I think not enough has been said for the neurobiology of food. A lot of modern foods (high processed) have been engineered to maximize food rewards using a mixture of salt, fat, carbohydrates, and proteins / amino acids / MSG. These foods tend to be highly calorie dense and extremely rewarding / addictive while at the same time producing low satiety (so you don't feel full and want to keep eating).

Doritos is the classic example of this.