Fatness reduces physical activity
Thursday March 20th, 2014
Children who carry the most weight may be caught in a vicious circle of inactivity aggravated by their size, researchers reported yesterday.
And in
some children their genes may stimulate them to pile on fat, adding to
their poor health, researchers warn.
The question of whether a higher body mass index (BMI) causes, or is caused by, less exercise has been the focus of research by Dr Rebecca Richmond and colleagues at Bristol University, UK.
The team analysed several genes that have been strongly linked to fatness, to see whether children who are genetically predisposed to an increased BMI had lower rates of physical activity.
Participants were involved in the Avon Longitudinal Study of Parents and Children (also known as Children of the 90s, or ALSPAC). Their BMI and total body fat were measured. In total, 14,062 children took part. A sub-group of 5,595 children had their total daily activity recorded with a movement-counting device.
Analysis showed that a higher BMI is likely to be "causally associated with lower daily activity". For every 3.3 point increase in BMI, the children recorded about three fewer minutes per day of moderate-to-vigorous-intensity activity.
Full results appear in PLOS Medicine.
The authors say that obese children "have a propensity to reduced levels of physical activity, which may in turn lead to further weight gain, and support targeting weight reduction in efforts to increase childhood activity levels.”
They write: "The study illustrates how genetics can be used to help find causal relationships in complex networks of observational measurements."
When relationships between obesity and activity are found to be causal, it becomes clear that "it is worth allocating considerable resources to assessing the impact of potential interventions," they conclude.
Richmond, R. C. et al. Assessing Causality in the Association between Child Adiposity and Physical Activity Levels: A Mendelian Randomization Analysis. PLoS Medicine 19 March 2014 doi:10.1371/journal.pmed.1001618 [abstract]
Tags: Child Health | Fitness | UK News
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