We are always responsible for keeping ourselves as fit and as well as possible.
Of course we live in a high pressured society and so some people use indulges in order to change mood, coping strategies can become self defeating, and some confuse feelings with hunger.
Also, some conditions like arthritis and general wear and tear can interfere with life choices as to how we'd like to stay fit.
We also live in a culture where hidden sugars are not often revealed in certain foods. Many foods are processed, pumped with hormones etc and not everyone has the finance to buy fresh. Sugar alters mood, as does drink and cigarettes.
And where there is money to be made in the self defeating cycle of being overweight and unfit, personal trainers, gym membership, lose weight clubs, and foods, (which leave you hungry), fad diets, exercise DVD's while advertising sugary, fattening foods.
This is a comsumer culture and they want us to consume
to keep the economy running because we live in a debt and credit society. We are always working to pay of the debt the banks have got us in by lending money they don't have.
If we were all healthy what would they sell us? How would they make money to pay off debt?
It certainly isn't clear cut O_o