Its many things lack of education lack of money, lack of excercise,being epxosed to massive advertising the fact that you can go to a grocery store that has entire rows devoted to chips,cookies and other foods made with trans fats the cheapest way to make these things.They force you to go thru these rows just to get some milk or vegetables.Also we have become really lazy and dont want to cook its all about convinience.And a lot of people just dont eat vegatables,they just dont appreciate them because they never really ate them when they were kids, I suppose.Refined foods is another problem no one seems to want to eat food in its natural state.Then heres another issue people eating because of something missing emotionaly to fill a void in their lives.I think America has alot of depressed individuals I also believe if you are raised on bad food then thats all you know so thats what you eat.I also believe rather then having a sweet tooth alot of people developed a fat tooth fat which is also really addictive.