Longitudinal changes in fatness in white children: no effect of childhood energy expenditure

Abstract

Reduced energy expenditure may predispose children to the development of obesity, but there are limited longitudinal studies to support this theory. We studied 75 white, preadolescent children over 4 y by taking annual measures of body composition and resting energy expenditure (by indirect calorimetry) and two annual measures of total energy expenditure and physical-activity-related energy expenditure (by doubly labeled water). Body composition of parents was assessed at the onset of the study with use of underwater weighing. The major outcome variable was the individual rate of change in fat mass (FM) adjusted for fat-free mass (FFM). The influence of sex, energy expenditure components, initial FM, and parental FM on the rate of change in FM was analyzed by hierarchical linear modeling and analysis of variance. The rate of change in absolute FM was 0.89 +/- 1.08 kg/y (range: -0.44 to 5.6 kg/y). The rate of change in FM adjusted for FFM was 0.08 +/- 0.64 kg/y (range: -1.45 to 2.22 kg/y) and was similar among children of two nonobese parents and children with one nonobese or one obese parent, but was significantly higher in children with two obese parents (0.61 +/- 0.87 kg/y). The major determinants of change in FM adjusted for FFM were sex (greater fat gain in girls), initial fatness, and parental fatness. None of the components of energy expenditure were inversely related to change in FM. The main predictors of change in FM relative to FFM during preadolescent growth are sex, initial fatness, and parental fatness, but not reduced energy expenditure.

Role of physical activity in the prevention of obesity in children

“…Although there are good examples of an inverse relationship between obesity and physical activity in children, 81,82 and a positive relationship between obesity and physical inactivity, 83 some indices of physical activity (freeliving activity energy expenditure) are positively related to fatness and do not predict the development of body fat in children. 26 In addition, although it is generally agreed that television may be related to the onset of obesity and reduced physical activity in children, 45,59 with some prospective data suggesting that television viewing (as a marker for inactivity) in children predicts the development of obesity over time, 82 these relationships are not supported by all prior studies. 84 Laboratory studies show that ®tness and energy costs of speci®c activities are similar in lean and obese children after normalising for differences in body composition.…”

“…Although recent metabolic and genetic research has deepened our understanding of the physiological aspects of body weight regulation, there is very little evidence to support the concept that the development of obesity in children is determined by acute metabolic andaor genetic defects. 25,26 It is extremely unlikely that acute changes in the gene pool or alterations in metabolic rate have arisen and are responsible for the recent increase in obesity prevalence in the population. A more plausible explanation for the increasing prevalence of obesity relates to cultural changes accompanying societal development, such as a decreased requirement for physical activity and greater abundance and availability of food.…”

“…85,86 Similar to the results for physical activity, there are some studies suggesting that a low level of energy expenditure predicts obesity, 87 and others which do not support this hypothesis. 26 This section brie¯y reviews the relationship between physical activity and energy expenditure in the development of obesity.…”

Regular participation in sports is associated with enhanced physical fitness and lower fat mass in prepubertal boys

“…[15][16][17][18] However, reduced energy expenditure alone cannot explain the gain of fat mass during growth. 19,20 On the other hand, increased levels of physical activity are associated with a lower BMI in youths. [21][22][23] Exercise interventions in prepubertal obese children have already demonstrated that physical training during a short period of time (few months) has a favourable impact on body composition and some obesity-associated health factors.…”

Physical activity, television viewing and body mass index: a cross-sectional analysis from childhood to adulthood in the 1958 British cohort

“…Existing cross-sectional and longitudinal studies report inconsistent findings, both in children and adults; some report a protective effect of physical activity against obesity, others find no association and a few have suggested that higher activity is related to increased fatness. [1][2][3][4] This lack of consistency is likely to be partly due to the variety of methods used to measure body fat and energy expenditure or physical activity, but may also be due to gender, age and sociocultural differences in type or range of physical activity. In the UK, girls are only slightly less active than boys up to the age of about 7 y, but from then on through into adulthood, female subjects are noticeably less active than males, 5 a gender difference that is common across the Western world.…”