Effects of Low-Carbohydrate Diets v. Low-Fat Diets on Body Weight and Cardiovascular Risk Factors: A Meta-Analysis of Randomised Controlled Trials

Br J Nutr. 2016 Feb 14;115(3):466-79. doi: 10.1017/S0007114515004699.

Abstract

The effects of low-carbohydrate (LC) diets on body weight and cardiovascular risk are unclear, and previous studies have found varying results. Our aim was to conduct a meta-analysis of randomised controlled trials (RCT), assessing the effects of LC diets v. low-fat (LF) diets on weight loss and risk factors of CVD. Studies were identified by searching MEDLINE, Embase and Cochrane Trials. Studies had to fulfil the following criteria: a RCT; the LC diet was defined in accordance with the Atkins diet, or carbohydrate intake of <20% of total energy intake; twenty subjects or more per group; the subjects were previously healthy; and the dietary intervention had a duration of 6 months or longer. Results from individual studies were pooled as weighted mean difference (WMD) using a random effect model. In all, eleven RCT with 1369 participants met all the set eligibility criteria. Compared with participants on LF diets, participants on LC diets experienced a greater reduction in body weight (WMD -2·17 kg; 95% CI -3·36, -0·99) and TAG (WMD -0·26 mmol/l; 95% CI -0·37, -0·15), but a greater increase in HDL-cholesterol (WMD 0·14 mmol/l; 95% CI 0·09, 0·19) and LDL-cholesterol (WMD 0·16 mmol/l; 95% CI 0·003, 0·33). This meta-analysis demonstrates opposite change in two important cardiovascular risk factors on LC diets--greater weight loss and increased LDL-cholesterol. Our findings suggest that the beneficial changes of LC diets must be weighed against the possible detrimental effects of increased LDL-cholesterol.

Keywords: CHO carbohydrates; Cardiovascular risk factors; DBP diastolic blood pressure; LC low CHO; LF low fat; Low-carbohydrate diets; Low-fat diets; RCT randomised controlled trials; SBP systolic blood pressure; TC total cholesterol; WMD weighted mean difference; Weight loss.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Body Weight*
  • Cardiovascular Diseases / prevention & control*
  • Cholesterol, HDL / blood
  • Cholesterol, LDL / blood
  • Databases, Factual
  • Diet, Carbohydrate-Restricted*
  • Diet, Fat-Restricted*
  • Energy Intake
  • Humans
  • Randomized Controlled Trials as Topic
  • Risk Factors
  • Triglycerides / blood

Substances

  • Cholesterol, HDL
  • Cholesterol, LDL
  • Triglycerides