Tuesday, February 15, 2011

Exercise won't prevent obesity in 8 year olds.

From the, “weight ain’t about exercise” file comes a small study that was reported on during the Obesity Society's 2010 Annual Scientific Assembly.

The presenters reported on the impacts of 6 years worth of energy expenditure data on children’s weights, BMIs, waist circumferences, fat percentiles and total fat masses at the age of 8. Forty-five children were investigated using doubly labeled water to determine total energy expenditures and both bio-impedance analysis and dual energy X-ray absorptiometry were used to explore fat free mass.

The working hypothesis of course was that kids with higher total energy expenditures (more active kids) should have lower BMIs and less fat mass than kids with the lowest energy expenditures.

There are two ways to look at the results. The more negative way to do so would be to harp on the fact that high levels of exercise didn’t associate with lower BMIs as gloomy, and in a move that may seem surprising to some of my readers, I'm not going to do that. Instead I find the results somewhat heartening in that at least as far as absolute weight goes, inactive kids are at no greater risk than active ones. For me that's somewhat heartening given how we can’t seem to figure out ways to make kids more active.

While far from a large study, the fact that there was no association found between energy expenditure and weight or body fat percentage is yet another redundant nail in the coffin of exercise being the answer to the prevention of childhood obesity.

That said, one thing the authors didn’t mention was whether or not there was any differences in the distribution of body fat among the more active kids in that there have been studies that demonstrate that while not having a marked impact on weight, exercise does seem to impact on how fat is distributed which in turn may well have an impact on health and weight related comorbidities.