It’s worth noting that the correlation between income and body weight is very easy to destroy. In the U.S., if you collect a bunch of data on people’s weights and household incomes, you do find a negative raw correlation. But if you compare people of the same age and break the sample down seperately by sex, you find that the correlation between income and body weight is positive for men and negative for women. The claim that income is the most “reliable” predictor of body weight is difficult to assess because “reliable” is not a well-defined statistical term, but if he means “explains the most variation in,” then the claim is wrong, as education is more “reliable” in that sense, and higher education is correlated with lower body weight for both men and women.
More subtly, if folks like Drewnowksi were correct that it’s low income which causes obesity, we should observe that people get lighter if their income goes up for reasons beyond their control. A recent unpublished (but highly credible) study shows that higher EITC payments lead to higher, not lower, body weight. The causal effect of income on body weight appears to be positive.
In short, body weight and income are negatively correlated for women, but not for men. And that correlation does not appear to result from a causal effect of income on body weight, rather, it appears to be that some other factor causes both women’s body weights and incomes.
On the other hand, it is true that making crappy high energy density food relatively cheaper causes increases in obesity rates, particularly among adolescents. But it’s a pretty small effect.
Edit: and, yes, people do likes them some fat and sugar, go figure. See for example:
Yeomans MR, Gray RW. Opioid peptides and the control of human ingestive behaviour. Neuroscience and Biobehavioral Reviews 2002;26:713–28.
Levine AS, Kotz CM, Gosnell BA. Sugars and fats: the neurobiology of preference. Journal of Nutrition 2003;133:831S–4S.
Even at Chez Panisse, people likes them some tasty fat and sugar, e.g.:
Wednesday, April 25 $65
Fava bean and duck gizzard salad with pancetta
Steamed local halibut with leeks and Graves wine butter
Grilled Sonoma County Liberty duck breast with merlot, shallot, and black pepper sauce,
fried potatoes, and roasted turnips
Rhubarb tart with Sauternes ice cream
Who wants to wager that meal has more calories than a Big Mac dinner?
Noting that people like to eat unhealthy foods doesn’t contradict the observation that they also like to be healthy, of course.