Obesity is the most noticeable one. When I was a child, there were very few obese people. There were a couple of boys in my primary school whom we all considered "fat" but by today's standards they would just be a bit overweight.
My mother used to talk about her mother being "too fat" and I remember her buying her mum a dress for her birthday in a size 18. That was in about 1971, when sizes had smaller measurements than they do today. I'm guessing an 18 is probably about 14 nowadays. My gran was quite tall, taller than my mum who was 5'3", so wasn't "fat" by today's standards.
Nowadays, from casual observation, it seems that about 75% of the adult population is either overweight or obese.