Low-carb vs low-fat diets: meta-analysis | Br J Nutr

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Takeaway

  • Low-carbohydrate diets yielded greater weight loss, whereas low-fat diets yielded a smaller increase in LDL cholesterol levels.

Key Results

  • Relative to peers on low-fats diets, participants on low-carb diets lost more weight (weighted mean difference, –2.17 kg; 95% CI, –3.36 to –0.99), had a greater reduction in triglyceride levels (–0.26 mmol/L; –0.37 to –0.15), and had a greater increase in HDL cholesterol levels (0.14 mmol/L; 0.09 to 0.19).
  • However, the low-carb diet group also had a greater increase in levels of LDL cholesterol (weighted mean difference, 0.16 mmol/L; 95% CI, 0.003 to 0.33).
  • There were no significant differences between diets with respect to changes in total cholesterol, systolic or diastolic blood pressure, and glucose or insulin levels.

Study Design

  • A meta-analysis of 11 randomized controlled trials having a total of 1,369 healthy overweight participants and an intervention period of at least 6 months.
  • The main outcomes were weight loss and changes in cardiovascular risk indicators.

Limitations

  • There was moderate to high heterogeneity in the trial variables assessed.
  • Findings may have been influenced by publication bias.
  • The trials used different support systems.
  • Some trials found drift in participants' diets over time.
  • Findings may not apply to individuals with obesity-related comorbidities.

Why this matters

  • The greater weight loss with low-carb diets should be balanced against the greater increase in LDL cholesterol levels.