The acute effect of dexfenfluramine on resting metabolic rate and postprandial thermogenesis in obese subjects: a double-blind placebo-controlled study.

The effects of dexfenfluramine (dFE: 30 mg per os) on energy expenditure were evaluated in seven young obese male subjects (mean +/- s.d.: age 30.9 +/- 6.1 years; BMI 39.8 +/- 4.4 kg/m2). Each subject was submitted, on a double-blind protocol and by random order, to four tests in which dFE or placebo (Pla) were administered either in the fasting state or in combination with a mixed test meal. Energy expenditure was measured by indirect calorimetry for 60 min before (BMR) and from 90 to 330 min after dFE or Pla. In those cases where the protocol required it, a mixed test meal (5 MJ, 1200 kcal; percentage of protein, carbohydrate and fat: 15, 55, and 30 respectively) was eaten 120 min after dFE or Pla. In the fasting state resting metabolic rate increased after dFE (mean +/- s.d.: 0.49 +/- 0.20 kJ/min) but not after Pla (-0.04 +/- 0.16 kJ/min) in comparison to BMR, the difference between the two tests being highly significant (P < 0.01). Post-prandial thermogenesis (over 3h) was also significantly higher after dFE than after Pla (232 +/- 85 kJ vs. 181 +/- 73 kJ; P < 0.025). On the other hand, dFE did not affect respiratory quotient (RQ), either in the fasting state or in the fed state. These results show that in obese subjects dFE increases energy expenditure in the post-absorptive state, as well as after the ingestion of food.

Short-term effects of moderate alcohol consumption on lipid metabolism and energy balance in normal men.

The short-term effects of moderate alcohol consumption on energy balance, serum lipids, and lipoproteins were studied in eight healthy middle-aged men (age 30 to 47 years and body mass index 23.1 to 27.7 w/h2). A crossover dietary trial included two isocaloric periods without (20% protein, 50% carbohydrate, 30% fat) or with alcohol (12% protein, 29% carbohydrate, 25% fat, 75 g of alcohol as red wine). Each period lasted 2 weeks. The body weight of the subjects remained stable over the study. Fasting blood glucose, serum insulin, total cholesterol, and LDL cholesterol were similar at the end of both dietary periods. Mean values of serum total triglyceride (108 +/- 18 v 85 +/- 24 mg/dL, P less than 0.05), VLDL-Tg (88 +/- 24 v 73 +/- 16 mg/dL, NS), and total HDL cholesterol (49.4 +/- 6.0 v 43.4 +/- 5.5 mg/dL, P less than 0.05) were higher after the diet with alcohol than without alcohol. The increase of HDL cholesterol was primarily due to that of HDL2 cholesterol (10.4 +/- 5.1 v 5.7 +/- 3.9 mg/dL, P less than 0.05). The concentration of apoprotein A-I, A-II, and B averaged 104 +/- 17 v 89 +/- 16 mg/dL, 33 +/- 4 v 28 +/- 8 mg/dL, P less than 0.02, and 111 +/- 24 v 105 +/- 33 mg/dL after the diets with and without alcohol, respectively. Adipose tissue LPL activity increased in six of the eight volunteers during the diet with alcohol. Resting metabolic rate, postprandial energy expenditure, and postprandial responses of blood glucose, serum insulin, triglyceride, and plasma FFA were similar after the both diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary fibre on postprandial thermogenesis.

The effect of fibre on postprandial thermogenesis was evaluated in seven healthy males (age 29.6 +/- 3.6 years, BMI 24.6 +/- 0.6 kg/m2) after they had ingested three isocaloric meals with different fibre contents: low fibre (Lfb) containing 8 g. dietary fibre; glucomannan (Glc), which was Lfb supplemented with 6 g glucomannan, a pectin-like fibre; and high fibre (Hfb) containing 26 g dietary fibre. Postprandial thermogenesis, evaluated for 6 h after the ingestion of food, was higher after the Lfb (82.3 +/- 5.4 kcal) than after the Hfb and Glc meals (69.4 +/- 6.8 and 61.4 +/- 8.4 kcal, respectively). Glucose and insulin responses were depressed over the first 2 h after the Hfb and Glc meals as compared to the Lfb meal. However, these differences disappeared when the whole 6 h postprandial period was considered. No major effects of the different fibre contents of the meals on postprandial triglyceride and FFA levels were detected. These results demonstrate that the fibre content of meals, besides the well known effect on energy intake, may also affect energy expenditure.