The reason so many Americans are obese is simple..too much sugar and carbs! For me personally i did the whole yo yo dieting thing for years and tried the low fat low cal diets, but for my hubby..he never yo yo dieted, he never did low cal or low fat..and he ended up weighing 340 lbs by age 29!! Then he went on Atkins and lost 90 lbs bringing him down to 250 lbs (which is barely overweight for his height of 6'5"). After a couple years he has now decided to continue on and lose ALL his body fat so he is back on atkins shooting for 215 lbs. Anyways, he is an example of someone that got obese simply by eating a bunch of fast food, sugar and carbs!