Objective: The optimum diet composition for weight loss in obese women with or without previous gestational diabetes mellitus remains to be determined. Weight loss may be especially important for the latter group in terms of preventing future gestational as well as non-insulin dependent diabetes mellitus. We studied 40% vs. 55% carbohydrate calorically restricted diets to compare weight loss and metabolic response.
Methods: We performed a prospective, 12-week, blinded, randomized crossover study of 25 obese women; 13 of whom had previous gestational diabetes. Each woman was allocated to a treatment regimen for 6 weeks and then "crossed over" to the alternative regimen for an additional 6 weeks. Calories were provided in the form of nutritional supplement bars except for the evening meal that comprised 1/3 of the caloric needs. All subjects were seen and weighed weekly. Metabolic variables including glucose tolerance, glycated proteins, lipids, and percent body fat were measured at the beginning, crossover, and end of the study.
Results: Women with previous gestational diabetes mellitus were comparable to obese women without a history of previous gestational diabetes except that the former had higher maximum levels of glucose on a glucose tolerance test and higher fasting insulin levels consistent with greater insulin resistance. Weight loss was comparable for all groups during the first 6 weeks but attenuated in all groups during the second 6 weeks of the trial regardless of diabetes history or treatment group allocation. Women with or without a previous history of gestational diabetes had higher triglycerides while on a 55% carbohydrate diet than while on a 40% carbohydrate diet.
Conclusions: A weight loss regimen consisting of 40% carbohydrate results in lower triglyceride levels than those achieved with a 55% carbohydrate content diet in obese women. Thus, the hypocaloric diet with the higher fat content produced the more favorable lipid profile in all obese women.