The effect of exercise and the alteration of carbohydrate content of a hypocaloric diet on blood lipids
Twelve obese young women (aged 22-36) were studied to determine the·effects of the combination of an exercise program with either a high carbohydrate (HC) hypocaloric diet or low carbohydrate (LC) hypocaloric diet on total cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides. Subjects were randomly placed in one of the diet groups (530 kcal/day) and participated in submaximal (60% VO₂ max) exercise sessions three times per week for a period of 28 days. After the treatment period, the subjects consumed a 1000 kcal/day mixed diet for one week while continuing the exercise program. Blood samples were drawn weekly for the analysis of total cholesterol, HDL cholesterol and triglycerides. Weight significantly decreased in both groups (mean decrease = 9.8% for LC; 8.8% for HC). After week one of the diet, total cholesterol and HDL cholesterol decreased significantly throughout the rest of the study. Due to the changes in total cholesterol, the total cholesterol/HDL cholesterol ratio decreased throughout the study, reaching significance by the post-treatment period when the ratio was 20.6% below baseline levels for both groups. There were no significant changes in triglycerides for either group. However, triglycerides increased throughout the dietary treatment (mean increase 9.5% for LC; 18.7% for HC). Triglyceride concentrations also changed during the post-treatment week as the LC group had a mean decrease of 38.3% and HC group, 8.2% from baseline values. These data suggest that both diets are equally effective in reducing body weight in young women. Also, in spite of the decreases noted in HDL cholesterol in both groups, total cholesterol decreased even further, thus producing a lower, more favorable total cholesterol/HDL cholesterol ratio.