Low Carbohydrate Versus Isoenergetic Balanced Diets for Reducing Weight and Cardiovascular Risk: A Systematic Review and Meta-Analysis

PLoS One. 2014 Jul 9;9(7):e100652. doi: 10.1371/journal.pone.0100652. eCollection 2014.

Abstract

Background: Some popular weight loss diets restricting carbohydrates (CHO) claim to be more effective, and have additional health benefits in preventing cardiovascular disease compared to balanced weight loss diets.

Methods and findings: We compared the effects of low CHO and isoenergetic balanced weight loss diets in overweight and obese adults assessed in randomised controlled trials (minimum follow-up of 12 weeks), and summarised the effects on weight, as well as cardiovascular and diabetes risk. Dietary criteria were derived from existing macronutrient recommendations. We searched Medline, EMBASE and CENTRAL (19 March 2014). Analysis was stratified by outcomes at 3-6 months and 1-2 years, and participants with diabetes were analysed separately. We evaluated dietary adherence and used GRADE to assess the quality of evidence. We calculated mean differences (MD) and performed random-effects meta-analysis. Nineteen trials were included (n = 3209); 3 had adequate allocation concealment. In non-diabetic participants, our analysis showed little or no difference in mean weight loss in the two groups at 3-6 months (MD 0.74 kg, 95%CI -1.49 to 0.01 kg; I2 = 53%; n = 1745, 14 trials; moderate quality evidence) and 1-2 years (MD 0.48 kg, 95%CI -1.44 kg to 0.49 kg; I2 = 12%; n = 1025; 7 trials, moderate quality evidence). Furthermore, little or no difference was detected at 3-6 months and 1-2 years for blood pressure, LDL, HDL and total cholesterol, triglycerides and fasting blood glucose (>914 participants). In diabetic participants, findings showed a similar pattern.

Conclusions: Trials show weight loss in the short-term irrespective of whether the diet is low CHO or balanced. There is probably little or no difference in weight loss and changes in cardiovascular risk factors up to two years of follow-up when overweight and obese adults, with or without type 2 diabetes, are randomised to low CHO diets and isoenergetic balanced weight loss diets.

Publication types

  • Comparative Study
  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Review
  • Systematic Review

MeSH terms

  • Cardiovascular Diseases / diet therapy*
  • Cardiovascular Diseases / prevention & control
  • Diabetes Mellitus, Type 2 / diet therapy
  • Diet, Carbohydrate-Restricted*
  • Diet, Reducing*
  • Energy Intake
  • Humans
  • Obesity / diet therapy*
  • Patient Compliance
  • Randomized Controlled Trials as Topic
  • Risk Factors
  • Treatment Outcome
  • Weight Loss

Grant support

This review was funded by the Effective Health Care Research Consortium and the South African Medical Research Council. CN is funded by the Centre for Evidence-based Health Care (CEBHC) and the South African Medical Research Council. AS and TY are funded by CEBHC. MS is funded by University of Cape Town. JV is funded by Stellenbosch University and the South African Cochrane Centre. PG is funded by the University of Liverpool and the Evidence Building and Synthesis Research Consortium. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.