You're likely mixing fat with carbohydrate. When you combine fat+starch+sugar, it signals your brain to overeat. You turn a simple potato, which is very low calorie and very filling per calorie, into a monstrosity by slathering it in butter, cheese, sour cream and/or bacon. That'll send your hunger through the roof and your brain will signal the body to overconsume to prepare for "a famine." Except the famine never comes in today's America.
You're forgetting carbohydrate is less than half as calorie dense as fat. It may take a lot more "volume" of carbohydrate to get the same sated effect as fat.
I don't advocate exclusionary dieting. Health problems can and often arise from extended periods of too low carbohydrate or too low fat. However, what's a great idea is separating your fats and carbs. I always prioritize protein since it is non-fattening and the most filling macronutrient. After that, I center my protein around fats OR carbs, but not both. This way, you can live a lifestyle that is balanced in macronutrients and prevent overeating by making your meals either low fat or low carb on an individual basis.
I doubt you're overeating boiled potatoes and steamed chicken breast. I bet you'll eat more fried sausage and sweet potatoes, though. That's a food reward nightmare.