The idea that an epidemic can suddenly appear based 100% on personal choices is the stupidest thing I've ever heard.
For the record, while
individual cases of obesity (including my own) can be partially attributed to personal choices, the massive rise in obesity in the past couple of decades is a combination of increased car usage, a lessened need for physical activity both inside and outside the workplace, the corporatization of agricultural production and distribution, and government subsidies that benefit dairy and corn rather than vegetables, thus making the latter more expensive in relation to the former--it's not like people suddenly lost the ability to make healthier choices.