The amount of energy a person can consume throughout the day without gaining weight is extremely dependent on

True, because the activity you do throughout the day burns all that fat and calories you gain from eating, and if you have a balanced meal and practicing activities/exercises, you shall not gain weight even when consuming a lot of food, as long as your activities/exercises is balanced with it :-) 

The amount of calories they expend, for example a person who is a runner can eat more calories than someone who is sedentary.

Dairy, grains, protein, fruits, vegetables

Trade schools would be the best option