Meta-analysisindependent cross-checkabstract checked★ key study I-LIFE-102 in-depth review

Low-fat versus other diets for weight

Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis.

Overview

Tobias DK et al.. Lancet Diabetes Endocrinol 2015 · PMID 26527511 · DOI 10.1016/S2213-8587(15)00367-8

Over a year or more, low-fat diets did not cause more weight loss than other diets of similar intensity.

Does the study support the specific claim? Yes · Methodological quality: high

Study explained simply

What did the researchers want to find out?: Compare low-fat with other diets.
How was the study done?: Meta-analysis of 53 RCTs.
How many people, animals or samples were studied?: 68,128 adults.
What was actually found?: Low-fat not superior; low-carb slightly better in weight-loss trials.
How large was the observed effect?: 1.15 kg favouring low-carb.
What do the results mean in everyday life?: Total diet quality and energy matter more than fat share.
What are the study's limitations?: Heterogeneity.
What does it say about Elawady's specific claim?: Supports the claim.
Do the results apply to Germany and Europe?: Applies; same physiology.
What can explicitly not be concluded from this study?: Health effects beyond weight.

Authors: Tobias DK et al.
Journal: Lancet Diabetes Endocrinol
Year: 2015
Identifier: PMID 26527511 DOI 10.1016/S2213-8587(15)00367-8
Verification: verified – PubMed efetch 2026-10-26; Crossref update-to/updated-by check
Retracted: no
Corrections: none
Extent checked: abstract only
Conflicts of interest and funding: NIH and ADA funding; authors report no disclosures.

Do low-fat diets lead to more long-term weight loss than other diets?

Study design: Meta-analysis – Systematic review and random-effects meta-analysis of RCTs >=1 year
Population: Adults
Country: International
Period: Search to 31 Jul 2014
Sample size: 53 studies, 68,128 participants (69 comparisons)
Inclusion and exclusion criteria: not stated in abstract

Results: Weight-loss trials: low-carbohydrate > low-fat by 1.15 kg (0.52-1.79; I2 10%); low-fat vs other higher-fat interventions 0.36 kg (-0.66 to 1.37; I2 82%); low-fat better only vs usual diet (-5.41 kg, -7.29 to -3.54).
Absolute risks: not reported
Authors' conclusion: When compared with dietary interventions of similar intensity, RCT evidence does not support low-fat diets over other dietary interventions for long-term weight loss.

See stats/I-LIFE-101_fat_body_weight.py.

Cutting fat is not superior to other diets for weight loss - supports 'fat is not the origin of weight gain'.

Universal biology; applies in Europe and Egypt.

Supports the claim's core.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	high
Risk of bias	low
Precision of results	moderate
Directness	direct
Reproducibility	replicated
Consistency with the overall evidence	consistent
Regional transferability	high
Adequacy of the interpretation (by the archive)	not applicable