What are the main reason obesity is such a problem in the US?

Dont be anti-american plz

American food is enriched. You put vitamins into everything. Junk food culture rules. People don't work out and spend too much time watching TV or playing Video games and not outdoors. SO its all a matter of bad habits and society imposed wrong activities.

Because people are not exercising, not drinking enough water and not eating nutritious foods.
Eating too much mcdee's.
the stuff we eat are full of chemicals. half of us are too lazy to work out. when were sick. we take drugs. most of us would rather eat tastey then eat healthy. even our groceries carry chemically produced fruits and veges. the stuff at micadies and taco bell are not healthy. even when its salads. (reason is because they soak lettuces and other veges in some chemicals to make it last longer, i should know, i used to work there)
because people are lonely and they substitute food to satisfy their loneliness.
Too much junk food. Too many people hopping into their SUVs to drive two blocks instead of walking.
fast-food & too much technology. ppl dont do stuff for themselves anymore. they have "technology" do it for them.