Mod to high SES is correlated with eating healthier food, we all get that. However, by convincing low SES to eat healthier, you can actually increase their SES

Mod to high SES is correlated with eating healthier food, we all get that. However, by convincing low SES to eat healthier, you can actually increase their SES. For example, if you eat better, you are healthier and therefore take less sick days at work. If you don't get paid for sick days, this means more money in pocket. Showing up for work more may increase your chance at a raise or promotion and therefore increase your SES. So I think there is value in these studies. As well, food diaries are a standard measure of diet. Not ideal, but accepted standard.