Don’t forget the big one, carbs. Carbohydrates are fairly hard to find in nature, even if you have a carnivorous diet and you get plenty of fat and proteins, you will desperately crave carbohydrates which are easier for the body to convert to energy than just fat by itself, and most animals were pretty lean so you would be very lucky to even get a lot of fat in your diet to begin with. If you just eat lean meat you will die.

Fruit, starchy tubers, honey and other natural sugars were prized sources of energy, this is why we love sweets so much and why a package of oily french fries feels like heaven, you are responding to natural imperatives that still think you’re at risk of starving.