This is just on the top of my head, but since obesity is one of the leading causes of death, coupled with the stigma of getting into relationships with obese people, in the far future the genes somehow responsible for obesity would be gone. Those who would survive and pass on their genes are the normal or at most, overweight ones.
Masking. Not really for hygiene reasons. As an introvert, it made me less shy. I feel naked going outside without one.