Nature versus nurture in childhood obesity: a familiar old conundrum

摘要

Childhood obesity is an emerging pandemic or the new millennium, and thus we urgently need to understand its causal web. During the past decade, the identification of an obesity gene and the development of new insights into the physiology of appetite regulation and energy metabolism led to great promise and excitement. Despite these advances, we have yet to uncover the complex dynamics of energy intake and energy expenditure (EE) in the context of a person's environment, behavior, and genes.One plausible pathway for nature to manifest itself is via modulation of thermogenesis, which in turn affects energy balance. A perennial question is whether obesity-prone persons have lower resting metabolic rates than do lean people, because this endogenous trait could be genetically modulated. Thus far, there is no consistent evidence directly linking lower metabolic rates to obesity, perhaps because the published information comes mostly from cross-sectional studies of obese subjects. The association between body mass index or fat mass and resting metabolic rate is paradoxical: heavy persons generally have high metabolic rates. This is counter to the expectation that excess energy storage in heavy persons is the result of parsimonious EE.