Predicted and measured resting energy expenditure in healthy young women.

Basal energy expenditure (BEE) was either measured by indirect calorimetry or predicted by different formulae in 104 young women: 74 lean and overweight subjects (normal weight, NWt) and 30 obese subjects. The predictive equations were based on weight alone (Owen, FAO-1, Schofield-1) or on weight and height (Harris-Benedict, Mifflin, Kleiber, and again FAO-2 and Schofield-2). With the exception of the Owen equation all the equations over-estimated measured BEE in both study groups. The ratio between measured and predicted value (% MP) varied between 102.3 (Owen) and 87.7 (Kleiber) in the NWt subjects and between 113.2 (Owen) and 89.3 (Schofield-1) in the obese subjects. The range including 95% of the predicted-measured differences (PMdiff) was larger than 1700 kJ/d in the NWt group and 2300 kJ/d in the obese group. In both study groups most of the equations showed a significant relationship between PMdiff and/or % MP with body weight and the magnitude of BEE. In conclusion, these equations are of little help in predicting BEE in a single subject and should be used with caution when assessing energy requirements in populations or groups of subjects.

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.

Bioimpedance analysis and resting energy expenditure in undernourished and refed anorectic patients.

Anthropometry, bioimpedance analysis (BIA) and resting energy expenditure (REE) were evaluated in young female patients affected by anorexia nervosa who were either severely malnourished (MnA) or already refed (RfA) and in a control group of healthy young women (WnC). Fat-free mass (FFM) and fat mass (FM), evaluated from skinfold thickness, were severely decreased in the MnA group while they were very similar in the RfA group and in the WnC group. With respect to BIA parameters, impedance (Z) was significantly higher in absolute terms in the MnA but lower than in the other groups when expressed as specific impedance, i.e. after normalization for both FFM and height. Phase angle significantly differed between the three groups, being significantly (P < 0.01) lower in the MnA (3.70 +/- 0.83 degrees) and the RfA (4.36 +/- 0.82) than in the WnC (5.17 +/- 0.40). REE was comparable in RfA subjects and WnC subjects, while it was sharply decreased (P < 0.01) in the MnA patients both in absolute value and after adjustment for body composition (FFM and FM) or body weight. This cross-sectional study shows that marked changes in BIA parameters occur in undernourished anorectic patients and also in the anorectic subjects who were previously very underweight but studied only after having already regained a normal body size. REE was deeply decreased in the undernourished anorectic women even when the differences in body composition or Wt were taken into account, indicating the occurrence of a significant adaptation of energy expenditure to chronic underfeeding.

Postprandial thermogenesis in leanness and anorexia nervosa.

Resting energy expenditure (REE) and postprandial thermogenesis (PPT) after the ingestion of a mixed test meal (3.56 MJ, 850 kcal) were determined in 7 anorectic patients, 7 very lean women and 8 control women. REE is absolute value was sharply decreased in the anorectics, but did not significantly differ between the very lean and the control subjects. On the other hand, when adjusted for body weight, REE only tended (p = 0.18) to be lower in the anorectics in comparison to the control women. PPT was similar in the anorectics (187.2 +/- 24.6 kJ/4 h) and the controls (200.7 +/- 16.8 kJ/4 h), but lower in the lean subjects (137.5 +/- 20.0 kJ/4h: p less than 0.05) than in the other two groups. The present study shows that the thermic response to the ingestion of a mixed test meal was not decreased in undernourished anorectic patients whereas it was significantly reduced in very lean healthy women.

Postprandial thermogenesis in lean and obese subjects after meals supplemented with medium-chain and long-chain triglycerides.

The thermic effect of medium-chain triglycerides (MCTs) was studied in six lean and six obese young males by evaluating postprandial thermogenesis (PPT) after the ingestion of mixed meals containing either 38 g long-chain triglycerides (LCTs) or 30 g MCTs plus 8 g LCTs. Postabsorptive resting metabolic rate (RMR) was higher (P less than 0.05) in the obese individuals than in the lean ones. PPT, evaluated as 6-h incremental areas above RMR, was greater (P less than 0.05) in both groups after meals containing MCTs. The thermic effect of MCTs was 119.7 +/- 33.9 and 144.7 +/- 48.8 kJ/6 h in the lean and the obese subjects, respectively. The postprandial response of glucose, insulin, and free fatty acids did not depend on the type of oil contained in the meal. Our study shows that PPT is enhanced in both lean and obese subjects when LCTs in a mixed meal are replaced with MCTs.

[Validity of 5 bioelectric impedance equations for the estimation of lean body mass in women]. / Validità di cinque equazioni dell'impedenziometria bioelettrica per la stima della massa corporea magra nella donna.

Fat free mass (FFM) predicted by five bioelectrical impedance (BIA) available formulae (Segal et al., Lukaski et al., Kushner et al., Deurenberg et al., manufacturer's predictive equation) was compared with densitometrically-determined FFM (as a reference method) in two groups of young women with different anthropometric characteristics. In the farmers (very short and light individuals), none of the studied formulae was able to accurately predict FFM: this latter was overestimated in subjects with low and underestimated in those with high FFM. In the other group (INCAP employees), only values predicted by Lukaski formula were in perfect agreement with FFM, showing no bias depending on FFM changes. In conclusion, the available BIA formulae seem to be specific for population from which they were derived and could not be used on samples from other populations if not cross-validated.

[Basal metabolism and postprandial thermogenesis in anorexia nervosa and constitutional leanness]. / Metabolismo basale e termogenesi postprandiale nell'anoressia nervosa e nella magrezza costituzionale.

Body composition and energy expenditure (basal metabolic rate--BMR--and postprandial thermogenesis--PPT) were evaluated in 11 anorectic patients, 16 very lean young women and 26 control female subjects. BMR in absolute terms was severely depressed in the anorectics when compared to the other two groups (p less than 0.01). After adjustment for fat free mass BMR was significantly higher in the lean subjects than the controls (p less than 0.05). PTT was studied for 240 minutes after the ingestion of a 3.56 MJ mixed meal (16% Prot, 50% CHO and 34% Fat) in 7 anorectics, 7 lean and 8 control women. PPT was similar in the anorectics and in the controls, but lower in the lean subjects (p less than 0.05) than in the other two groups. This study shows that a sharp decline in BMR occurs in severely undernourished anorectic patients who, however, have a normal PPT. On the other hand, very lean healthy women tend to have higher BMR but a decreased thermic response to a mixed test meal.

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)

Reduced regulatory thermogenesis in pregnant and ovariectomized women.

Diet-induced thermogenesis has been evaluated in five ovariectomized young women, five late pregnant (at the 8th month of pregnancy) and five age matched lean control women. Post-prandial thermogenesis was tested after a 900 Kcal mixed meal. Although pregnant (p less than 0.05) and ovariectomized showed a basal metabolic rate higher than control females, both groups had a significantly lower post-prandial thermogenesis when compared to the lean one (p less than 0.05). It is concluded that post-prandial thermogenesis is depressed in pregnant and ovariectomized females and that this condition may facilitate, at least in predisposed adult women, the development of obesity.

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.

Reduced cold-induced thermogenesis in familial human obesity.

It is well known that cold and diet-induced thermogenesis, which is mediated in small rodents by the hypothalamic-noradrenergic fibers-brown adipose tissue axis, is impaired in genetically obese mice. To test whether these adaptive mechanisms are also impaired in obese humans, 12 young males who were otherwise healthy (6 lean and 6 obese) were examined. The obese subjects had an early-onset type of obesity with a strong family history of it as well. Deep body temperature was measured by using a deep body thermometer furnished with three thermocouples. They were respectively placed on the sternum, on the interscapular area immediately under the neck (HIS), and on the 4th intercostal space (LIS) in order to study core temperature as well as heat production where brown adipose tissue could also be present in adults. Both lean and obese subjects were kept in a thermoneutral environment (28 degrees C) until they reached a steady-state body temperature and then rapidly transferred into a cold room (6-8 degrees C) where they remained up to 60 min. Body temperature decreased in both groups, but the decrease was more marked in the obese individuals on the sternum (P less than 0.01), on HIS (P less than 0.05) and on LIS (P less than 0.05) when compared to lean individuals. In conclusion, cold-induced thermogenesis is impaired in familial early-onset human obesity and in genetically obese mice.

Post prandial thermogenesis in different pathophysiological conditions.

Post Prandial Thermogenesis (PPT) is defined as the net increase in energy expenditure following the ingestion of a meal whereas diet-induced thermogenesis (DIT) indicates the overall influence of nutrients on energy expenditure. This paper reviews available data on PPT under specific clinical and dietetic conditions, e.g. the findings on PPT from pregnant and ovariectomized women, for elderly people, or the effects after MCT or LCT supplemented meals. PPT can be considered a suitable method to evaluate possible abnormalities of regulatory thermogenesis under certain clinical conditions and for the study of the acute effects of dietary components on energy expenditure.