The vast majority of obesity is caused by poor diet (in part due to our food supply, in large part also due to our choices) and lack of exercise. The major cha

The vast majority of obesity is caused by poor diet (in part due to our food supply, in large part also due to our choices) and lack of exercise. The major changes are: food supply (more addictive, more calorie-dense, etc), more sedentary lifestyles (tech creating mass convenience in everything from shopping to traveling to entertainment, etc), and individual choices (influenced by both the above, but also increasing acceptance of obesity, mental health, etc)