Contributing factors and variability of energy expenditure in non-obese, obese, and post-obese adolescents

Abstract

-Energy expenditure (EE) is a major determinant of energy balance and body composition. The objectives of this paper were to review the contributing factors of the main components of daily EE (DEE) and the inter-individual variability in these components in non-obese (NOb), obese (Ob), and post-obese (POb) adolescents. Body composition especially fat-free mass (FFM), is the major determinant of the basal metabolic rate which contributes 50-70% of DEE, whereas fat mass (FM) is a significant factor only in obese subjects. Physical activity is the second main variation factor of DEE, whereas growth, the thermic effect of food, and thermoregulation are generally of marginal importance. The energy costs and EE associated with various sedentary and physical activities were assessed in NOb, Ob and POb subjects both in standardised and in free-living conditions. The interindividual variability of DEE is high, even after adjustment for body composition, mainly because of great differences in time devoted to the various physical activities. DEE and EE associated with sleep and sedentary activities are significantly higher in Ob than in NOb, but not after adjustment for FFM. On the contrary, EE associated with physical activities is not significantly different between Ob and NOb adolescents, but 61% lower in Ob subjects after adjustment for body composition. Multidisciplinary weight-reduction programmes including moderate energy restriction and physical training result in great FM loss, maintenance of FFM, improvement of physical capacities, but reductions in organ and tissue metabolic rate and in EE associated with the various sedentary and physical activities, which may favour body weight regain in the less active POb subjects. body composition / basal metabolic rate / physical activity / thermoregulation

Temperature and photoperiod as environmental cues affect body mass and thermoregulation in Chinese bulbulsPycnonotus sinensis

“…Organs such as the liver, brain, heart and kidney collectively consume about 60% of an endotherm's total energy expenditure and consequently are major contributors to overall RMR (Daan et al, 1990;Vermorel et al, 2005). The elevation in RMR of the cold group was presumably related to metabolic and/or morphological adjustments, including changes in organ mass, required to meet the energy demands of acclimation to colder temperature conditions.…”

Validity of Physical Activity Indices for Adjusting Energy Expenditure for Body Size: Do the Indices Depend on Body Size?

“…We found that sizeindependent comparisons could be made using FFM. Moreover, previous studies succeeded in comparing physical activity using EE/FFM even between obese and nonobese adult subjects (Meijer et al, 1992) and between children and adolescents (Ekelund et al, 2004;Vermorel et al, 2005). On the basis of these results it appears that FFM has characteristics of both BW and RMRs.…”

“…However, differences in the relationships between body size and L-RMR and S-RMR were not clarified sufficiently. There is an alternative way to adjust EE for body size, namely, EE/FFM, with previous studies in children and adolescents suggesting that FFM may be the most appropriate variable for normalization of EE during physical activities (Ekelund et al, 2004;Vermorel et al, 2005). Intensity of daily total activity can be estimated by dividing total energy expenditure (TEE) by BW (TEE/BW) or by RMRs (TEE/L-RMR and TEE/S-RMR).…”

Adolescent obesity treatment in France

“…Pour qu'un adolescent dépasse au cours d'une activité le seuil de deux fois la dépense d'énergie au cours du sommeil, il est nécessaire que cette activité se déroule à l'extérieur. La simple marche en est la première occasion [5]. Toutefois, chez les adolescents, les activités spontanées mais suffisamment vigoureuses semblent conférer la meilleure protection contre l'obésité [6].…”