One-year comparison of a high-monounsaturated fat diet with a high-carbohydrate diet in type 2 diabetes.

OBJECTIVE: The purpose of this study was to compare the effects of high-monounsaturated fatty acid (MUFA) and high-carbohydrate (CHO) diets on body weight and glycemic control in men and women with type 2 diabetes. RESEARCH DESIGN AND METHODS: Overweight/obese participants with type 2 diabetes (n = 124, age = 56.5 +/- 0.8 years, BMI = 35.9 +/- 0.3 kg/m2, and A1C = 7.3 +/- 0.1%) were randomly assigned to 1 year of a high-MUFA or high-CHO diet. Anthropometric and metabolic parameters were assessed at baseline and after 4, 8, and 12 months of dieting. RESULTS: Baseline characteristics were similar between the treatment groups. The overall retention rate for 1 year was 77% (69% for the high-MUFA group and 84% for the high-CHO group; P = 0.06). Based on food records, both groups had similar energy intake but a significant difference in MUFA intake. Both groups had similar weight loss over 1 year (-4.0 +/- 0.8 vs. -3.8 +/- 0.6 kg) and comparable improvement in body fat, waist circumference, diastolic blood pressure, HDL cholesterol, A1C, and fasting glucose and insulin. There were no differences in these parameters between the groups. A follow-up assessment of a subset of participants (n = 36) was conducted 18 months after completion of the 52-week diet. These participants maintained their weight loss and A1C during the follow-up period. CONCLUSIONS: In individuals with type 2 diabetes, high-MUFA diets are an alternative to conventional lower-fat, high-CHO diets with comparable beneficial effects on body weight, body composition, cardiovascular risk factors, and glycemic control.

The role of energy expenditure in the differential weight loss in obese women on low-fat and low-carbohydrate diets.

We have recently reported that obese women randomized to a low-carbohydrate diet lost more than twice as much weight as those following a low-fat diet over 6 months. The difference in weight loss was not explained by differences in energy intake because women on the two diets reported similar daily energy consumption. We hypothesized that chronic ingestion of a low-carbohydrate diet increases energy expenditure relative to a low-fat diet and that this accounts for the differential weight loss. To study this question, 50 healthy, moderately obese (body mass index, 33.2 +/- 0.28 kg/m(2)) women were randomized to 4 months of an ad libitum low-carbohydrate diet or an energy-restricted, low-fat diet. Resting energy expenditure (REE) was measured by indirect calorimetry at baseline, 2 months, and 4 months. Physical activity was estimated by pedometers. The thermic effect of food (TEF) in response to low-fat and low-carbohydrate breakfasts was assessed over 5 h in a subset of subjects. Forty women completed the trial. The low-carbohydrate group lost more weight (9.79 +/- 0.71 vs. 6.14 +/- 0.91 kg; P < 0.05) and more body fat (6.20 +/- 0.67 vs. 3.23 +/- 0.67 kg; P < 0.05) than the low-fat group. There were no differences in energy intake between the diet groups as reported on 3-d food records at the conclusion of the study (1422 +/- 73 vs. 1530 +/- 102 kcal; 5954 +/- 306 vs. 6406 +/- 427 kJ). Mean REE in the two groups was comparable at baseline, decreased with weight loss, and did not differ at 2 or 4 months. The low-fat meal caused a greater 5-h increase in TEF than did the low-carbohydrate meal (53 +/- 9 vs. 31 +/- 5 kcal; 222 +/- 38 vs. 130 +/- 21 kJ; P = 0.017). Estimates of physical activity were stable in the dieters during the study and did not differ between groups. These results confirm that short-term weight loss is greater in obese women on a low-carbohydrate diet than in those on a low-fat diet even when reported food intake is similar. The differential weight loss is not explained by differences in REE, TEF, or physical activity and likely reflects underreporting of food consumption by the low-fat dieters.