Food wise? Oh that's easy.

Fats and salts, before agriculture and animal domestication, were hard to get a significant amount of in our diets, and the plants we foraged were usually much lower in starch and higher in fiber. Our bodies are geared to focus on these nutrient sources, so starches fats and salts taste really, really good.

Agriculture short circuited that focus as we produced and cultivated plants that were starchier, sugarier, and animals in general tripped our 'mmmm delicious' buttons much better than their uncultivated ancestors.

So basically it's REALLY easy in our modern diets to get WAY too much starch, salt, and fat because our appetites are geared by millions of years of evolution but we have only been agricultural for a hundred thousand years at the very most and our biology hasn't caught up.

So we take in a LOT more of the 'good stuff' that our body wants, and too much of anything is not good.

Hence the modern obesity epidemic and the rise of type 2 diabetes.

People like to whine it is a personal willpower problem, but it really isn't.

It's a food supply problem. 60% of the space in our grocery stores is just made up of various nutritionally empty configurations of starch, fat, and salt.