As we talk about how hard it is to combat obesity, it’s worth thinking about numbers like this once in a while. If we could get kids to give up half, not even all, of the added sugar in their diet, their overall calorie consumption would drop by 8%. They’d be dropping about 140-180 calories a day from their diet. And those calories are totally empty – they’re from added sugars they don’t need, and that won’t satiate them. When other research shows that reducing your caloric intake by 20 (yes, twenty) calories per day for three years could lead to an average weight loss of 2 pounds, making this small change could be a big deal.Okay, there is a good point here and a really bad point here. The good point is that added sugar seems to be a bad thing. It promotes tooth decay (with 2 root canals, I can say that this is a big deal), it seems to be efficiently absorbed, it is associated with diabetes (a disease you really do not want), and it's nutrient value is null.
But the idea that a 20 calorie a day change will mechanically lead to a 2 pound weight loss in 3 years is kind of odd. I mean it works, mathematically. But it ignores all sorts of issues: like how does the body adapt to less intake, what foods are eaten (is it the same composition with portions shrunk by 1%?), and how this may alter activity levels. The claim makes something that we know is hard sound very, very easy.
Programs like Weight Watchers seem to partially get good results by restriction, but they also seem to have incentives to change the composition of the diet. Just look at how fruits and vegetables can be zero points in the current diet.
So, in an odd sort of way, the last point detracts from the main issue here: added sugars are bad and trying to expose your children to less of them is unlikely to be a bad thing.
I'm disappointed to see this kind of thing coming from Carroll (who generally does good work). It reminded me a bit of this
ReplyDeletehttp://andrewgelman.com/2012/02/confusion-from-illusory-precision/