Wednesday, 18 May 2016

The myth of the obesogenic environment


The full article is gated but the abstract is unequivocal about the findings:

The prevalence of obesity has doubled over the last 25 years. We estimate the effects of multiple socio-environmental factors (e.g., physical demands at work, restaurants, food prices, cigarette smoking, food stamps, and urban sprawl) on obesity using NLSY data. Then we use the Oaxaca–Blinder decomposition technique to approximate the contribution of each socio-environmental factor to the increase during this time. Many socio-environmental factors significantly affect weight, but none are able to explain a large portion of the obesity increase. Decreases in cigarette smoking consistently explains about 2–4 % of the increase in obesity and BMI. Food stamp receipt also consistently affects the measures of weight, but the small decrease in food stamp program participation during the period we examine actually dampened the increases in obesity and BMI. Collectively, the socio-environmental factors we examine never explain more than about 6.5 % of the weight increases.

So can we now shut up about banning advertising, refusing permission for fast-food shops near schools and a host of other irrelevances. The rise in obesity is down to a more sedantry lifestyle and that our energy intake hasn't declined as fast as our metabolic need for that energy.



Anonymous said...

Oh no Simon, if the population cannot be trusted to compensate for a sedentary lifestyle by increasing exercise and reducing calorie intake then we must help. We must ban advertising, we must ban fast food shops, we must mandate exercise, we must lobby for increased taxes, we must be given more money to do more studies, to lobby Government, to pay the media to run the press releases. After all our lively hoods depend on it.

Dan said...

One part of the increase in obesity may well be the prevalence of central heating. Whilst I was growing up, the only sources of heat in the house were two gas fires. We had a few electric heaters, which were never used because of cost, and that was it.

Feeling cold in winter? Put on more clothing. The bedrooms were not heated; more blankets was the answer to cold there. The house was single-glazed, and ice formation on the inside of the windows at night in winter was commonplace.

These days we have efficient central heating, which pushes the house temperature to twenty degrees Celsius whenever we are in the house.

This makes a big difference, since most of the energy demands of a warm-blooded animal like ourselves is not the energy needed to move about, but rather the energy to keep warm.