Food prep takes time. Even if we abandon looking at it as as a strictly energy in energy out situation, we probably still recognize that healthier foods take more time than unhealthy foods.
>Even if we abandon looking at it as as a strictly energy in energy out situation
There is no reason to abandon looking at it that way. Eating healthier will not result in you losing weight if your caloric intake remains the same. Feel free to continue eating $1 burgers, just eat fewer of them.
Read an interesting piece here on HN that suggested weight had other, perhaps more important elements, and that consuming fewer calories while using fewer of them was the symptom of something else. Sort of rocked my world because I had always sort of accepted/repeated the argument from thermodynamics and it really upended that world view.