With respect, I think you're ignoring the facts. How it's prepared absolutely makes a difference in how it tastes, how easy it is to eat, etc. and there is a resulting effect on how much people eat.

Freshly grilled chicken and frozen chicken patties are both chicken. But the chicken patty is ground, pre-seasoned, pre-cooked, etc. This makes it easier to get ready and easier to eat than a fresh chicken breast.

The poison is in the dose, as they say. 500 calorie surplus every day is a pound a week of weight gain.

And as dieticians have shown us over and over again, you can eat shitty food and be healthy, you just have to eat an appropriate amount of it. There are diets based on cookies and snack cakes, if you eat at your maintenance and cover a few basics with supplements, you can easily thrive on them.