Effects of Medium-Chain Triglycerides on Weight Loss and Body Composition: A Meta-Analysis of Randomized Controlled Trials

Background Medium-chain triglycerides (MCTs) may result in negative energy balance and weight loss through increased energy expenditure and lipid oxidation. However, results from human intervention studies investigating the weight reducing potential of MCTs, have been mixed. Objective To conduct a systematic review and meta-analysis of randomized controlled trials comparing the effects of MCTs, specifically C8:0 and C10:0, to long-chain triglycerides (LCTs) on weight loss and body composition in adults. Changes in blood lipid levels were secondary outcomes. Methods Randomized controlled trials >3 weeks' duration conducted in healthy adults were identified searching Web of Knowledge, Discover, PubMed, Scopus, New Zealand Science, and Cochrane CENTRAL until March 2014 with no language restriction. Identified trials were assessed for bias. Mean differences were pooled and analyzed using inverse variance models with fixed effects. Heterogeneity between studies was calculated using I-2 statistic. An I-2>50% or P<0.10 indicated heterogeneity. Results Thirteen trials (n=749) were identified. Compared with LCTs, MCTs decreased body weight (-0.51 kg [95% CI -0.80 to -0.23 kg]; P<0.001; I-2=35%); waist circumference (-1.46 cm [95% CI -2.04 to -0.87 cm]; P<0.001; I-2=0%), hip circumference (-0.79 cm [95% CI -1.27 to -0.30 cm]; P=0.002; I-2=0%), total body fat (standard mean difference -0.39 [95% CI -0.57 to -0.22]; P<0.001; I-2=0%), total subcutaneous fat (standard mean difference -0.46 [95% CI -0.64 to -0.27]; P<0.001; I-2=20%), and visceral fat (standard mean difference -0.55 [95% CI -0.75 to -0.34]; P<0.001; I-2=0%). No differences were seen in blood lipid levels. Many trials lacked sufficient information for a complete quality assessment, and commercial bias was detected. Although heterogeneity was absent, study designs varied with regard to duration, dose, and control of energy intake. Conclusions Replacement of LCTs with MCTs in the diet could potentially induce modest reductions in body weight and composition without adversely affecting lipid profiles. However, further research is required by independent research groups using large, well-designed studies to confirm the efficacy of MCT and to determine the dosage needed for the management of a healthy body weight and composition.