It isn't often that I refer you to an article in full that has been written by someone else, or in this case, a couple of someones. You can trust that I am doing it for a good reason. The article published in the NY Times addresses a point often made here. Headlines and research should be interpreted carefully.
I believe that these two journalists get it exactly right (one hails from Union College - yay). I only have one or two things to add, but I really think you should read the article first... click HERE.
Okay - I feel like you didn't listen to me. The article is about junk food advertising and soda sizes causing obesity. Read it HERE.
The only big problem I had was with the journalists' assertion that we do not know what causes obesity. Of course we do. A lot of people eating more calories than they need (and the number they need is personal). There are reasons that people eat more calories than they need and some of those reasons are ones that I want to study. I want to use the exact type of research design that the journalists advocate. But, I do not think randomization into conditions will always (or ever) be possible. Lagged interventions, or lagged policies may allow me to make good inferences. By this I mean, if one state adopts a public health policy before a similar state does, I can compare the two states on the outcome (calories purchased, BMI, etc). Most of the time, my work will speak to associations, relationships, correlations and that is ok. I hope I can get to cause, but I won't pretend that I did when I did not.
I would reword some of the journalists language about the studies they referenced. It is true that advertisements do not cause weight gain - but they may entice people. Ads may lead people to establishments where they over consume. Once inside the restaurant, is there any hope? Maybe. It is possible that putting the number of calories per item on a menu might encourage people to chose an item with fewer calories. Having to put calorie numbers on a menu might encourage the restaurant owner to offer more low calorie items.
Having less billboards, less fast food places, higher prices on nutrient poor foods, removing sodas from WIC and SNAP benefits...Polices like these might reduce consumption of foods that are very high in calories... but at the end of the day.. it will always be about a choice that a person makes. If that choice includes too many calories.. weight gain is likely to follow.
(ps if you think that the government wants to manipulate you and the food industry doesn't, you are woefully naive)