The notorious "calories in, calories out" is so unscientific and is in my view a criminal oversimplification. It ignores things like epigenetics, hormones, thermogenesis, metabolic diseases, digestion problems, microbiota, etc. Yes, counting calories can give you some rough idea about things, but it's so rough that it's useless for the purpose of dieting! Calories from fats and carbs don't get metabolised the same way either! When I see MDs giving such advice, I smell quackery! I cut my dietary intake by over 1,000 from fats (I was putting ghee and MCT/coconut oil in my coffee) without actually compensating or expending less energy. I didn't lose a gram of weight!