Dexfenfluramine as an adjunct to a reduced-fat, ad libitum diet: effects on body composition, nutrient intake and cardiovascular risk factors.

OBJECTIVE

To investigate the specific effects of dexfenfluramine (dF) as an adjunct to a reduced-fat, ad libitum diet.

DESIGN

Double-blind, randomized, placebo-controlled study. Subjects were stabilized on the dietary program during a 12 w run-in period, and then were randomized to receive dF (15 mg) or placebo bd for an additional 12 w. One follow-up was conducted 12 w after cessation of treatment.

SUBJECTS

84 obese subjects (57 F; 27 M, mean body mass index = 34.7 +/- 3.2 kg/m2).

MEASUREMENTS

Body composition (by DEXA), fat distribution (by circumferences and DEXA), nutrient intake (by 7 d food diaries), blood lipids, blood glucose and blood pressure.

RESULTS

Mild side effects were reported by 19 dF subjects, and in seven subjects lethargy or dry mouth persisted for the 12 w of treatment. Relative to placebo, treatment with dF was associated with significantly greater reductions in body weight (-3.8 kg, 95% confidence interval [CI] = -4.9, -2.7), fat mass (-2.5 kg, 95% CI = -3.6, -1.4) and fat-free mass (-1.2 kg, 95% CI = 1.8, -0.7). Waist and hip circumferences also decreased (P < 0.01) but the waist:hip ratio remained unchanged. The ratio of waist:hip fat mass as measured by DEXA decreased more in the dF group (P < 0.01). Lower total energy intake (-439 kJ/d, 95% CI = -932, 54) and fat intake (-5.1 g/d, 95% CI = -10.8, 0.6) were also seen but were of borderline statistical significance. After adjusting for changes in fat intake, dF treatment was associated with lower cholesterol and triglyceride concentrations (P < 0.01). Twelve weeks following cessation of treatment, the rate of weight gain was not significantly different between the dF and the placebo groups (1.7 kg and 0.7 kg respectively), but the dF group remained significantly lighter than the placebo group (P < 0.01).

CONCLUSIONS

Dexfenfluramine treatment augments weight and fat loss on a reduced-fat, ad libitum diet, with some evidence for preferential loss of waist fat compared with hip fat. The decreases in total energy and fat intake with dF seem insufficient to explain the significant decreases in body weight and fat mass.