MCT’s Enhance Weight Loss Only When Replaced with Other Fats.

Fats varying in fatty acid chain lengths are metabolized differently. Medium-chain triglycerides (MCT), containing 6–12 carbon fatty acids. MCTs are naturally found in foods such as coconut oil, palm oil, and butter. Coconut oil has the highest naturally occurring percentage of MCTs, which compose nearly 60% of its total fat content. The vast majority of the fats and oils eaten by Americans are saturated or unsaturated or come from an animal or a plant, are composed of long-chain triglycerides (LCT). Probably 98 to 100% of all the fats we eat consist of LCT. LCT are absorbed directly into the portal circulation and transported to the liver for rapid oxidation. LCT, however, are transported via chylomicrons into the lymphatic system, allowing for extensive uptake into adipose tissue. Therefore, it has been hypothesized that the rapid metabolism of MCT may increase energy expenditure (EE), decrease their deposition into adipose tissue and result in faster satiety.

There is evidence to suggest that short-term consumption of MCT increases energy expenditure in humans and results in decreased fat cell size and body weight accretion in animals. Medium chain fatty acids (MCFA) are readily oxidized in the liver. Animal and human studies have shown that the fast rate of oxidation of MCFA leads to greater energy expenditure (EE). Most animal studies have also demonstrated that the greater EE with MCFA relative to long-chain fatty acids (LCFA) results in less body weight gain and decreased size of fat depots after several months of consumption. Furthermore, both animal and human trials suggest a greater satiating effect of medium-chain triglycerides (MCT) compared with long-chain triglycerides (LCT). However, results from human intervention studies investigating the weight reducing potential of MCTs, have been mixed.

Researchers just published a systematic review and meta-analysis of randomized controlled trials comparing the effects of MCTs to long-chain triglycerides (LCTs) on weight loss and body composition in adults. Changes in blood lipid levels were secondary outcomes. 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. Thirteen trials (n=749) were identified. Compared with LCTs, MCTs decreased body weight); waist circumference, hip circumference, total body fat; total subcutaneous fat, and visceral fat. No differences were seen in blood lipid levels. 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. MCT’s can be used for safe and effective weight loss if you replace LCT with MCT’s in your diet, but don’t be fooled into thinking that MCT’s are a wonder fat that magically makes fat shrink. Only by replacing LCT with MCT’s has it been shown to reduce bodyweight and enhance fat loss.  Bodybuilders may want to consider experimenting with MCT’s for fat loss.
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References:

Scalfi, L, Coltorti, A. & Contaldo, F. (1991) Postprandial thermogenesis in lean and obese subjects after meals supplemented with medium-chain and long-chain triglycerides. Am. J. Clin. Nutr. 53:1130-1133.

Seaton, T. B., Welle, S. L, Warenko, M. K. & Campbell, R. G. (1986) Thermic effect of medium-chain and long-chain triglycerides in man. Am. J. Clin. Nutr. 44:630-634.

Hill, J. O., Peters, J. C., Yang, D., Sharp, T., Kaler, M., Abumrad, N. N. & Greene, H. L. (1989) Thermogenesis in humans during overfeeding with medium-chain triglycerides. Metabolism 38:641-648.

Rothwell, N. J. & Stock, M. J. (1987) Stimulation of thermogenesis and brown fat activity in rats fed medium chain triglyceride. Metabolism 36:128-130.

Van Wymelbeke, V., Himaya, A., Louis-Sylvestre, J. & Fantino, M. (1998) Influence of medium-chain and long-chain triacylglycerols on the control of food intake in men. Am. J. Clin. Nutr. 68:226-234.

Mumme K, Stonehouse W. Effects of medium-chain triglycerides on weight loss and body composition: a meta-analysis of randomized controlled trials. J Acad Nutr Diet. 2015 Feb;115(2):249-63.

Robbie Durand has been in the sports supplement and  bodybuilding industry for 15 years. He has contributed to many national magazines and web sites. He has an M.A. in exercise physiology from Southeastern University and a B.A. in Dietetics from Louisiana State University.