Components of Total Energy Expenditure in Healthy Young Women Are Not Affected after 14 Days of Feeding with Medium-Versus Long-Chain Triglycerides

PAPAMANDJARIS, ANDREA A., MATTHEW D. WHITE, AND PETER J. H. JONES. Components of total energy expenditure in healthy young women are not affected after 14 days of feeding with medium-versus long-chain triglycerides. Obes Res. Objective: To examine the effect of consumption of medium-chain triglycerides (MCT) vs. long-chain triglycerides (LCT) on total energy expenditure (TEE) and its components in young women during the second week of a 2-week feeding period. Research Methods and Procedures: Twelve healthy lean women (age: 22. 7±0. 7 years, body mass index [BMI]: 21. 5±0. 8 kg/m²) were fed weight maintenance diets containing 15% of energy as protein, 45% as carbohydrate, and 40% as fat, 80% of which was treatment fat, for 2 weeks in a randomized cross-over design separated by a 2-week washout period. Dietary fat was composed of triglycerides containing either 26% medium-chain fatty acids (MCFA) and 74% long-chain fatty acids (LCFA), or 2% MCFA and 98% LCFA. Free-living TEE was measured from day 7 to 14 on each dietary treatment using doubly labeled water (DLW). Basal metabolic rate (BMR) and thermic effect of food (TEF) were measured on days 7 and 14 using respiratory gas exchange analysis (RGE) for 30 minutes and 330 minutes, respectively. Activity-induced energy expenditure (AIEE) was derived as the difference between TEE and the sum of BMR and TEF. Results: The average TEE while consuming the MCT diet (2246±98 kcal/day) did not differ from that of the LCT diet (2186±138 kcal/day. BMR was significantly higher on the MCT diet on day 7 (1219±38 kcal/day vs. 1179±42 kcall day), but not on day 14; there was no effect of diet on TEF. There were no differences in BMR, TEF, or AIEE between diets when expressed as percentages of TEE. On average, BMR, TEF, and AIEE represented 54. 6%, 8. 2%, and 37. 2%, respectively, of TEE. Discussion: Results suggest that between day 7 and day 14 feeding of MCT vs. LCT at these levels, TEE is not affected and that increases seen in energy expenditure following MCT feeding may be of short duration. Thus, compensatory mechanisms may exist which blunt the effect of MCT on energy components over the longer term.     

Differences in daily energy expenditure in lean and obese women: the role of posture allocation

Objective: A low resting metabolic rate (RMR) is considered a risk factor for weight gain and obesity; however, due to the greater fat‐free mass (FFM) found in obesity, detecting an impairment in RMR is difficult. The purposes of this study were to determine the RMR in lean and obese women controlling for FFM and investigate activity energy expenditure (AEE) and daily activity patterns in the two groups. Methods and Procedures: Twenty healthy, non‐smoking, pre‐menopausal women (10 lean and 10 obese) participated in this 14‐day observational study on free‐living energy balance. RMR was measured by indirect calorimetry; AEE and total energy expenditure (TEE) were calculated using doubly labeled water (DLW), and activity patterns were investigated using monitors. Body composition including FFM and fat mass (FM) was measured by dual energy X‐ray absorptiometry (DXA). Results: RMR was similar in the obese vs. lean women (1601 ± 109 vs. 1505 ± 109 kcal/day, respectively, P = 0.12, adjusting for FFM and FM). Obese women sat 2.5 h more each day (12.7 ± 3.2 h vs. 10.1 ± 2.0 h, P < 0.05), stood 2 h less (2.7 ± 1.0 h vs. 4.7 ± 2.2 h, P = 0.02) and spent half as much time in activity than lean women (2.6 ± 1.5 h vs. 5.4 ± 1.9 h, P = 0.002). Discussion: RMR was not lower in the obese women; however, they were more sedentary and expended less energy in activity than the lean women. If the obese women adopted the activity patterns of the lean women, including a modification of posture allocation, an additional 300 kcal could be expended every day.     

Arg64β3‐Adrenoceptor Variant and the Components of Energy Expenditure

Objective: To determine Trp64Arg β₃‐adrenoceptor genotype‐specific differences in the components of energy expenditure. Hypothesis: We hypothesized that resting metabolic rate (RMR) and physical activity levels would be lower and that thermic effect of feeding (TEF) would be higher in those with the Arg64 allele. Research Methods and Procedures: RMR and TEF were measured by indirect calorimetry, physical activity by questionnaire, and total energy expenditure by the doubly labeled water method. Genotype‐specific measures were compared using ANOVA and analysis of covariance (ANCOVA). Results: RMR in Arg64 homozygotes was significantly lower than in Trp64 homozygotes [Arg64, 1373 ± 259 kcal/d (n = 15) vs. Trp64Arg, 1538 ± 238 kcal/d (n = 25) vs. Trp64, 1607 ± 290 kcal/d (n = 22); p < 0.01]. TEF was significantly higher in Arg64 homozygotes compared with Trp64 homozygotes (Arg64, 359 ± 28 kcal/d; Trp64Arg, 322 ± 22 kcal/d; and Trp64, 279 ± 23 kcal/d; p < 0.05). No differences were identified between genotypes in physical activity or in total energy expenditure. Discussion: Our results suggest that the Arg64 β₃‐adrenoceptor allele contributes significantly to the genetic variability in both RMR and TEF.     

Effect of calorie restriction on the free-living physical activity levels of nonobese humans: results of three randomized trials

The objective of this study was to evaluate the influence of calorie restriction (CR) on free-living physical activity levels among humans. Data were from three CALERIE phase I site-specific protocols. Participants were nonobese (body mass index = 23.5-29.9 kg/m2 adults randomly assigned to 25% CR, low-calorie diet (LCD, 890 kcal/day supplement diet until 15% weight loss, then weight maintenance), or control at Pennington Biomedical Research Center (PBRC); 30% or 10% CR at Tufts University; and 20% CR or control at Washington University School of Medicine (WUSM). Activity was measured at months 0, 3, and 6 (PBRC) and at months 0, 3, 6, 9, and 12 (WUSM and Tufts). Total daily energy expenditure (TEE) by doubly labeled water and resting metabolic rate (RMR) were used to compute activity energy expenditure: AEE = TEE - RMR - 0.1 * TEE. Accelerometry and 7-day recall categorized activities by intensity. At Tufts, the 10% and 30% CR groups experienced significant decreases in AEE at months 6, 9, and 12. At month 6, a larger decrease in AEE was observed in the CR than the control group at WUSM. At months 3 and 6, larger decreases in AEE were observed in the CR and LCD groups than the control group at PBRC. Accelerometry and 7-day PAR did not consistently detect changes in activity categories. CR-associated changes in AEE were variable but, generally, reduced the energy deficit, which would reduce the expected rate of weight loss. Accelerometry and recall did not consistently explain reduced AEE, suggesting that increased muscle efficiency and/or decreased fidgeting accounted for decreased AEE. Inaccuracy of accelerometry and recall also likely negatively affected sensitivity.     

Energy requirements and physical activity in free-living older women and men: a doubly labeled water study

Determinants of daily energy needs and physicalactivity are unknown in free-living elderly. This study examineddeterminants of daily total energy expenditure (TEE) andfree-living physical activity in older women(n = 51; age = 67 ± 6 yr) and men(n = 48; age = 70 ± 7 yr) by usingdoubly labeled water and indirect calorimetry. Usingmultiple-regression analyses, we predicted TEE by using anthropometric,physiological, and physical activity indexes. Data were collected onresting metabolic rate (RMR), body composition, peak oxygen consumption(O_{2 peak}),leisure time activity, and plasma thyroid hormone. Data adjusted forbody composition were not different between older women and men,respectively (in kcal/day): TEE, 2,306 ± 647 vs. 2,456 ± 666;RMR, 1,463 ± 244 vs. 1,378 ± 249; and physical activity energyexpenditure, 612 ± 570 vs. 832 ± 581. In a subgroup of 70 womenand men, RMR andO_{2 peak}explained approximately two-thirds of the variance in TEE(R² = 0.62;standard error of the estimate = ±348 kcal/day). Crossvalidation ofthis equation in the remaining 29 women and men was successful, with nodifference between predicted and measured TEE (2,364 ± 398 and2,406 ± 571 kcal/day, respectively). The strongest predictors ofphysical activity energy expenditure(P < 0.05) for womenand men were O_{2 peak}(r = 0.43), fat-free mass(r = 0.39), and body mass(r = 0.34). In summary, RMR andO_{2 peak} are importantindependent predictors of energy requirements in the elderly.Furthermore, cardiovascular fitness and fat-free mass are moderatepredictors of physical activity in free-living elderly.

     

Comparison of Methods for Achieving 24‐Hour Energy Balance in a Whole‐Room Indirect Calorimeter

Objective: To evaluate and compare methods for achieving 24‐hour energy balance in a whole‐room indirect calorimeter. Research Methods and Procedures: Twenty‐four‐hour energy expenditure (EE) for 34 healthy adults (16 women, 18 men) was measured in a calorimeter during a prestudy day and on a subsequent nonconsecutive assessment day (AD). Several methods for estimating EE on the AD using activity factors or regression equations with data available before the AD [anthropometrics, body composition, resting metabolic rate (RMR), sleeping metabolic rate (SMR) on prestudy day, 24‐hour EE on prestudy day] were compared for predictive accuracy. Results: Use of a 24‐hour calorimeter stay gave the smallest mean absolute error (119 ± 16 kcal/d) and smallest single maximum error (361 kcal/d). However, several other methods were only slightly, and not significantly, less accurate (e.g., mean absolute error = 131 ± 17, 140 ± 20, and 141 ± 22 kcal/d and greatest error = 384, 370, and 593 kcal/d for anthropometric, RMR, and SMR regression equations, respectively). Fat‐free mass alone and SMR with a simple activity factor were seen to be less accurate. Discussion: Our results indicate that there may be some improvement in achieving 24‐hour energy balance in a metabolic chamber by using a preceding 24‐hour calorimeter stay; that only slightly less accurate predictions can be obtained using a combination of anthropometric, body composition, and/or RMR measurements; and that there is little or no advantage in using SMR from a previous overnight calorimeter stay.     

Effect of Diet Composition and Weight Loss on Resting Energy Expenditure in the POUNDS LOST Study

Weight loss reduces energy expenditure, but it is unclear whether dietary macronutrient composition affects this reduction. We hypothesized that energy expenditure might be modulated by macronutrient composition of the diet. The Prevention of Obesity Using Novel Dietary Strategies (POUNDS) LOST study, a prospective, randomized controlled trial in 811 overweight/obese people who were randomized in a 2 × 2 design to diets containing 20en% or 40en% fat and 15en% or 25en% protein (diets with 65%, 55%, 45%, and 35% carbohydrate) provided the data to test this hypothesis. Resting energy expenditure (REE) was measured at baseline, 6, and 24 months using a ventilated hood. REE declined at 6 months by 99.5 ± 8.0 kcal/day in men and 55.2 ± 10.6 kcal/day in women during the first 6 months. This decline was related to the weight loss, and there was no difference between the diets. REE had returned to baseline by 24 months, but body weight was still 60% below baseline. Measured REE at 6 months was significantly lower than the predicted (?18.2 ± 6.7 kcal/day) and was the result of significant reductions from baseline in the low‐fat diets (65% or 55% carbohydrate), but not in the high fat diet groups. By 24 months the difference had reversed with measured REE being slightly but significantly higher than predicted (21.8 ± 10.1 kcal/day). In conclusion, we found that REE fell significantly after weight loss but was not related to diet composition. Adaptive thermogenesis was evident at 6 months, but not at 24 months.     

Resting metabolic rate and lung function in fasted and fed rough-toothed dolphins,Steno bredanensis

We measured resting metabolic rate (RMR), tidal volume (V_T), breathing frequency (f_R), respiratory flow, and end-expired gases in rough-toothed dolphins (Steno bredanensis) housed in managed care after an overnight fast and 1–2 hr following a meal. The measured average (± standard deviation) V_T (4.0 ± 1.3 L) and f_R (1.9 ± 1.0 breaths/min) were higher and lower, respectively, as compared with estimated values from both terrestrial and aquatic mammals, and the average V_T was 43% of the estimated total lung capacity. The end-expired gas levels suggested that this species keep alveolar O₂ (10.6% or 80 mmHg) and CO₂ (7.6% or 57 mmHg), and likely arterial gas tensions, low and high, respectively, to maximize efficiency of gas exchange. We show that following an overnight fast, the RMR (566 ± 158 ml O₂/min) was 1.8 times the estimated value predicted by Kleiber for terrestrial mammals of the same size. We also show that between 1 and 2 hr after ingestion of a meal, the metabolic rate increases an average of 29% (709 ± 126 ml O₂/min). Both body mass (M_b) and f_R significantly altered the measured RMR and we propose that both these variables should be measured when estimating energy use in cetaceans.     

Effect of calorie restriction on resting metabolic rate and spontaneous physical activity

Objective: It is unclear if resting metabolic rate (RMR) and spontaneous physical activity (SPA) decrease in weight‐reduced non‐obese participants. Additionally, it is unknown if changes in SPA, measured in a respiratory chamber, reflect changes in free‐living physical activity level (PAL). Research Methods and Procedures: Participants (N = 48) were randomized into 4 groups for 6 months: calorie restriction (CR, 25% restriction), CR plus structured exercise (CR+EX, 12.5% restriction plus 12.5% increased energy expenditure via exercise), low‐calorie diet (LCD, 890 kcal/d supplement diet until 15% weight loss, then weight maintenance), and control (weight maintenance). Measurements were collected at baseline, Month 3, and Month 6. Body composition and RMR were measured by DXA and indirect calorimetry, respectively. Two measures of SPA were collected in a respiratory chamber (percent of time active and kcal/d). Free‐living PAL (PAL = total daily energy expenditure by doubly labeled water/RMR) was also measured. Regression equations at baseline were used to adjust RMR for fat‐free mass and SPA (kcal/d) for body weight. Results: Adjusted RMR decreased at Month 3 in the CR group and at Month 6 in the CR+EX and LCD groups. Neither measure of SPA decreased significantly in any group. PAL decreased at Month 3 in the CR and LCD groups, but not in the CR+EX group, who engaged in structured exercise. Changes in SPA in the chamber and free‐living PAL were not related. Discussion: Body weight is defended in non‐obese participants during modest caloric restriction, evidenced by metabolic adaptation of RMR and reduced energy expenditure through physical activity.     

Seasonal Variation in Total Energy Expenditure and Physical Activity in Dutch Young Adults

Objective: The impact of season on energy expenditure and physical activity is not well quantified. This study focused on summer‐winter differences in total energy expenditure (TEE) and physical activity. Research Methods and Procedures: Twenty‐five healthy Dutch young adults, living in an urban environment, were measured in the summer season and the winter season. TEE was measured using doubly labeled water, and sleeping metabolic rate (SMR) was measured during an overnight stay in a respiration chamber. Subsequently, the physical activity level (PAL = TEE/SMR) and activity‐related energy expenditure [(0.9 × TEE) ? SMR] were calculated. Maximal mechanical power (W_max) was determined with an incremental test on a cycle ergometer. Body composition was measured with hydrostatic weighing and deuterium dilution using Siri's three‐compartment model. Results: There was no difference in TEE between seasons. PAL was higher in summer than in winter (1.87 ± 0.22 vs. 1.76 ± 0.18; p < 0.001), and the difference was higher for men than for women (0.20 ± 0.14 vs. 0.05 ± 0.16; p = 0.04). The difference in PAL between seasons was dependent on the initial activity level. There was a strong linear relation (R² = 0.48) between PAL and physical fitness (W_max/fat‐free mass), but W_max/fat‐free mass did not change between seasons in response to the lower PAL in winter. Discussion: The extent of the changes in PAL is of physiological significance, and seasonality in physical activity should be taken into account when studying physical activity patterns or relationships between physical activity and health.     

Differential Metabolic Effects of Energy Restriction in Dogs Using Diets Varying in Fat and Fiber Content

The role of dietary fat and fiber in energy restriction for the management of obesity was examined. Twelve male castrated dogs were energy restricted for 7 weeks by feeding 60% of their calculated maintenance energy requirements (MER = 1500 kcal/m²/d) for ideal body weight. Six dogs were restricted on a high-fat (35.4 kcal% from fat), low-fiber (2.9% dry matter basis [DMB]) diet while the other six dogs were restricted on a low-fat (24.5 kcal% from fat), high-fiber (27% DMB) diet. Compared with the high-fat, low-fiber diet, energy restriction on the low-fat, high-fiber diet resulted in significantly greater decreases in body fat (1472 ± 166 vs. 853 ± 176 g; p < 0.05) and total serum cholesterol concentrations (108.7 ± 11.3 vs. 51.5 ± 13.9 mg/dL; p< 0.005). Reductions in body weight (2.86 ± 0.3 vs. 2.14 ± 0.3 kg; p< 0.09), and mean arterial blood pressure (17.4 ± 6.1 vs. 6.7 ± 2.9 mmHg; p < 0.12) were also greater on the low-fat diet; however, these diet effects did not reach statistical significance. These data suggest that the fat and fiber content of the diet during energy restriction are important factors in the management of obesity.     

Changes in Sleeping and Basal Energy Expenditure and Substrate Oxidation Induced by Short Term Thyroxin Administration in Man

The present study was designed to explore the thermogenic effect of thyroid hormone administration and the resulting changes in nitrogen homeostasis. Normal male volunteers (n=7) received thyroxin during 6 weeks. The first 3-week period served to suppress endogenous thyroid secretion (180μg T₄/day). This dose was doubled for the next 3 weeks. Sleeping energy expenditure (respiratory chamber) and BMR (hood) were measured by indirect calorimetry, under standardized conditions. Sleeping heart rate was continuously recorded and urine was collected during this 12-hour period to assess nitrogen excretion. The changes in energy expenditure, heart rate and nitrogen balance were then related to the excess thyroxin administered. After 3 weeks of treatment, serum TSH level fell to 0.15 mU/L, indicating an almost complete inhibition of the pituitary-thyroid axis. During this phase of treatment there was an increase in sleeping EE and sleeping heart rate, which increased further by doubling the T₄ dose (ΔEE: +8.5 ± 2.3%, Δ heart rate +16.1 ± 2.2%). The T₄ dose, which is currently used as a substitutive dose, lead to a borderline hyperthyroid state, with an increase in EE and heart rate. Exogenous T₄ administration provoked a significant increase in urinary nitrogen excretion averaging 40%. It is concluded that T₄ provokes an important stimulation of EE, which is mostly mediated by an excess protein oxidation.     

Male Weasels Decrease Activity and Energy Expenditure in Response to High Ambient Temperatures

The heat dissipation limit (HDL) hypothesis suggests that the capacity of endotherms to dissipate body heat may impose constraints on their energy expenditure. Specifically, this hypothesis predicts that endotherms should avoid the detrimental consequences of hyperthermia by lowering their energy expenditure and reducing their activity in response to high ambient temperatures (T_a). We used an extensive data set on the daily energy expenditure (DEE, n = 27) and the daily activity time (AT, n = 48) of male weasels (Mustela nivalis) during the spring and summer breeding season to test these predictions. We found that T_a was related in a “hump-shaped” (i.e. convex) manner to AT, DEE, resting metabolic rate (RMR) and metabolic scope (the ratio of DEE to RMR). These results support the HDL hypothesis because in response to warm T_as male weasels reduced their AT, DEE, and RMR. Although the activity and energy expenditure of large endotherms are most likely to be constrained in response to warm T_as because they are less able to dissipate heat, our results suggest that small endotherms may also experience constraints consistent with the HDL hypothesis.     

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 ques tionnaire (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.     

HUM5007, a novel combination of thermogenic compounds, and 3-acetyl-7-oxo-dehydroepiandrosterone: each increases the resting metabolic rate of overweight adults

This study tested the hypothesis that 3-acetyl-7-oxo-dehydroepiandrosterone alone (7-Keto) and in combination with calcium citrate, green tea extract, ascorbic acid, chromium nicotinate and cholecalciferol (HUM5007) will increase the resting metabolic rate (RMR) of overweight subjects maintained on a calorie-restricted diet. In this randomized, double-blind, placebo-controlled, crossover trial, overweight adults on a calorie-restricted diet were randomized to three 7-day treatment periods with 7-Keto, HUM5007 or placebo. Resting metabolic rate was measured by indirect calorimetry at the beginning and end of each treatment period with a 7-day washout between testing periods. Of 45 subjects enrolled, 40 completed the study (30 women, 10 men; mean age, 38.5 years; mean mass index, 32.0 kg/m(2)). During the placebo treatment, RMR decreased by 3.9% (75+/-111 kcal/day; mean+/-S.D.); however, RMR increased significantly by 1.4% (21+/-115 kcal/day) and 3.4% (59+/-118 kcal/day) during the 7-Keto and HUM5007 treatment periods, respectively (each compared to placebo, P=.001). No significant differences were found between the treatment periods with respect to compliance or adverse events. In this study, the administration of HUM5007 or 7-Keto reversed the decrease in RMR normally associated with dieting. HUM5007 and 7-Keto increased RMR above basal levels and may benefit obese individuals with impaired energy expenditure. HUM5007 and 7-Keto were generally well tolerated and no serious adverse events were reported.     

Resistance training increases total daily energy expenditure in disabled older women with coronary heart disease.

Physical activity energy expenditure (PAEE) is a determinant of prognosis and fitness in older patients with coronary heart disease (CHD). PAEE and total energy expenditure (TEE) are closely related to fatness, physical function, and metabolic risk in older individuals. The goal of this study was to assess effects of resistance training on PAEE, TEE, and fitness in older women with chronic CHD and physical activity limitations (N = 51, mean age: 72 + 5 yr). The study intervention consisted of a progressive, 6-mo program of resistance training vs. a control group condition of low-intensity yoga and deep breathing. The study interventions were completed by 42 of the 51 participants. The intervention group manifested a 177 +/- 213 kcal/day (+9%) increase in TEE, pre- to posttraining, measured by the doubly labeled water technique during a nonexercise 10-day period (P < 0.03 vs. controls). This was due to a 50 +/- 74 kcal/day (4%) increase in resting metabolic rate measured by indirect calorimetry (P < 0.01, P < 0.05 vs. controls) and a 123 +/- 214 kcal/day (9%) increase in PAEE (P < 0.03, P = 0.12 vs. controls). Resistance training was associated with significant increases in upper and lower body strength, but no change in fat-free mass, measured by dual X-ray absorptiometry, or left ventricular function, measured by echocardiography and Doppler. Women in the control group showed no alterations in TEE or its determinants. There were no changes between groups in body composition, aerobic capacity, or measures of mental depression. These results demonstrate that resistance training of 6-mo duration leads to an increase in TEE and PAEE in older women with chronic CHD.     

Physical activity in aging: comparison among young, aged, and nonagenarian individuals.

Physical activity (PA) is known to decline with age; however, there is a paucity of data on activity in persons who are in their nineties and beyond. We used objective and reliable methods to measure PA in nonagenarians (>or=90 yr; n=98) and hypothesized that activity would be similar to that of aged (60-74 yr; n=58) subjects but less than in young (20-34 yr; n=53) volunteers. Total energy expenditure (TEE) was measured by doubly labeled water over 14 days and resting metabolic rate (RMR) by indirect calorimetry. Measures of PA included activity energy expenditure adjusted for body composition, TEE adjusted for RMR, physical activity level (PAL), and activity over 14 days by accelerometry expressed as average daily durations of light and moderate activity. RMR and TEE were lower with increasing age group (P<0.01); however, RMR was not different between aged and nonagenarian subjects after adjusting for fat-free mass, fat mass, and sex. Nonagenarians had a lower PAL and were more sedentary than the aged and young groups (P<0.01); however, the nonagenarians who were more active on a daily basis walked further during a timed test, indicating higher physical functionality. For all measures of activity, no differences were found between young and aged volunteers. PA was markedly lower in nonagenarians compared with young and aged adults. Interestingly, PA was similar between young volunteers and those who were in their 60s and 70s, likely due to the sedentary nature of our society, particularly in young adults.     

Energy Expenditure in Lean and Obese Prepubertal Children

The relationship between energy expenditure and obesity was examined in prepubertal children. Consenting fifth graders underwent Tanner Staging, weight, height and skinfold measurements. Subjects were selected for further study to obtain equal numbers of girls and boys with a wide range of body composition. Weight, total daily energy expenditure (TDEE) by doubly labeled water (DLW), resting metabolic rate (RMR), and body composition were measured. Children were grouped into level of obesity based on tertiles of subscapular plus triceps skinfolds. The skinfold tertiles did quite well in grouping subjects by degree of obesity, as differences in percent fat in each tertile were significantly different. There were no differences in fat-free mass between the groups, while the highest tertile group weighed 14 kg more than the lowest. For DLW, energy expenditure was calculated using day 8 and day 9 urine samples as the final time point to examine precision. Mean energy expenditure using either day was nearly identical (2220 ± 400 vs. 2300 ± 370 kcal/d), with a CV of the difference of 5.5%. No differences in RMR, energy expended in activity, or TDEE between the three groups were observed. A reduction in RMR or TDEE could not explain differences in obesity in these prepubertal children. However, the fact that the heaviest children expended the same amount of energy in activity and had the same TDEE as the leanest, while weighing 14 kg more, indicates that the obese children had a reduced activity level.     

Energy Expenditure Compared to Physical Activity Measured by Accelerometry and Self-Report in Adolescents: A Validation Study

Background

Physical inactivity is responsible for 5.3 million deaths annually worldwide. To measure physical activity energy expenditure, the doubly labeled water (DLW) method is the gold standard. However, questionnaires and accelerometry are more widely used. We compared physical activity measured by accelerometer and questionnaire against total (TEE) and physical activity energy expenditure (PAEE) estimated by DLW.

Methods

TEE, PAEE (TEE minus resting energy expenditure) and body composition were measured using the DLW technique in 25 adolescents (16 girls) aged 13 years living in Pelotas, Brazil. Physical activity was assessed using the Actigraph accelerometer and by self-report. Physical activity data from accelerometry and self-report were tested against energy expenditure data derived from the DLW method. Further, tests were done to assess the ability of moderate-to-vigorous intensity physical activity (MVPA) to predict variability in TEE and to what extent adjustment for fat and fat-free mass predicted the variability in TEE.

Results

TEE varied from 1,265 to 4,143 kcal/day. It was positively correlated with physical activity (counts) estimated by accelerometry (rho  = 0.57; p = 0.003) and with minutes per week of physical activity by questionnaire (rho  = 0.41; p = 0.04). An increase of 10 minutes per day in moderate-to-vigorous intensity physical activity (MVPA) relates to an increase in TEE of 141 kcal/day. PAEE was positively correlated with accelerometry (rho  = 0.64; p = 0.007), but not with minutes per week of physical activity estimated by questionnaire (rho  = 0.30; p = 0.15). Physical activity by accelerometry explained 31% of the vssariability in TEE. By incorporating fat and fat-free mass in the model, we were able to explain 58% of the variability in TEE.

Conclusion

Objectively measured physical activity significantly contributes to the explained variance in both TEE and PAEE in Brazilian youth. Independently, body composition also explains variance in TEE, and should ideally be taken into account when using accelerometry to predict energy expenditure values.