Obesity - a silent epidemic?

Obesity is a national epidemic here in the USA. I'm just curious to know why the world's only remaining superpower has one of the highest obesity rates in the world. Is it due to lack of physical activities or due to overeating? The cause of obesity is due to combination of both.
Let me first explain first, about diet. Over the past two decades, our foods have become much richer in both fat and calories. Another problem is the serving size. The foods being served are enormous in quantity. The rise of fast food chains is also one of the leading causes of obesity. A small sized french fries has approximately one hundred calories. Junk foods does nothing to our nourishment other than satisfy our taste buds. Food being served in schools are also saturated in calories. The use of whole grains foods is rare nowadays.

Secondly, our lack of exercise. We have drive-throughs at most of the places we go: banks, fast food chains. There are elevators in most buildings. People are so busy in their life that they can't make time for exercise. Kids spend more time playing video games and watching TV. The concept of playing outside is becoming rare now. Exercise has beneficial effects not only on our physical health but on our mental health too.
Solutions to fight obesity is a bit challenge but if each us contribute , I believe we can solve it. There are no magic bullets like diet pills. Losing weight by keeping to a strict diet can be successful but the problem is that we will regain all the weight, once we break the diet. We have to watch the portion of our servings. Always know the calorie content of the food you eat. Try to eat fruit instead of ice creams or cakes for desert. Drink water instead of juice or soda.
Avoid using drive-throughs, escalators or elevators. Try to walk if the destination is only 3 blocks or less. Recent studies have shown that diet is more important in losing weight than exercise.
Let us all fight this epidemic together.