with both time restricted eating and whole day fasting (mean difference -1.69 kg (-2.49 to -0.88) and -1.05 kg (-1.90 to -0.19), respectively, both with moderate certainty of evidence). Estimates were similar among trials with less than 24 weeks follow-up (n=76); however, moderate-to-long-term trials (≥24 weeks, n=17) only showed benefits in weight reduction in diet strategies compared with ad-libitum. Furthermore, in comparisons between intermittent fasting strategies, alternate day fasting lowered total cholesterol, triglycerides, and non-high density lipoprotein compared with time restricted eating. Compared with whole day fasting, however, time restricted eating resulted in a small increase in total cholesterol, low density lipoprotein cholesterol, and non-high density lipoprotein cholesterol. No differences were noted between intermittent fasting, continuous energy restriction, and ad-libitum diets for HbA1c and high density lipoprotein.
Conclusions
Minor differences were noted between some intermittent fasting diets and continuous energy restriction, with some benefit of weight loss with alternate day fasting in shorter duration trials. The current evidence provides some indication that intermittent fasting diets have similar benefits to continuous energy restriction for weight loss and cardiometabolic risk factors. Longer duration trials are needed to further substantiate these findings.
Trial registration
ClinicalTrials.gov NCT05309057.
Abstract via Europe PMC. Copyright remains with the authors or publisher (CC BY-NC).
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