Sometimes it takes a scientific study to point out what should be obvious to common sense:
"The main cause of the obesity epidemic in this country [the US] is the wide availability of high-caloric foods and the fact that we are eating way too many calories in the course of a day. Exercise has much less impact."
"...about 90% of weight loss is achieved by cutting calories; only about 10% of weight loss is achieved by significantly increasing physical activity."
Eat less. Lose weight. Any questions?