Those conducting this study claim that it does--that if you shop at some upscale grocery store and spend more money there, you will be thinner than those shopping on the cheap at the grocery store in a poor neighborhood because of the healthier foods sold there.
I totally disagree, for these reasons.
#1 CORRELATION does not mean CAUSE. Sure customers wearing tweeds at the whole foods market tend to be thinner than those shopping at Wal-Mart. But that is because obesity is to an extent a class-related phenomenon. People who are wealthier regard obesity as a disease, and having more money they have all kinds of options for treating it or avoiding it. (If you can swim in your pool and play golf twice a week, you are gloing to be thinner than someone whose idea of recreation is stitting on the sofa watching TV and chugging beer or soft drinks.) Poor people on the other hand regard obesity as an everyday fact of life; they have fewer choices for recreation and healthy living, and are more likely to eat out of boredom or depression. Poorer people are also less educated, and less informed about food choices.
#2 Eating cheaply does not have to mean eating junk foods. Yes, cheap hamburger has more fat. But many cheap foods are good foods. For example, dry beans and peas, which are about as healthy as anything you can buy at any price. Brown rice is not too expensive. Chicken breasts you can buy for under a dollar a pound; you can peel off the skins and freeze the breasts until you are ready to pop them out, defrost them in the microwave, and prepare them. Breasts are much healthier than thighs or drumsticks, and cost only a little more. You can find a can of salmon on sale for about $2 and a little can of tuna for $.50-.70. Cans of vegetables you can buy on sale for $.25-.35 per can; granted that these canned veggies have salt added. You can normally find good fruits and vegetables on sale at the local market.
There is no reason to think that you have to spend more to eat better!