Tuesday, July 11, 2006

What we don't know about being fat?

A research agenda for obesity research:

We don't have a clear understanding of the connection between being somewhat overweight and being heathy. We are more certain that being obese (very overweight) results in poorer health. Long term, as our weight has increased, our longevity has improved. We have grown fatter but now live longer.

We are unsure that losing weight - perhaps even lots of weight - improves health for those who were originally very overweight. Losing lots of weight may worsen mortality. Most studies do not support the notion that weight loss among overweight people improves their mortality though it may reduce their mortality specifically due to weight-related disorders. If this is true then the modern passion for weight loss is sensibly motivated by aesthetics not health.

We are unsure that people can sustainably lose weight. Diets and exercise programs have short-run effects but invariably seem to fail longer-term. Is weight-gain a hard-wired trait?

As a particular case of this proposition: it is unclear that even 'well-designed' public health programs can lead to weight loss even if this is a good idea.

We don't know exactly why so many people are getting fat. Exercise or diet? Yes, certainly some mix of these two - by a 'law of nature' it must be so - but, exactly what, no-one knows. Or perhaps everyone knows and that's the problem. There are a myriad of theories explaining modern propensities to bulge but none works really well. We are not obviously getting lazier for example.

We don't know why poor people in developed countries are eating unhealthy foods when they are not time-poor and when healthy foods are cheaper alternatives?

This is an index of my modesty. On obesity we know little.


Tanya said...

Oh, please do forward this post to those commenters on Catallaxy's “Obesity as market failure?” thread. If ever there were commenters advancing policy ideas that they claimed are basee in good science (the good science of self control(!)) but who actually ignored evidence in order to push their ideological barrows, they can be found on that thread.

If you haven't already seen it, there was an interesting article in the New York Times magazine recently. The article looks at addiction (covering some of what you would know about drug addiction) but also referencing the role of dopamine in weight control. The research they highlight further contradicts the basis upon which some policy suggestions have been made.


patrick said...

Great post Harry, obesity certainly is very trendy to decry, but so much information surrounding it remains unknown - in addition to research methods being almost hilariously unreliable (self-reported BMIs, for example).

As you say, there is plenty of evidence that indicates you can be overweight (not obese), and plenty healthy. I suspect our current obsession with weight is at least as social as medical, and I find it particularly disturbing regarding children. I'm glad as a kid, I never thought once about my weight.

hc said...

tanya, I referred to that paper a week ago. To be fair I have also made strong sounding suggestions on obesity issues but I do think there is a lot we don't know.

FXH said...

I know this might be a tad simplistic but...

Most well nourished nations / people have continued to increase in height over the years, although I did see somewhere recently that the Dutch, I think it was, who were the tallest nation, had stopped increasing in height.

Surely if we increase in height with better nutrition we might also be expected to increase in width?

Maybe we should revise our "obesity" measurements and have a more sensible graduated nomenclature.

Say,10 categories:
1 - Too Skinny, 2 - Skinny 3 - a bit thin, 4 - about right, 5 - solid , 6 - a bit pudgy, 7 - getting fat, 8 - too fat, 9 - far too fat, 10 - obese.