There are drugs that say otherwise. As a side effect of medication, I've had to increase my calorie intake to maintain my weight.

Not to mention the relative bio-availability of foods differs even when their calories don't. Fats and Proteins need more processing per calorie than Carbohydrates.

I'm also fairly certain there are limits to the human bodies ability to absorb calories. i.e. you could saturate your diet by eating way too many calories, but your eventual weight gain would be at the limit of your body's ability to store fat.