High‐fat Medium‐chain Triglyceride Diet Attenuates Weight Gain, but Does Not Affect Insulin‐stimulated Glucose Uptake in Male Rats

Abstract

Recently, there has been increased dietary consumption of medium‐chain triglycerides (MCT; triglycerides containing fatty acids chains C6:0‐C12:0) for purported ergogenic and weight loss effects. Diets high in fat are known to contribute to insulin resistance, but the impact of high MCT‐based diets on glucose uptake and insulin signaling are not well‐known. Therefore, we investigated the effect of a high‐MCT diet on insulin‐stimulated glucose uptake in rat skeletal muscle. Male Sprague‐Dawley rats, ages 7–17 months, were assigned to one of 3 isocaloric dietary groups: 1) low‐fat control group (CON; 20% protein, 70% carbohydrate, 10% fat mostly from MCT), 2) high‐fat group (HF; 20% protein, 35% carbohydrate, 45% fat mostly from lard) and 3) high‐fat MCT group (MCT; 20% protein, 35% carbohydrate, 45% fat mostly from MCTs). All rats had ad libitum access to their respective diets and water for 8 weeks. Body masses and food consumption were recorded weekly. During the terminal study, a soleus muscle from eat rat was excised, split into equal thirds, and placed in vials containing physiological buffer including 1 of 3 insulin concentrations (0, 0.6, or 30nM). Muscles were then incubated in the presence of radioisotopes to determine glucose (2‐deoxyglucose; 2‐DG) uptake. Homogenates were also used for Western blotting to assess phosphorylation and abundance of key insulin signaling proteins. The MCT group consumed the least amount of food daily and gained the least weight at the end of 8wks. We observed a main effect of insulin (p<0.05) in regards to 2‐DG uptake, but no differences associated with diet. We found similar results regarding phospho‐AktSer473. We report that a high‐fat diet consisting of MCTs will lead to less weight gain compared to a high‐fat diet consisting of lard. However, the fat source did not affect insulin‐stimulated glucose uptake in isolated muscle, suggesting that diets high in MCTs may not improve insulin sensitivity compared to high lard‐based diets despite reduced weight gain. These results imply that a diet high in MCTs may translate to greater meal satiety and better weight maintenance, compared to other high‐fat and even lower‐fat diets.Support or Funding InformationOffice of Research and Graduate Studies and the Herbert H. & Grace A Dow College of Health Profession at Central Michigan UniversityThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.