How about volume of food consumed, energy density of food and digestibility of foods. Train on low energy density foods with low digestibility (rate of digestion) and switch to high energy density food, with high digestibility and you will get fat ie you continue to eat the same volume of food more often to sustain the same sense of fullness and hence you store much more fat.
As for cooking foods to enjoy a healthier and tastier diet, what craving do you miss the most, that lazy ass one where you do not have to get up and do all the prep and all the cooking and all the serving, just wrip, drop, bing, plop, all in minutes. Pretty much the less effort you put into food the fatter you will likely become and the more work you do in order to obtain a meal, the thinner you will become. So in the city, walk 2 km to the store, carry you raw ingredients back and than prepare them and then eat them. Double plus, huge limit in snacking as a snack, unless it is leftovers, can take a couple of hours and whole bunch of effort, snack (no leftovers), meh, maybe later and you basically keep putting it off until it is time for a proper meal (I do admit, you tend also to become much more skilled at left overs).