What do they do? Medium chain triglycerides (MCT) are a class of fatty acids. Their chemical composition is of a shorter length than the long-chain fatty acids present in most other fats and oils, which accounts for their name. They are also different from other fats in that they have a slightly lower calorie content1 and they are more rapidly absorbed and burned as energy, resembling carbohydrate more than fat
MCT have been shown to increase calorie burning compared with other fats
Some short-term studies have shown that MCT lowers blood glucose levels
Body builders have always searched for a supplement that will increase metabolic rate, reduce body fat and preserve muscle mass. This is especially important one week prior to a contest when calorie intake is decreased in an effort to reduce body fat to the lowest level possible without breaking down muscle protein. Despite the frequent claims for the benefits of MCTs in bodybuilding, there are no published scientific studies that have examined MCT use by body builders. The claims for MCTs are based on individual scientific studies that look at the use of MCTs in non-athletic populations. For example, a 1986 study found that the metabolic rate of seven healthy men increased by 12% with MCT ingestion versus only 4% with long chain fats. The authors speculated that weight loss would occur if MCTs were substituted for long chain fats and total calories remained the same. However, the rise in metabolic rate is small and the substitution of MCTs for long chain fats would have to be substantial for weight loss to be achieved.