People with higher education often take better care of their bodies. Here is my theory: A couple of decades ago, IT didn't require much education, because there weren't many schools doing IT. So many people without higher education worked in IT.
edit: and I believe every fat person, knows and knew, that being fat is bad, but when you are sad and eating is your allmost only joy, what can you do? Starving and give up that little bit of happiness?
Maybe I'm a good example, because I used to be rather overweight (125+kg) and inactive. After I started working in IT, I've slimmed down to below 100kg and I've been doing crossfit for ~5 years.