The food-scarce environment of our ancestors likely led to humans' propensity to gorge when food is available and to crave high-caloric foods—a trait that might lead to an epidemic of obesity when food is plentiful. this illustrates how:

This setting will no longer happen for people nowadays are much conscious with their health and that people would not think of food scarcity, for all types of food are made available and that various fitness gym are everywhere. Being obese is lack of self-control and eating healthy diet is always choice. Therefore, evolve mechanisms are not always adaptive in modern society.

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.