Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials

• Published in: British journal of nutrition Vol. 115; no. 3; pp. 466 - 479
• Main Authors: Mansoor, Nadia, Vinknes, Kathrine J., Veierød, Marit B., Retterstøl, Kjetil
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 14.02.2016
• Subjects: Body Weight; Body weight loss; carbohydrate intake; Carbohydrates; Cardiovascular disease; Cardiovascular diseases; Cardiovascular Diseases - prevention & control; Cardiovascular system; Cholesterol; Cholesterol, HDL - blood; Cholesterol, LDL - blood; Criteria; Databases, Factual; Diabetes; Diet; Diet, Carbohydrate-Restricted; Diet, Fat-Restricted; Energy Intake; Evidence-based medicine; Health risks; High density lipoprotein; high density lipoprotein cholesterol; Human and Clinical Nutrition; Humans; Intervention; Low carbohydrate diet; Low density lipoprotein; low density lipoprotein cholesterol; Low fat diet; Meta-analysis; Mortality; Nutrient deficiency; Nutrition research; nutritional intervention; Obesity; Oils & fats; Randomization; randomized clinical trials; Randomized Controlled Trials as Topic; Risk analysis; Risk Factors; Triglycerides - blood; Weight control; Weight loss; Weight reduction; Low-carbohydrate diets; Low-fat diets; Cardiovascular risk factors; Weight loss; CHO carbohydrates; SBP systolic blood pressure; LC low CHO; LF low fat; DBP diastolic blood pressure; WMD weighted mean difference; RCT randomised controlled trials; TC total cholesterol
• ISSN: 0007-1145; 1475-2662; 1475-2662
• DOI: 10.1017/S0007114515004699

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.