You would have good reason to suspect that.
There are large pay gaps between "tall" and "short" people, which presents a significant reproductive advantage to the taller people-- at least in terms of the social hierarchy of human society. (There are caveats-- more successful people tend to have fewer children, due to better education. It needs investigation, but being suspicious is good.)
However, the foods people eat (and prefer to eat) is not based on "Sensible and good for you." If so, people would munch down on high fiber leafy greens all the time.
Usually, the foods that are most popular lie at the intersection of "Inexpensive to produce/obtain" and "Has lots of calories, or salt."
Things like-- Bread. Pasta. Potato chips. Candy. Soda. etc.
People LIKE these things, because in the not so distant past, high calorie yield foods were rare, and consuming them helped you put on fat, which helped you survive naturally occurring food shortages. (or because they contain substances that are uncommon in concentrated forms, like salt.)
People buy these more often than other foods because they are cheaper to produce (due to economies of scale and other factors, such as shelf life) than other foods.
The combination of "Tasty" + "Cheap" produces a routine diet that then becomes culturally reinforced.
Before you know it, you have the Supersize Me! generation.
Sure, Eugenics could help fix this by making high fat, high carb foods taste bad, causing people to preferentially reach for that fresh kale instead of that bag of chips... but that is not the kind of thing I would expect from a eugenics proponent. Rather, I would expect them to introduce new variants that alter the way you put on weight--- and as such, make it so that people will starve to death if they dont binge on the calorie rich foods, due to defective fat storage genes. They would market this as "Your kids can eat whatever they want and will never be obese! Isn't that GREAT!?"