The aim of this randomized trial was to compare the effects of a behavioral intervention focusing on either calorie restriction alone or calorie plus fat restriction on weight loss and changes in lipids and glycemic control in individuals with non-insulin-dependent diabetes mellitus (NIDDM) or a family history of diabetes.
We recruited 44 obese women with NIDDM and 46 obese women with a family history of NIDDM and randomly assigned these subjects to calorie restriction (CAL) or to calorie plus fat restriction (CAL + FAT). All subjects participated in a 16-week behavioral weight loss program, with training in diet, exercise, and behavior modification. Subjects assigned to the CAL condition were given a 1,000−1,500 kcal/day goal and self-monitored calories consumed. Subjects assigned to the CAL + FAT condition had the same calorie goal, but were also given a fat goal (grams of fat/day), to produce a diet with < 20% of calories from fat; this group monitored both calories and fat grams.
Among NIDDM subjects, weight loss of the subjects in the CAL+FAT condition was significantly > subjects in the CAL condition (7.7 vs. 4.6 kg) and the CAL+FAT condition group also maintained their weight loss better at the 1-year follow-up (5.2 vs. 1.0 kg). Significant decreases in glucose, high-density lipoprotein (HDL) cholesterol, and total cholesterol were seen after 16 weeks of treatment among NIDDM subjects; these changes were similar in CAL and CAL+FAT groups, but a greater proportion of subjects in CAL condition required oral hypoglycemic medication. At the 1-year follow-up, all parameters had returned to baseline. No significant differences in weight loss or physiological changes were seen between CAL and CAL+FAT conditions in subjects with a family history of diabetes.
These results suggest that using the combination of calorie and fat restriction may help promote weight loss in obese NIDDM patients. No other long-term benefits of this regimen were observed.