American shoppers can acquire 210 calories of food for every calorie they expend doing it. Hunter-gatherers found nine calories, while early farmers raised 53 calories for each one they expended.
It all boils down to human beings having "thrifty genes" and our past environment favoring those that could get the most from calories and burn them the slowest.
"With a genetic heritage exquisitely tuned to the food scarcity of the Paleolithic era, a bonanza of cheap, high-calorie 21st-century food, and a society designed to minimize physical exertion, some believe it's a wonder we're not all obese and sick."
I think this sentence explains the obesity epidemic as well as anything else I've read and I've been doing a fair amount of reading on the subject.
Our bodies were meant to move and we were never meant to eat this way. That's where the self discipline comes in. We can't change our environment any more than we can change our physiology. We can only change the way we as individuals relate to these circumstances. I plan to keep moving and stay away from the junk food. I would urge everyone else to do the same or accept the consequences of falling into the trap evolution has set for you.