I believe it's a often a combination of the above.^
Most morbidly obese people live off a diet of processed food. Very few lead active lifestyles. It is unfortunate how many Americans are severely overweight, we definitely have more than our fair share of fat people in this country...
There are people with a genetic predisposition towards obesity or with medical issues that may affect their weight - they are in the minority and I do feel bad for them. The vast majority of fat people simply eat too much of the wrong food and don't exercise enough!
There's only one naturally produced beverage with more antioxidants per unit than coffee, and that's tea. Coffee (aside from the TERRIBLE HORRIBLE... mild stimulant it contains) is actually great for you. It's all the crap people add to it that makes it bad for you.
And please don't lump starbucks in with Mac D,s. You know what's in starbucks iced coffee? Coffee... well with iced added to cool it in a timely manner. Add vanilla? Vanillin and sugar added. Plain sweetner? Sugar and citric acid. Anything with milk? Nonfat milk, 2%, whole, half and half or heavy cream... it's up to you (forgot soy). People give starbucks crap, but the quality of their ingredients can't be questioned.