Relationship between overnight energy expenditure and BMR measured in a room-sized calorimeter

OBJECTIVE: The purpose of this study was to determine if overnight energy expenditure, the lowest energy expenditure sustained for 60 min during the night, measured and predicted basal metabolic rate are equivalent. DESIGN: Overnight energy expenditure (ON-EE), the lowest energy expenditure sustained for 60 min during sleep (LS-EE) and basal metabolic rate (BMR) were measured two to seven times in a room-sized indirect calorimeter in 69 adult subjects. Subjects' gender, age, weight and height were also used to predict BMR (FAO/WHO/UNU, 1985) (BMR-WHO). SETTING: Beltsville Human Nutrition Research Center, Beltsville, MD, USA. RESULTS: The results from calorimetry measurements (mean +/- s.d.) included: ON-EE (6.87 +/- 0.99 MJ/d), LS-EE (6.18 +/- 0.94 MJ/d) and BMR (6.87 +/- 0.99 MJ/d). Predicted BMR mean was: BMR-WHO, 6.95 +/- 1.03. The mean within-subject difference for the calorimetry measurements were: ON-EE, 0.21 MJ/d; LS-EE, 0.16 MJ/d; and BMR, 0.34 MJ/d. Results indicate there was no significant difference between ON-EE, BMR and BMR-WHO. LS-EE was significantly lower (P < 0.0001) than ON-EE, BMR and BMR-WHO. CONCLUSION: These results indicate that while metabolic rate drops significantly below BMR during sleep, overnight metabolic rate and BMR are equivalent.     

Interindividual variability in sleeping metabolic rate in Japanese subjects

INTRODUCTION: Basal metabolic rate (BMR) or sleeping metabolic rate (SMR) is the largest component of total energy expenditure (EE). An accurate prediction of BMR or SMR is needed to accurately predict total EE or physical activity EE for each individual. However, large variability in BMR and SMR has been reported. OBJECTIVES: This study was designed to develop prediction equations using body size measurements for the estimation of both SMR and BMR and to compare the prediction errors with those in previous reports. METHODS: We measured body size, height, weight and body composition (fat mass and fat-free mass) from skinfold thickness in adult Japanese men (n=71) and women (n=66). SMR was determined as the sum of EE during 8 h of sleep (SMR-8h) and minimum EE during 3 consecutive hours of sleep (SMR-3h) measured using two open-circuit indirect human calorimeters. BMR was determined using a human calorimeter or a mask and Douglas bag. RESULTS: The study population ranged widely in age. The SMR/BMR ratio was 1.01+/-0.09 (range 0.82-1.42) for SMR-8h and 0.94+/-0.07 (range 0.77-1.23) for SMR-3h. The prediction equations for SMR accounted for a 3-5% larger variance with 2-3% smaller standard error of estimate (SEE) than the prediction equations for BMR. DISCUSSION: SMR can be predicted more accurately than previously reported, which indicates that SMR interindividual variability is smaller than expected, at least for Japanese subjects. The prediction equations for SMR are preferable to those for BMR because the former exhibits a smaller prediction error than the latter.     

Energy expenditure at rest and during sleep in children with Prader-Willi syndrome is explained by body composition

BACKGROUND: Obesity in Prader-Willi syndrome (PWS) seems to be related to a low basal metabolic rate (BMR). In addition, abnormal sleep patterns reported in PWS might affect sleeping metabolic rate (SMR). OBJECTIVE: Our objective was to assess BMR and SMR adjusted for fat-free mass in young PWS patients. DESIGN: Subjects were 17 PWS patients (10 females and 7 males aged 7.5-19.8 y) and 17 obese control subjects matched for sex and bone age. SMR was measured in a respiratory chamber, BMR with a ventilated-hood system, and body composition by deuterium dilution. RESULTS: BMR and SMR were significantly lower in the PWS group than in the control group (5.36 +/- 1.18 and 4.62 +/- 1.08 MJ/d compared with 6.38 +/- 1.55 and 5.60 +/- 1.52 MJ/d, respectively; P < 0.05). When fat-free mass was included in the analysis, multiple regression showed no differences in BMR and SMR between groups. When weight was included in the analysis instead of fat-free mass, SMR was lower in the PWS group. Fat-free mass was lower in the PWS group both as an absolute value and when adjusted for height. CONCLUSION: BMR and SMR are low in young patients with PWS because of a low fat-free mass.     

The difference between the basal metabolic rate and the sleeping metabolic rate in Japanese

Previous studies have demonstrated the difference between the basal metabolic rate (BMR) and the sleeping metabolic rate (SMR): however, the difference in the Japanese population has not yet been explored. This study examined the relationship between the BMR and SMR in ninety-four healthy Japanese subjects (37 males and 57 females, 39 +/- 12 y of age and 22.0 +/- 7.4% body fat) in a respiratory chamber. The SMR was significantly lower than the BMR (1416 +/- 245 vs. 1492 +/- 256 kcal/d): however, there was a highly significant correlation between the two (r = 0.867; p < 0.001). The ratio of SMR/BMR largely varied among individuals (0.95 +/-0.08, 8.4% of the coefficient of variation). The ratio was significantly lower in males than in females (0.93 +/- 0.10 vs. 0.97 +/- 0.06, p < 0.05). None of the anthropometric measures (age, weight, body mass index, body surface area or percent body fat) correlated with the ratio. These results showed that SMR was 95%, of BMR on average in a healthy Japanese group. However, when applied over a longer time period (24 h or more), the difference tends to become negligible for most analyses in a group. Although the difference between SMR and BMR will induce a 5% gap of physical activity level defined as the total energy expenditure divided by the BMR or SMR, this factor seems to have little practical importance in epidemiological research.     

Body fat distribution and energy metabolism in obese men and women.

Upper body obesity seems to be associated with a better prognosis for weight loss than does lower body obesity. However, the impact of body fat distribution on energy metabolism is not clear.

One hundred fifteen non-diabetic obese Caucasians (64 males and 51 females) and 108 Caucasian lean controls (82 males and 26 females) were studied.

Body composition was assessed by hydrodensitometry and body fat distribution was estimated by the waist-to-thigh circumference ratio (W/T). Values of 24-hour energy expenditure (24h-EE), basal metabolic rate (BMR), sleeping metabolic rate (SMR) and respiratory quotient (RQ) were measured in a respiration chamber.

BMR, adjusted for differences in fat-free mass, fat mass, age and sex, correlated with W/T in obese males (r = 0.40; p < 0.01), but not in obese females. Obese male subjects with upper body obesity had BMR significantly higher than those with lower body obesity (2189 +/? 268 vs 1974 +/? 141 kcal/day; p < 0.01), independently of differences in fat-free mass, fat mass and age. No correlations were found between W/T and adjusted 24h-EE, SMR or RQ in all examined groups.

These findings indicate that in obese males, upper body obesity is associated with increased metabolic rate, possibly related to higher levels of lipid turnover in visceral fat.     

Basal metabolic rate as a proxy for overnight energy expenditure: the effect of age

Recommendations for daily energy requirements use factorial calculations based on BMR. Expressing total energy requirements as a multiple of BMR is based on the assumption that BMR is equal to overnight metabolic rate (OMR). The objective of the present study was to determine if BMR is an appropriate proxy for OMR in children, young adults and elderly. Data are presented of thirty children (11 (SD 2) years), thirty young adults (25 (SD 5) years) and fifty-nine elderly (61 (SD 5) years). OMR was measured in a respiration chamber while sleep was not hindered and BMR was measured directly afterwards with a ventilated hood system under strictly controlled conditions. The mean ratio of OMR:BMR was 0.92 (SD 0.09) for children, which was significantly different from 1.00 (P<0.001), 1.00 (SD 0.07) for young adults and 1.06 (SD 0.09) for elderly which was also different from 1.00 (P<0.001). For adults, BMR is an appropriate measure of OMR. In children, the use of BMR to estimate OMR would introduce an overestimate and for elderly an underestimate.     

The effect of exercise and improved physical fitness on basal metabolic rate

1. The suggestion that there is a sustained enhancement in metabolic rate after exercise was investigated during the course of a study in which six normal-weight volunteers (three men, three women) took part in a 9-week training programme. Baseline values were assessed in a 3-5 week control period of minimal activity before training. At the end of the study the subjects were capable of running for 1 h/d, 5 d/week. 2. Throughout the entire study the subjects were maintained on a constant diet. Measurement of energy expenditure by the doubly-labelled water (2H2(18)O) method showed that the subjects had an energy imbalance of +3% in the control and -20% at the end of the training period. The subjects were in positive (1.1 (SE 0.2) g) nitrogen balance in the second week of the control, and in negative (-0.6 (SE 0.3) g) N balance in the last week of the exercise period. 3. Over the course of the study maximum oxygen consumption (VO2max) and high-density-lipoprotein-cholesterol levels increased by 30%. Heart rate at rest and when performing a standard step test fell significantly. 4. Body composition was assessed weekly by 40K counting and skinfold thickness measurements, in addition to 2H2 dilution at the beginning and end of the study. Fat-free mass was apparently gained in the early phases of the study, but there was lack of agreement between the different methods of assessing body composition. Changes in body-weight were not significant. 5. Basal metabolic rate (BMR), overnight metabolic rate (OMR) and sleeping metabolic rate (SMR) were measured on three occasions: in the control period, and the beginning and end of the training periods. Average BMR in the control period was 5.91 (SE 0.39) MJ/24 h and was not changed with activity. There were no changes in OMR (5.71 (SE 0.27) MJ/24 h in the control) nor in SMR (5.18 (SE 0.27) MJ/24 h in the control), nor in BMR, OMR or SMR when expressed per kg body-weight, or per kg fat-free mass. 6. These results do not support the suggestions that there is a sustained increase in BMR following exercise that can usefully assist in weight-loss programmes.     

Lower metabolic rates of post-obese versus lean women: thermogenesis, basal metabolic rate and genetics

Components of daily metabolic rate (thermogenesis, BMR and net exercise) were compared between 16 women predisposed to obesity (post-obese) and 16 naturally lean controls of matching age, weight and height, at three levels of activity, in a whole-body respirometer. At all levels of activity, the mean metabolic rate of the post-obese was 15 per cent lower than that of the lean controls. Expenditure on net exercise showed the same relationship, but BMR was only 10 per cent lower, while thermogenesis was 50 per cent lower. The latter was partly due to the smaller food intake of the post-obese and also to a lower thermogenic response. In absolute terms BMR accounted for less than half of the difference in total energy expenditure between the post-obese and the lean (45 per cent). Thermogenesis accounted for approximately 40 per cent of the difference, and 15 per cent after adjusting for the different energy intakes. Significantly more post-obese subjects had a family history of obesity (88 per cent) than lean subjects (38 per cent). Within the post-obese and lean groups there was a consistent trend at each level of activity for those with a family history to have lower metabolic rates, indicating that family history of obesity has an influence on energy expenditure over and above personal history of obesity.     

Metabolic rate during and after aerobic exercise in post-obese and lean women

The effect of aerobic exercise (cycling on bicycle ergometer for four 10-min periods/60-80 per cent max VO2) on energy expenditure following the activity was investigated in 16 post-obese and 16 lean control women over 24 h and shorter periods. In addition, net energy expenditure during aerobic exercise was compared to that during prolonged mild activity (stepping for four 30-min periods at 12 steps/min). The measurements were made in a room respirometer. Aerobic exercise did not significantly stimulate the 24-h resting metabolic rate of either the post-obese (3 per cent, 50 kcal) or lean controls (2 per cent, 30 kcal), nor was there any significant stimulation over shorter periods: during waking hours RMR was non-significantly increased by 5 per cent in both the post-obese and lean controls. Sleeping expenditure remained the same in the post-obese and was decreased by 2 per cent in the lean controls. All subjects found the aerobic exercise to be quite uncomfortable, yet in both groups the net cost was smaller than that of prolonged mild exercise which was found to be acceptable (post-obese: aerobic 180 kcal, mild 250 kcal; lean controls: 220 kcal, 290 kcal). It is suggested that prolonged mild activity (eg, as in walking frequently) is more appropriate in increasing energy expenditure as a means of preventing or controlling obesity. Total expenditure at each level of activity is also expressed as multiples of BMR calculated from FAO/WHO/UNU (1985) prediction equations and from measured sleep values. The results show that the equations overestimated BMR in the post-obese.     

Effects of familial predisposition to obesity on energy expenditure in multiethnic prepubertal girls

BACKGROUND: The prevalence of childhood obesity is increasing and the causes of this are unknown. OBJECTIVE: The objective of this study was to determine whether energy expenditure (EE), measured by 24-h calorimetry and doubly labeled water, differed in normal-weight-for-height, multiethnic prepubertal girls with or without a familial predisposition to obesity. DESIGN: Normal-weight, prepubertal white (n = 52), African American (n = 30), and Hispanic (n = 19) girls with a mean (+/-SD) age of 8.5 +/- 0.4 y were studied according to parental leanness and overweight or obesity. The girls were grouped according to whether they had 2 lean parents (n = 30), 2 obese parents (n = 27), or 1 lean and 1 obese parent (n = 44). Basal metabolic rate (BMR), sleeping metabolic rate (SMR), 24-h EE, respiratory quotient, heart rate, and activity were measured by 24-h room calorimetry; free-living total EE (TEE), activity-related EE (AEE), and physical activity level were measured by doubly labeled water. EE was standardized by fat-free mass (FFM). RESULTS: There were no significant differences among familial groups in weight, height, fat mass, FFM, or percentage body fat. African American girls had a higher FFM than did white or Hispanic girls (P < 0.05). BMR, SMR, 24-h EE, respiratory quotient, heart rate, and activity levels were not significantly different among familial groups. Additionally, there were no significant familial group differences in TEE, AEE, or physical activity level. However, BMR, SMR, and TEE were lower in African American girls than in white girls (P < 0.05). CONCLUSION: There was no significant difference in EE between normal-weight, multiethnic prepubertal girls predisposed to obesity and those not predisposed to obesity.     

Energy expenditure under free-living conditions in normal-weight and overweight women.

Total energy expenditure under free-living conditions of 12 normal-weight and 26 overweight women was determined with the 2H2(18)O method. Overweight women tended to expend more energy (mean +/- SD, 11.20 +/- 1.79 MJ/d) than normal-weight women (9.46 +/- 0.87 MJ/d, P less than 0.005). Approximately half of this effect was explained by an increase in basal metabolic rate (BMR) in the overweight group compared with the normal-weight group (6.47 +/- 0.74 vs 5.68 +/- 0.39 MJ/d, respectively, P less than 0.005) and the other half by an increase in above-basal energy expenditure (4.73 +/- 1.49 vs 3.78 +/- 0.94 MJ/d, P less than 0.05). Total energy expenditure was approximately 1.7 times the BMR in both groups. After adjusting energy expenditure for weight or lean body mass by analysis of covariance, there was no significant difference between normal-weight and overweight groups. We conclude that most overweight subjects must consume more energy than lean subjects to maintain their excess weight, although some could maintain their obesity without eating more than lean subjects.     

Comparison of measured sleeping metabolic rate and predicted basal metabolic rate during the first year of life: evidence of a bias changing with increasing metabolic rate

OBJECTIVE: To compare measurements of sleeping metabolic rate (SMR) in infancy with predicted basal metabolic rate (BMR) estimated by the equations of Schofield. METHODS: Some 104 serial measurements of SMR by indirect calorimetry were performed in 43 healthy infants at 1.5, 3, 6, 9 and 12 months of age. Predicted BMR was calculated using the weight only (BMR-wo) and weight and height (BMR-wh) equations of Schofield for 0-3-y-olds. Measured SMR values were compared with both predictive values by means of the Bland-Altman statistical test. RESULTS: The mean measured SMR was 1.48 MJ/day. The mean predicted BMR values were 1.66 and 1.47 MJ/day for the weight only and weight and height equations, respectively. The Bland-Altman analysis showed that BMR-wo equation on average overestimated SMR by 0.18 MJ/day (11%) and the BMR-wh equation underestimated SMR by 0.01 MJ/day (1%). However the 95% limits of agreement were wide: -0.64 to +0.28 MJ/day (28%) for the former equation and -0.39 to +0.41 MJ/day (27%) for the latter equation. Moreover there was a significant correlation between the mean of the measured and predicted metabolic rate and the difference between them. CONCLUSIONS: The wide variation seen in the difference between measured and predicted metabolic rate and the bias probably with age indicates there is a need to measure actual metabolic rate for individual clinical care in this age group.     

Comprehensive assessment of the components of energy expenditure in infants using a new infant respiratory chamber.

BACKGROUND: Current methods for energy expenditure (EE) measurements in term infants do not include simultaneous measurements of basal and sleeping metabolic rates (BMR and SMR) or a measure of physical activity (PA). Furthermore, prediction equations for calculating EE are not appropriate for use in infants with metabolic disorders. OBJECTIVE: To develop and utilize a new infant respiratory chamber for simultaneous measurements of EE (kJ/d), preprandial BMR (kJ/d), SMR (kJ/d) and an index of PA (oscillations/min/kg body weight) in infants with a variety of metabolic disorders, for up to four hours in a hospital setting, while allowing parental interaction in a comfortable environment. METHODS: We obtained simultaneous measurements of EE, BMR, SMR and PA in 21 infants (66+/-73 days of age, 4.5+/-1.7 kg body weight, 55+/-8 cm in length and 16+/-7% body fat) using our new infant respiratory chamber. Six of these infants were healthy, seven had thyroid dysfunction, five were HIV-exposed, one had AIDS, one had intrauterine and postnatal growth retardation and one was a hypothermic preterm infant. Energy expenditure, BMR and SMR were extrapolated for 24 hours. Body composition was estimated by skin-fold thickness, using age-appropriate formulae. Basal metabolic rate obtained with the infant respiratory chamber was compared to BMR that was calculated using the appropriate World Health Organization (WHO) equations. RESULTS: In all infants both extrapolated 24-hour EE and BMR correlated with fat-free mass (r = 0.89, p<0.01 and r = 0.88, p<0.01 respectively). Twenty-four hour EE also correlated with PA (r = 0.52, p<0.05). The HIV-exposed infants had higher BMR (p<0.05) than that calculated by the appropriate WHO equation. We found that the caloric requirements for the infant with growth retardation were underestimated based on the infant's weight and age. CONCLUSIONS: The infant respiratory chamber can measure all of the main components of EE. Some of the results obtained differed significantly from those obtained by the WHO equations; therefore, the new infant respiratory chamber is necessary for estimating EE in infants with metabolic and growth disorders.     

Does BMR represent BMR?: Overestimation in the BMR standards

An implicit assumption, that the post-absorptive resting metabolic rate (RMR) after light physical activity frequently permitted in the determination of basal metabolic rate (BMR) would not differ substantially from that measured upon awakening, was questioned as a possible factor of overestimation in the BMR standards. The supine RMRs measured with 15 overnight fasting subjects (males, aged 20–29) 10 and 20 min after awakening were 0.91 and 0.97 kcal/kg fat-free mass/h, indicating the rise of metabolic rate with time (a 7% increase in 10 minutes). After a 10-min walk, the RMRs increased by 20% as compared to the RMR taken 10-min after awakening and remained constant. The RMRs 1 to 3 h after breakfast were essentially the same as the Japanese BMR standards. All predicted basal energy expenditure from the Japanese BMR standards, Harris-Benedict equation, Robertson-Reid standards and Boothby-Sandiford standards overestimated the post-absorptive resting energy expenditure determined after a 10-min walk by 9 to 18%. Our findings suggest a possibility that the BMRs previously determined have not been rigorously standardized, and raise questions regarding the accuracy of widely used BMR standards in predicting basal energy requirements.     

Energy intake and expenditure of free-living, pregnant Colombian women in an urban setting.

BACKGROUND: This study examined the components of energy balance in poor, free-living pregnant women living in an urban setting of a developing country. OBJECTIVES: We tested the following hypotheses: 1) energy intake increases in pregnancy and is greater than when nonpregnant and nonlactating (NPNL), 2) basal metabolic rate (BMR) increases in pregnancy and the increase is positively correlated with prepregnancy fatness, and 3) energy expenditure in activity decreases in pregnancy and is lower than in NPNL women. DESIGN: Pregnant women were studied at 14.8 +/- 3.4 (n = 40), 25.0 +/- 3.2 (n = 54), and 34.9 +/- 2.4 (n = 43) wk gestation, and NPNL women at baseline (n = 114) and at 3 (n = 103) and 6 (n = 93) mo. Energy intake was measured by using estimated diet records and energy expenditure by using the flex heart rate method. Time allocation in physical activity was assessed by observation. RESULTS: In pregnant women, body weight, BMR, and energy intake increased but total daily energy expenditure (TDEE) did not change significantly. There were no significant changes in time allocation to selected activities except for lying down. In comparison with NPNL control subjects, women in late pregnancy had higher energy intakes and BMRs. Values for TDEE were not significantly different, but pregnant women expended less energy in activity and allocated more time to 2 energy-saving activities and less time to 2 energy-demanding activities. CONCLUSION: A decrease in energy expenditure in activity and changes in time allocation are important ways in which pregnant women meet the energy demands of pregnancy.     

Physical activities and energy expenditures of institutionalized Japanese elderly women

The daily energy expenditure and physical activity index of institutionalized Japanese elderly women were measured. One hundred and thirteen Japanese elderly women (aged 79.5 -/+ 7.0 y) who live in institutions for the elderly and receive meal services participated voluntarily. A dietary survey, energy metabolic study, and time study were carried out over three consecutive days, and the basal metabolic rate (BMR) and energy expenditure by physical activity were measured. The intensity of daily physical activity was based on the physical activity index (PAI: total/basal energy expenditure). The mean BMR was 881 +/- 145 kcal/d (20.9 +/- 3.8 kcal/kg BW). The PAI in individuals ranged from 1.01 to 1.57, the mean value was 1.26 +/- 0.14, and 64% of the subjects examined showed a lower value than 1.3 of PAI. From these values, the mean total energy expenditure was calculated as 1,112 +/- 231 kcal/d (26.2 +/- 5.2 kcal/kg BW).     

Prognostic value of energy metabolism in patients with viral liver cirrhosis

The effect of energy malnutrition on survival in patients with non-alcoholic viral liver cirrhosis has not been well defined. We characterized energy metabolism at study entrance and prospectively analyzed its effect on subsequent survival in cirrhotics. One hundred nine consecutive patients with viral liver cirrhosis and 22 healthy control subjects participated in the study. By indirect calorimetry after overnight bedrest and fasting, resting energy expenditure (REE) was measured and non-protein respiratory quotient (npRQ) was calculated. Survival of cirrhotics were followed for up to 8 y. Survival rate was estimated with the Kaplan-Meier method. REE at entrance was significantly higher than the predicted basal metabolic rate (BMR) in cirrhotics (P < 0.001). NpRQ was significantly lower in cirrhotics than in controls (P < 0.001). Survival rate was significantly lower in patients with low npRQ ( < 0.85) than in patients with scores above 0.85 (P < 0.01) and was significantly higher in normal metabolic patients (0.9 < REE/BMR < 1.1) than in hypometabolic (REE/BMR < 0.9) or hypermetabolic (1.1 < REE/BMR) patients (P < 0.05). The proportional hazards model showed that npRQ (relative risk = 0.0003, 95% confidence interval = 0.0000-0.0970), REE/BMR (0.0199, 0.0007-0.5652), prothrombin time, and ammonia were independent significant factors determining survival. Thus evaluation of energy metabolism can be used to predict survival in patients with viral liver cirrhosis.     

Basal metabolic rate of Colombian children 2-16 y of age: ethnicity and nutritional status.

Measurements of basal metabolic rate (BMR) were made in 528 children 2-16 y of age living in underprivileged areas of the city of Cali, Colombia (153 control and 186 undernourished boys, 93 control and 96 undernourished girls). The data are related to BMR calculated from the equations of Schofield and to estimates of the lean body mass (LBM). The ethnic composition of the subjects was 80% mestizo (mixed European and South Amerindian ancestry), 15% black, and 5% white. The data do not show any variations due to race in these subjects. The Schofield equations overestimate the BMR of boys by approximately 6% whereas the estimation of BMR in girls is not significantly different from measured values. More than 65% of the variation in BMR of both nutritionally normal and undernourished boys and girls is explained by variation in body size as estimated by the LBM.     

Aging and energy expenditure

Whether sedentary energy expenditure is normal or lower in elderly people has not yet been clearly established. Twenty-four-hour energy expenditure (24EE) and its different components were measured by use of a respiratory chamber in elderly (17 male, 21 female; 71 +/- 6 y, mean +/- SD; 71.2 +/- 13.5 kg; 32 +/- 8% fat) and young (33 male, 31 female; 24 +/- 4 y; 84.5 +/- 23.1 kg; 25 +/- 13% fat) subjects. The elderly subjects had lower mean height (P less than 0.001), weight (P less than 0.01), and fat-free mass (P less than 0.001) but higher percent body fat (P less than 0.01) than did the young adults. Absolute 24EE, basal metabolic rate (BMR), and sleeping metabolic rate were significantly lower (P less than 0.01) in the elderly subjects than in the young subjects. However, after differences in fat-free mass, fat mass, and sex were adjusted for, only BMR was found to be lower in the elderly subjects (P less than 0.01). Despite a reduced adjusted BMR in older subjects, sedentary 24EE was decreased only in proportion to their reduced body size, suggesting that the lower energy intake reported in elderly people might be mainly related to lower physical activity in free-living conditions.     

Energy expenditure over 24 hours, thermal comfort and fat-free mass in Asian men

Energy expenditure while sitting or sleeping was measured over 24 h in eight young Asian immigrants to France by a suit calorimeter and also by continuous measurement of respiratory gas exchange. Fat-free mass (FFM) was estimated from skinfold measurements. The energy intake per kilogram FFM of the Asians was similar to a group of well-off North Americans of larger body size but similar body composition who had been the subjects of an earlier study. In both groups thermoneutrality was controlled by adjusting the circulating water temperature of the suit calorimeter according to the subjects' preferences. The hourly energy expenditure/kg FFM was 1.2 kcal during sleep and 1.7 kcal while sitting. The mean energy expenditure/kg FFM during a quiet day was 37 kcal/d or 1.5 kcal/h. Using published equations, the estimated BMR was 1490 kcal (6.2 MJ). This estimated value agrees quite well with the BMRs of these subjects as previously determined. In the metabolic room the daily sedentary energy expenditure averaged 1.15 BMR and the energy intake averaged 1.26 BMR for the study subjects in free-living conditions in an urban environment. This is below the 1.4 X BMR currently recommended as a 'minimum' energy intake for subjects of low activity.