Body movement and physical activity energy expenditure in children and adolescents: how to adjust for differences in body size and age

BACKGROUND: Physical activity data in children and adolescents who differ in body size and age are influenced by whether physical activity is expressed in terms of body movement or energy expenditure. OBJECTIVE: We examined whether physical activity expressed as body movement (ie, accelerometer counts) differs from physical activity energy expenditure (PAEE) as a function of body size and age. DESIGN: This was a cross-sectional study in children [n = 26; (+/-SD) age: 9.6 +/- 0.3 y] and adolescents (n = 25; age: 17.6 +/- 1.5 y) in which body movement and total energy expenditure (TEE) were simultaneously measured with the use of accelerometry and the doubly labeled water method, respectively. PAEE was expressed as 1) unadjusted PAEE [TEE minus resting energy expenditure (REE); in MJ/d], 2) PAEE adjusted for body weight (BW) (PAEE. kg(-1). d(-1)), 3) PAEE adjusted for fat-free mass (FFM) (PAEE. kg FFM(-1). d(-1)), and 4) the physical activity level (PAL = TEE/REE). RESULTS: Body movement was significantly higher (P = 0.03) in children than in adolescents. Similarly, when PAEE was normalized for differences in BW or FFM, it was significantly higher in children than in adolescents (P = 0.03). In contrast, unadjusted PAEE and PAL were significantly higher in adolescents (P < 0.01). CONCLUSIONS: PAEE should be normalized for BW or FFM for comparison of physical activity between children and adolescents who differ in body size and age. Adjusting PAEE for FFM removes the confounding effect of sex, and therefore FFM may be the most appropriate body-composition variable for normalization of PAEE. Unadjusted PAEE and PAL depend on body size.     

Dietary energy requirements of young adult men, determined by using the doubly labeled water method

We examined the hypothesis that current recommendations on dietary energy requirements may underestimate the total energy needs of young adult men, by measuring total energy expenditure (TEE) and resting energy expenditure (REE) in 14 weight-maintaining healthy subjects leading unrestricted lives. TEE and body composition were measured by using 2H(2)18O, and REE was measured by using indirect calorimetry. All subjects had sedentary full-time occupations and participated in strenuous leisure activities for 34 +/- 6 (SE) min/d. TEE and REE were 14.61 +/- 0.76 and 7.39 +/- 0.26 MJ/d, respectively, and 202 +/- 2 and 122 +/- 2 kJ.kg-1.d-1. There were significant relationships between TEE and both body fat-free mass (r = 0.732, P less than 0.005) and measured REE (r = 0.568, P less than 0.05). Measured TEE:REE values were significantly higher than the recommended energy requirement (1.98 +/- 0.09, compared with 1.55 or 1.67, P less than 0.005). These results are consistent with the suggestion that the current recommended energy intake for young adult men may underestimate total energy needs.     

Energy expenditure measured by doubly labeled water,activity recall,and diet records in the rural elderly

OBJECTIVE: The purpose of this study was to determine whether energy expenditure estimated from physical activity and energy intake were equivalent to total daily energy expenditure in an elderly rural population. METHODS: Twenty-seven elderly male (n = 14) and female (n = 13) subjects (mean age, 74 y) were recruited from a rural Pennsylvania population. Over a 2-wk period, total daily energy expenditure was measured by doubly labeled water (TEE) and estimated from 7-d physical activity recall factors multiplied by weight (PA(WT)), estimated basal metabolic rate (PA(BMR)) and resting energy expenditure from indirect calorimetry (PA(REE)), and energy intake from 3-d self-reported diet records (EI). Analysis of variance was used to determine significant within-subject differences in physical activity, energy intake, and energy expenditure. RESULTS: PA(REE) (men: 13.69 +/- 3.23 MJ, women: 9.51 +/- 2.40 MJ) and PA(BMR) (men: 13.69 +/- 2.99 MJ, women: 10.15 +/- 2.21 MJ) were not significantly different from TEE (men: 12.43 +/- 1.63 MJ, women: 9.44 +/- 0.90 MJ). EI (men: 8.66 +/- 2.34 MJ, women: 7.12 +/- 0.93 MJ) was significantly less than TEE, and PA(WT) (men: 17.03 +/- 4.07 MJ, women: 12.86 +/- 3.41 MJ) was significantly greater than TEE. CONCLUSIONS: Whereas 7-d physical activity recall determined with an age- and gender-specific estimate of resting metabolic rate or measured using indirect calorimetry accurately estimated TEE for this group of rural elderly, self-reported diet records consistently underestimated and physical activity recall determined with weight alone consistently overestimated energy expenditure measured by doubly labeled water.     

Relative influence of diet and physical activity on body composition in urban Chinese adults

BACKGROUND: The relative influence of diet and physical activity on body fatness remains uncertain. OBJECTIVE: The objective of the study was to investigate associations of dietary variables and physical activity with body fatness in urban Chinese adults. DESIGN: We conducted a cross-sectional study in 130 weight-stable men and women aged 35-49 y. Subjects were selected from upper and lower tertiles of dietary fat and physical activity on the basis of screening questionnaires. Dietary intake was assessed by weighed food intake, physical activity level (PAL) was calculated as the ratio of predicted total energy expenditure (TEE) to predicted resting energy expenditure, and body composition was measured with the use of (2)H(2)O. Reported energy intake and predicted TEE were validated against TEE determined with the use of (2)H(2)(18)O (n = 73). RESULTS: Body fatness was positively associated with dietary variety (ie, variety of ingredients) (partial r = 0.186, P = 0.039) and frequency of consuming restaurant foods (partial r = 0.237, P = 0.001) and negatively associated with PAL (partial r = -0.307, P = 0.001) in a multiple regression analysis that controlled for sex and confounders. The combined variance accounted for by dietary variety and restaurant food consumption (9.1%) was equivalent to that for PAL (9.4%). Neither dietary fat nor energy density predicted body fatness, but dietary energy density predicted within-subject day-to-day variation in reported energy intake (P < 0.001). CONCLUSIONS: Dietary variety, frequency of restaurant food consumption, and PAL significantly predicted body fatness in urban Chinese adults, but dietary fat did not. These findings support previous studies in US adults and suggest that dietary variables other than fat have an important influence on adult body composition.     

Relation of body mass index and body fatness to energy expenditure: longitudinal changes from preadolescence through adolescence

BACKGROUND: Although it is widely accepted that weight gain results when energy intake exceeds energy expenditure (EE), how reduced EE contributes to the development of obesity remains unclear. OBJECTIVE: We tested the hypothesis that reduced EE in the premenarcheal period in girls constitutes a risk factor for an increase in relative weight [body mass index (BMI) z score] and percentage of body fat (%BF) during adolescence. DESIGN: We measured EE at study entry in 196 premenarcheal nonobese girls. Resting metabolic rate (RMR) was measured by indirect calorimetry. Total energy expenditure (TEE) was measured by the doubly labeled water method. Activity energy expenditure (AEE) was calculated from RMR and TEE. After the baseline study, girls were followed annually until 4 y after menarche (x+/- SD: 7.1 +/- 2.6 y). At each visit, height, weight, and %BF by bioelectrical impedance were measured. Girls also completed annual food-frequency and activity questionnaires. Linear mixed effects modeling was used to evaluate the longitudinal relation between BMI z score and %BF and measures of baseline EE. RESULTS: We found no significant relation in change in %BF with RMR, AEE, or TEE. We observed a small positive relation between BMI z score and AEE and TEE (P < 0.05) but no significant relation with RMR. When we stratified by parental overweight, the findings were unchanged for RMR. TEE and AEE were positively related to BMI z score in girls of overweight parents. CONCLUSIONS: Our findings suggest that EE in the premenarcheal period is not a risk factor for increases in %BF or BMI z score in girls during adolescence.     

Seasonal fluctuation in energy balance among farmers in Northeast Thailand: the lack of response of energy intake to the change of energy expenditure

OBJECTIVE: The study aimed to clarify the seasonal fluctuations in energy balance and their factors among rice-growing farmers in Northeast Thailand whose rice production was enough to their food energy demand. DESIGN: Prospective and repeated measurements in the field. SETTING: A rain-fed rice-farming village. SUBJECTS: Eight pairs of husband and wife. INTERVENTIONS: In each of four periods in a year, anthropometry, energy expenditure survey with heart-rate monitoring and minute-by-minute activity recording, and food consumption survey were conducted for each subject for 4 days. RESULTS: The change of body weight was modest but differed significantly (P < 0.001) between pre-harvest and post-harvest seasons: 1.3 kg (2.3%) for males, 2.5 kg (4.3%) for females. Total energy expenditure (TEE) fluctuated markedly between the 4 seasons (P < 0.001 for males and females), but total energy intake (TEI) fluctuated to lesser extents (P < 0.05 for females only). In relation to energy expenditure, physiological indicators (except respiratory quotient) did not fluctuate throughout the year but behavioral indicators did. The changes in body weight were significantly correlated with the changes in TEE (r = 0.60, P < 0.05 for males; r = 0.83, P < 0.01 for females) but not with the changes in TEI; TEE and TEI were not correlated. CONCLUSIONS: The modest seasonal changes in body weight among rain-fed rice farmers in Northeast Thailand were caused by the lack of response of TEI to the change of TEE.     

Validity of the ActiReg system in assessing energy requirement in chronic obstructive pulmonary disease patients

BACKGROUND & AIMS: Malnutrition and weight loss are common in patients with chronic obstructive pulmonary disease (COPD) and effective nutritional support relies on accurate assessment of energy requirement. This could only be performed by measuring energy expenditure using objective methods. The aim of this study was to examine the validity of the ActiReg system in assessing energy requirement in non-hospitalized patients with severe COPD, using doubly labelled water (DLW) as criterion method. METHODS: Total energy expenditure (TEE) was assessed from 14 days DLW analysis in 13 patients. During the first 7 days TEE was simultaneously assessed using the ActiReg system, combining measured resting energy expenditure (REE) with physical activity monitoring. RESULTS: A difference of -88 (782) kJ d(-1) (P = 0.69) was observed between the ActiReg system and DLW. REE explained 52% of the variation in TEE from DLW. Adding physical activity energy expenditure from the ActiReg system (PAEE(AR) = TEE(AR)-REE) increased the explained variation in TEE from DLW with 16%. CONCLUSIONS: The ActiReg system is valid in assessing energy requirement in non-hospitalized patients with severe COPD. The unique feature of being able to discriminate within both the low intensity activity range and moderate-to-high intensity activity range makes the ActiReg system a valuable tool in clinical nutritional support.     

Energy intake and physical activity in Pima Indians: comparison with energy expenditure measured by doubly-labeled water

To test the validity of survey techniques for measuring diet and activity patterns of Pima Indians, sequential 24-hour recalls, a food frequency questionnaire (FFQ), and an activity questionnaire were compared to free-living energy expenditure. Total energy expenditure (TEE) measured by doubly labeled water was 13.27 +/- 2.95 MJ/d for the 12 males (mean +/- SD: 35 +/- 14 yr; 97 +/- 35 kg; 32 +/- 9% body fat) and 11.67 +/- 1.85 MJ/d for the 9 females (31 +/- 13 yr; 106 +/- 32 kg; 49 +/- 6% body fat). Energy intake assessed by 24-hour recall was 13.59 +/- 7.81 MJ/d for men and 9.29 +/- 2.77 MJ/d for women, compared to 12.84 + 2.85 and 9.40 + 2.61 MJ/d for men and women, respectively, by FFQ. Both dietary methods indicated significant underreporting by women when compared to TEE. Energy intake assessed by FFQ was significantly correlated with TEE (r=0.48, p=0.03). This was true with 24-hour recall energy intake only when data from two extremely large alcohol consumers were eliminated (r=0.64, p=0.03, N=19). Although a low level of activity was apparent, the activity questionnaire produced significant correlations with measurements of energy expenditure and therefore represents an important tool for examining the relationship between physical activity and diseases.     

Long-term changes in energy expenditure and body composition after massive weight loss induced by gastric bypass surgery

BACKGROUND: Little is known about the determinants of individual variability in body weight and fat loss after gastric bypass surgery or about the effects of massive weight loss induced by this surgery on energy requirements. OBJECTIVES: The objectives were to determine changes in energy expenditure and body composition with weight loss induced by gastric bypass surgery and to identify presurgery predictors of weight loss. DESIGN: Thirty extremely obese women and men with a mean (+/- SD) age of 39.0 +/- 9.6 y and a body mass index (BMI; in kg/m(2)) of 50.1 +/- 9.3 were tested longitudinally under weight-stable conditions before surgery and after weight loss and stabilization (14 +/- 2 mo). Total energy expenditure (TEE), resting energy expenditure (REE), body composition, and fasting leptin were measured. RESULTS: Subjects lost 53.2 +/- 22.2 kg body weight and had significant decreases in REE (-2.4 +/- 1.0 MJ/d; P < 0.001) and TEE (-3.6 +/- 2.5 MJ/d; P < 0.001). Changes in REE were predicted by changes in fat-free mass and fat mass. The average physical activity level (TEE/REE) was 1.61 at both baseline and follow-up (P = 0.98). Weight loss was predicted by baseline fat mass and BMI but not by any energy expenditure variable or leptin. Measured REE at follow-up was not significantly different from predicted REE. CONCLUSIONS: TEE and REE decreased by 25% on average after massive weight loss induced by gastric bypass surgery. REE changes were predicted by loss of body tissue; thus, there was no significant long-term change in energy efficiency that would independently promote weight regain.     

The USDA Automated Multiple-Pass Method accurately estimates group total energy and nutrient intake

The imperative to address the national obesity epidemic has stimulated efforts to develop accurate dietary assessment methods suitable for large-scale applications. This study evaluated the performance of the USDA Automated Multiple-Pass Method (AMPM), the computerized dietary recall designed for the National Health and Nutrition Examination Survey dietary survey, and 2 epidemiological methods [the Block food-frequency questionnaire (Block) and National Cancer Institute's Diet History Questionnaire (DHQ)] using doubly labeled water (DLW) total energy expenditure (TEE) and 14-d estimated food record (FR) absolute nutrient intake as criterion measures. Twenty highly motivated, normal-weight-stable, premenopausal women participated in a free-living study that included 2 unannounced AMPM recalls and completion of the Block and DHQ. AMPM and FR total energy intake (TEI) did not differ significantly from DLW TEE [AMPM: 8982 +/- 2625 kJ; FR: 8416 +/- 2217; DLW: 8905 +/- 1881 (mean +/- SD)]. Conversely, the questionnaires underestimated TEI by approximately 28% (Block: 6365 +/- 2193; DHQ: 6215 +/- 1976; P < 0.0001 vs. DLW). Pearson correlation coefficients for DLW TEE with each dietary method TEI showed a stronger linear relation for AMPM (r = 0.53; P = 0.02) and FR (r = 0.41; P = 0.07) than for the Block (r = 0.25; P = 0.29) and DHQ (r = 0.15; P = 0.53). Most mean absolute FR nutrient intakes were closely approximated by the AMPM but were significantly underestimated by the questionnaires. In highly motivated premenopausal women, the AMPM provides valid measures of group total energy and nutrient intake whereas the Block and DHQ yield underestimations.     

Energy balance in cystic fibrosis when stable and during a respiratory exacerbation

Background & aims: Undernutrition is common in young adult patients with cystic fibrosis (CF) and implies an imbalance between energy intake and total energy expenditure (TEE). The aim of this study was to measure energy intake and TEE expenditure in a group of patients when they were clinically stable at home and during an exacerbation of respiratory symptoms when they were in hospital receiving intravenous antibiotics.Methods: Eleven patients aged between 15 and 40 years with moderate respiratory disease, mean FEV₁ 51.4% predicted took part. An exacerbation was defined as>15% decrease in FEV₁, an increase in sputum production and a decision to treat in hospital with intravenous antibiotics. Resting energy expenditure (REE) was measured using indirect calorimetry and energy intake by 3 day food diaries. TEE expenditure was measured using 24 h heart rate and doubly isotopically labelled water.Results: REE was higher at the beginning of an exacerbation than the end, P<0.05. There was no significant difference in TEE during the stable period compared to the exacerbation 10.53(2.39) MJ/day compared to 8.77(1.59) MJ/day using doubly isotopically labelled water. There was no difference in energy intake during the exacerbation compared to the stable period, 11.19(2.31) MJ/day compared to11.77(2.30) MJ/day.Conclusions: There was no difference in TEE and energy intake when patients were unwell in hospital compared to when they were stable at home despite an increase in REE.     

Short-term effects of a progestational contraceptive drug on food intake, resting energy expenditure, and body weight in young women

BACKGROUND: Studies showed that hormonal fluctuations that occur over the human menstrual cycle affect energy intake and expenditure. However, little is known about the possible effects on body weight regulation that may arise when these cyclic changes are suppressed with hormonal contraceptives. OBJECTIVE: The aim of this study was to examine how a progestational contraceptive drug (depot medroxyprogesterone acetate) affects food intake, resting energy expenditure (REE), and body weight in young women. DESIGN: Twenty normal-weight women were tested in a single-blind, placebo-controlled experiment. Body weight, REE, and 3-d food intake (food provided) were measured in the follicular and luteal phases of 2 menstrual cycles before a single injection of depot medroxyprogesterone or saline solution was administered. Measurements were also taken 4 times after injection: in the luteal and follicular phases of 2 cycles in the placebo group and 2 wk apart (to mimic timing of the menstrual phases) in the drug group. RESULTS: Before injection, the phase of the menstrual cycle affected both energy intake and REE. The study participants consumed more energy (4.3%; P = 0.02) and expended more energy at rest (4.3%; P = 0.0002) in the luteal phase than in the follicular phase. Comparison of pre- and postinjection means showed that treatment with the contraceptive drug had no significant effects on energy intake, REE, or body weight. CONCLUSIONS: This study showed that, although phases of the menstrual cycle affected energy intake and REE, depot medroxyprogesterone acetate did not alter energy intake or expenditure or cause weight gain in young women.     

Energy expenditure is very high in extremely obese women

To test the hypothesis that total energy expenditure (TEE) and resting energy expenditure (REE) are low in extremely obese individuals, factors that could contribute to maintenance of excess weight, a cross-sectional study was conducted in 30 weight stable, extremely obese women [BMI (mean +/- SEM) 48.9 +/- 1.7 kg/m(2)]. TEE was measured over 14 d using the doubly labeled water method, REE and the thermic effect of feeding (TEF) were measured using indirect calorimetry, and activity energy expenditure (AEE) was calculated as TEE - (REE + TEF). Body composition was determined using a 3-compartment model. Subjects were divided into tertiles of BMI (37.5-45.0; 45.1-52.0; and 52.1-77.0 kg/m(2)) for data analysis. TEE and REE increased with increasing BMI tertile: TEE, 12.80 +/- 0.5, 14.67 +/- 0.5, and 16.10 +/- 0.9 MJ/d (P < 0.01); REE, 7.87 +/- 0.2, 8.78 +/- 0.3, and 9.94 +/- 0.6 MJ/d (P < 0.001), and these values were 29-38% higher than published means of measured TEE in nonobese individuals. No significant differences were observed among BMI tertiles for AEE, TEF, or physical activity level (PAL = TEE/REE, overall mean 1.64 +/- 0.16). The Harris-Benedict and WHO equations provided the closest estimates of REE (within 3%), whereas the obese-specific equations of Ireton-Jones overpredicted (40%) and Bernstein underpredicted (21%) REE. Extremely obese individuals have high absolute values for TEE and REE, indicating that excess energy intake contributes to the maintenance of excess weight. Standard equations developed for nonobese populations provided the most accurate estimates of REE for the obese individuals studied here. REE was not accurately predicted by equations developed in obese populations.     

Energetic cost of physical activity in cystic fibrosis children during Pseudomonas aeruginosa pulmonary exacerbation

Chronic pulmonary infection by Pseudomonas aeruginosa is observed in 50% of patients with cystic fibrosis and requires the use of recurrent intravenous therapy. A decrease of resting energy expenditure (REE) and an increase of physical activity (PA) after intravenous anti-P. aeruginosa therapy (IVAT) is observed while total energy expenditure (TEE) does not change. A decrease in the energetic cost of physical activity (ECPA) could be hypothesized but has never been studied. Our aim was to assess the evolution of ECPA after home IVAT in both standardized condition at hospital and in free-living condition twice before and after IVAT. Sixteen CF patients (nine boys, seven girls) chronically colonized by P. aeruginosa with a mean age of 12.1+/-2.3 years (range 7.1-14.6) were studied before and after IVAT. Each patient passed throughout a visit in hospital: weight, height and fat-free mass were measured. Then, energy expenditure (EE) measured by indirect calorimetry and heart rate (HR) were simultaneously recorded at different levels of PA: REE, and at different intensity of physical activities on a cycloergometer using an incremental increase of the power brake force. Physical activity energy expenditure (PAEE) was computed in laboratory condition using PAEE=EE-BEE (basal energy expenditure). Linear regression between PAEE and power brake force was fitted for each patient before and after IVAT. ECPA in standardized conditions was compared at different range of power brake force using area under the curve (AUC). After coming back at home, 24 h TEE using the heart rate monitoring technique and PA by triaxial accelerometry were simultaneously measured in free-living condition for 24 h during a school day. ECPA in free-living conditions was compared by the ratio PAEE:PA where PAEE=DEE-REE (DEE=daily energy expenditure). After IVAT, median AUC between 60 and 90 W in standardized condition decreased significantly by -15.4% (median 14.9, range 8.8-30.3 vs. median 12.6, range 8.5-17.6; P<0.05, Wilcoxon rank test) while the decrease for lower range of power work load did not reach significance. Spearman correlation was significant between variations of forced expiratory volume in 1 s and variation of AUC at 30-60 W before and after IVAT in standardized condition. In free-living conditions, ratio PAEE/PA did not vary significantly (median 3.4, range 1.6-6.4 vs. median 2.8, range 1.4-4.8; NS). Our data demonstrate a decrease of ECPA after IVAT in standardized conditions for moderate level of PA (60-90 W), but not in free-living conditions. The decrease of ECPA was probably due to a decrease in the energetic cost of breathing after IVAT, that is particularly relevant to promote PA in CF patients.     

Prediction of daily energy expenditure during a feeding trial using measurements of resting energy expenditure, fat-free mass, or Harris-Benedict equations

BACKGROUND: During feeding trials, it is useful to predict daily energy expenditure (DEE) to estimate energy requirements and to assess subject compliance. OBJECTIVE: We examined predictors of DEE during a feeding trial conducted in a clinical research center. DESIGN: During a 28-d period, all food consumed by 26 healthy, nonobese, young adults was provided by the investigators. Energy intake was adjusted to maintain constant body weight. Before and after this period, fat-free mass (FFM) and fat mass were assessed by using dual-energy X-ray absorptiometry, and DEE was estimated from the change (after - before) in body energy (DeltaBE) and in observed energy intake (EI): DEE = EI - DeltaBE. We examined the relation of DEE to pretrial resting energy expenditure (REE), FFM, REE derived from the average of REE and calculated from FFM [REE = (21.2 x FFM) + 415], and an estimate of DEE based on the Harris-Benedict equation (HB estimate) (DEE = 1.6 REE). RESULTS: DEE correlated (P < 0.001) with FFM (r = 0.78), REE (r = 0.73), average REE (r = 0.82), and the HB estimate (r = 0.81). In a multiple regression model containing all these variables, R(2) was 0.70. The mean (+/-SEM) ratios of DEE to REE, to average REE, and to the HB estimate were 1.86 +/- 0.06, 1.79 +/- 0.04, and 1.02 +/- 0.02, respectively. CONCLUSIONS: Although a slightly improved prediction of DEE is possible with multiple measurements, each of these measurements suggests that DEE equals 1.60-1.86 x REE. The findings are similar to those of previous studies that describe the relation of REE to DEE measured directly.     

Negative energy balance in male and female rangers: effects of 7 d of sustained exercise and food deprivation

BACKGROUND: A challenging 7-d ranger field exercise (FEX) by cadets in the Norwegian Military Academy provided a venue in which to study the effects of negative energy balance. OBJECTIVE: We quantified total energy expenditure (TEE), food intake, and changes in body composition in male and female cadets. DESIGN: TEE (measured by doubly labeled water), food intake, activity patterns (measured by accelerometry), and body composition (measured by dual-energy X-ray absorptiometry) were measured in 16 cadets (10 men and 6 women aged 21-27 y). RESULTS: The physically active (approximately 23 h/d) and semistarved (0.2-2.2 MJ/d) cadets lost weight (x +/- SD: men, -7.7 +/- 1.1 kg; women, -5.9 +/- 1.1 kg; P < 0.05). Absolute TEE differed by sex (men, 26.6 +/- 2.0 MJ/d; women, 21.9 +/- 2.0 MJ/d; P < 0.05) but body weight-specific TEE did not (men, 343 +/- 26 kJ . kg(-1) . d(-1); women, 354 +/- 18 kJ . kg(-1) . d(-1); NS). Fat-free mass (FFM) loss differed significantly by sex (men, -4.0 +/- 1.2 kg; women, -2.5 +/- 1.1 kg; P < 0.05), but percentage FFM loss did not (men, -6.3 +/- 1.9%; women, -5.6 +/- 2.4%). In contrast, absolute FM loss did not differ significantly by sex (men, -3.45 +/- 0.72 kg; women, -3.42 +/- 0.22 kg), but fat oxidation (men, 5.2 +/- 1.0 mg . min(-1) . kg FFM(-1); women, 7.3 +/- 0.5 mg . min(-1) . kg FFM(-1)) and the relative contribution of FM to TEE (men, 74 +/- 14%; women, 89 +/- 6%) were significantly greater in women than in men (P < 0.05). CONCLUSION: Female cadets maintained a significantly more fat-predominant fuel metabolism than did male cadets in response to sustained exercise and semistarvation.     

Determinants of free-living energy expenditure in normal weight and obese women measured by doubly labeled water

Total free-living energy expenditure (TEE) was measured in 9 normal weight controls and 5 obese women using the doubly labeled water (DLW) method. Resting energy expenditure (REE) and the thermic effect of food (TEF) were measured by indirect calorimetry and the energy cost of physical activity (PA) calculated by deduction, in order to quantify the components and identify determinants of free-living TEE. Although REE was quantitatively the major component of TEE in both groups, PA best explained the variability, contributing 76% to the variance in free-living TEE. The obese women had elevated values for TEE (12397 +/- 2565 vs. 8339 +/- 1787 kJ/d, mean +/- SD; p < 0.005), compared with the control women. PA (5071 +/- 2385 vs. 2552 +/- 1452; p < 0.05) and REE (6393 +/- 678 vs. 5084 +/- 259; p < 0.0005) were also raised in the obese, whereas TEF was not significantly different between the groups, accounting for 7.6% of energy expenditure for the obese and 8% for the control subjects. Body weight was the single best determinant of mean daily free-living TEE across both groups. We conclude that PA and body weight are the main determinants of free-living TEE.     

Low physical activity reduces total energy expenditure in women with rheumatoid arthritis: implications for dietary intake recommendations

BACKGROUND: Rheumatoid arthritis (RA) causes cachexia, a metabolic response characterized by loss of muscle mass and elevated resting energy expenditure (REE). However, energy expenditure in physical activity in subjects with RA is lower than that in healthy subjects. It is not known which effect predominates in regulating total energy expenditure (TEE), and thus whether the dietary energy requirements of subjects with RA are higher or lower than those of healthy subjects. OBJECTIVE: Our objective was to determine TEE in women with RA by using the reference method of doubly labeled water ((2)H(2)(18)O). DESIGN: In this case-control study, we examined 20 women with RA and 20 healthy women who were matched for age and body mass index. RESULTS: The patients with RA were cachectic (their body cell mass was 14% lower than that of the controls, P < 0.001), but REE was not elevated, reflecting good disease control. Mean (+/- SD) TEE was 1344 kJ/d lower in the patients than in the controls (9133 +/- 1335 compared with 10 477 +/- 1992 kJ/d; P < 0.02). The energy expenditure in physical activity of the patients was 1034 kJ/d lower than that of the controls (P < 0.04), which accounted for 77% of the difference in TEE between the 2 groups. The physical activity level (TEE/REE) of the patients also tended to be lower than that of the controls (1.70 +/- 0.24 compared with 1.89 +/- 0.36; P < 0.07). CONCLUSION: A low physical activity level is the main determinant of lower-than-normal TEE, and thus energy requirements, in women with RA.     

Hyperphagia contributes to the normal body composition and protein-energy balance in HIV-infected asymptomatic men

Wasting can occur at an early stage of HIV infection. Both reduced energy intake and increased resting energy expenditure (REE) have been considered as factors in wasting with predominant lean body mass loss, suggesting disturbances of protein metabolism. Our aim was to study protein-energy metabolism in relation to body composition and oral energy intake in asymptomatic patients with HIV infection but receiving no active antiretroviral therapy. Stable-weight asymptomatic male patients (n = 8) at stage A of HIV infection with a detectable viral load were compared with 9 healthy control men. Protein metabolism was studied in the postabsorptive state using a primed constant infusion of l-[1-(13)C]leucine and l-[2-(15)N]glutamine. REE was studied by indirect calorimetry, body composition by bioelectrical impedance, and energy intake by dietary records. BMI and lean body mass did not differ between patients and controls. In HIV-infected subjects, energy intake, protein breakdown, protein synthesis, and REE were 57% (P < 0.05), 18% (P < 0.05), 22% (P < 0.05) and 14% (P < 0.05) greater than in controls, respectively. REE and protein breakdown were correlated (r = 0.73, P < 0.05). The hormonal profile was normal in HIV-infected subjects with the exception of low urinary C-peptide and plasma reverse triiodothyronine. Plasma interleukin-6 and tumor necrosis factor-alpha were greater than in controls, but energy intake was 1.53 times the REE in the HIV-infected men. Thus, at the asymptomatic stage of HIV infection, increased protein turnover contributes to the increase in the REE. Moderate hyperphagia, which occurred despite increased levels of cytokines, in conjunction with increased protein synthesis maintains a normal body composition, without significant loss of lean body mass.     

Growth velocity, fat-free mass and energy intake are inversely related to viral load in HIV-infected children

The study objectives were to assess the relationships among human immunodeficiency virus (HIV) replication, energy balance, body composition and growth in children with HIV-associated growth failure (GF). Energy intake and expenditure, body composition and level of HIV RNA were measured in 16 HIV-infected children with growth failure (HIV+/GF+), defined as a 12-mo height velocity 相似文献