As a species we evolved eating saturated fat, cooked over an open flame, and without access to a globalized network of food distribution providing us with arugula mid-winter.
It is true however that we are out of balance with nature. Our ancestors had to expend many kilocalories gathering and hunting food. Today we simply tear open a bag of Cheetos or have Chinese delivered; calorie consumed: 1500, calorie expended: three.
That’s how we have gotten fat and depressed.