[Reincarnate]

Perhaps:

"Dirty" foods = foods that can be abused easily, often found in significant proportions in the diets of most overweight, unhealthy people.

There's nothing inherently unhealthy about, say, pizza -- but it's real easy to blow your macros and overeat, which can lead to obesity and health problems, etc.

It's harder to overeat if your diet is composed of satiating foods with low caloric densities.