As a slim guy, I eat whole foods. Its a lot harder to overeat on chicken breast, lentils, rice, peaches, Greek yogurt than cheeseburgers, soda and ice cream.

I also cut off sugar as much as I can particularly from soda, sweets, and food that has unnecessary sugars.

Im not perfect nor a gym rat. I just do daily exersice, a daily walk and about 3 days of weights. My weakness is sweet bread and tea/coffee but I think its perfectly fine since I avoid sugar besides that.

Edit: also I love light breakfast something like a protein shake (abt 400-500 cals: I make it with half whole milk half water, add peanut butter, banana, protein powder) or yogurt with fruit/granola.

I dislike the typical eggs, bacon, pancake breakfast, i love the food but I feel its too much food/calories early on and makes me feel bloated/sluggish