Reduction of plasma catecholamines in humans during clinically controlled severe underfeeding.

BACKGROUND: Sympathetic hyperactivity is one factor for alterations encountered in the plurimetabolic syndrome, a cluster of metabolic abnormalities including obesity, hyperlipidemia, sometimes hyperglycaemia, and hypertonia. It was interesting to know if prolonged severe underfeeding (230 kcal/day) leads to decreases in catecholamines in those patients. METHODS: The plasma concentrations of catecholamines in patients (n = 16) suffering from plurimetabolic syndrome were studied before and during a 16-day period of medically controlled severe underfeeding (230 kcal/day) at rest and in response to exercise. RESULTS: During the period of underfeeding, mean norepinephrine concentrations decreased at rest from 1.45 to 0. 96 nmol/liter, and in response to exercise, from 6.1 to 3.2 nmol/liter. Epinephrine concentrations decreased from 0.15 to 0.1 nmol/liter and from 0.26 to 0.17 nmol/liter, respectively. A significant decrease in catecholamine concentrations was observed only after 16 days of underfeeding. CONCLUSIONS: Clinically controlled underfeeding of patients with plurimetabolic syndrome may result in beneficial clinical and biochemical effects. The findings indicate that relatively long periods of underfeeding induce decreases in plasma catecholamine concentrations. Nevertheless, most of the fall in mean values in norepinephrine and also of the fall in blood pressure values occurred by Day 2. From those tendencies and from the significant changes in both parameters at Day 16 of severe underfeeding one could conclude that altered sympathetic nervous system activity could contribute to the fall in blood pressure.

Diet-induced thermogenesis in man: thermic effects of single protein and carbohydrate test meals in lean and obese subjects.

Postprandial thermogenesis of 8 healthy males of normal body weight and 17 healthy obese subjects with a body weight gain of more than 10 kg per year was measured continuously by means of a respiratory chamber over 10 h after test meals of 1 and 2 MJ protein (casein) and 2 MJ carbohydrate (hydrolized starch). The total thermic response to all test meals was reduced by about 50% in the obese subjects. The thermic response was related to body weight, energy intake, resting metabolic rate and weight loss during restricted energy intake. The necessity for a careful characterization of the obese subjects in studies of thermogenesis and of efficiency of energy utilization in obesity is pointed out. It is suggested that thermic response to food can be considered as a suitable indicator for the distinction between people of different metabolic efficiency.

Diet-induced thermogenesis in man: thermic effects of single proteins, carbohydrates and fats depending on their energy amount.

The diet-induced thermogenesis of 12 healthy males of normal body weight was measured by means of indirect calorimetry over 6 h after test meals of 1, 2 or 4 MJ protein (white egg, gelatin, casein), carbohydrate (starch, hydrolyzed starch) or fat (sunflower oil, butter). The totals of the thermic responses proved to be dependent on the type of nutrient supplied as much as on its quantity. The effect of 1 MJ protein was at least three times as large as that of an isocaloric carbohydrate supply. The investigated dietary fats produced no evident thermic response. The doubling of the energy intake of either casein or hydrolyzed starch led to the approximate doubling of the thermic effect.