Metabolic effects of carbohydrate in low-calorie diets

Fasting plasma glucose turnover, urinary 3-methylhistidine excretion, and fasting plasma protein profiles were compared in a 4-week randomized clinical trial of two very low-calorie weight-reduction diets. Diet A (360 kcal) provided 1.5 g egg protein per kg ideal body weight (IBW) but no carbohydrate. Diet B (340 kcal) provided 0.8 g egg protein per kg IBW plus 0.7 g carbohydrate per kg IBW. Eleven moderately obese healthy young women were studied. After 3 weeks of dieting, fasting plasma glucose appearance and oxidation decreased by equal amounts (20% and 30%, respectively) for both diets. 3-methylhistidine excretion remained at control rates for the first week on the diets, then fell by equal amounts (25% to 30%) with both diets. Similar declines were observed for both diets in serum prealbumin and retinol-binding protein concentrations. Mean serum transferrin declined with both diets, but the changes were not statistically significant. Serum albumin was unchanged by either diet. Thus, there were no significant differences between the two diets with regard to any of the measured parameters.