Fast Food and Obesity

Obesity and fast food is there a correlation, probably. Imagine that fast food might make you fat. Don't get me wrong I don't think fast food companies should be sued for peoples obesity. Maybe they should be encouraged to make their foods a bit healthier though. Another option may be to require some sort of payment by the fast food companies to cover the rising costs of health care caused by obesity. Something like the tobacco companies are required to do. What are your thoughts on fast food and obesity?