Humans evolved to crave sugar, fat and salt ... our ancestors' very survival depended on it.
And that's what is driving the nation's obesity epidemic.
"There's nothing broken with the biology. It's working perfectly. In fact, it's working too well," said Dr. John Peters, an expert at the Colorado Center for Health and Wellness, part of the University of Colorado.
The real problem is that our civilization shifted the human condition from one of scarcity to abundance.
"So now we're suffering the unintended consequences of all of that progress," Peters said.
If gaining weight is bad for your health, simply stopping the gain can be a big benefit.
"We know that as your weight increases, all kinds of bad things happen--diabetes, heart disease, whatever," said James O. Hill, the head of the Colorado Center. "So even if you're overweight or already obese, simply not gaining any more weight is a step forward and will reduce the chances of your health getting worse."
Dieting may not be the best option for some overweight or obese individuals.
"I definitely think there are times in our lives when we're ready and able to do that, and there are other time when you've got so much going on that you can't make it a priority and those perhaps aren't the best times to try to lose weight," said Dr. Holly Wyatt of the Center for Human Nutrition at the University of Colorado.
Picking and sticking to a diet is key to losing weight. Exercise is more important later, after the first six months, since it's key to keeping that weight off.
Wyatt and Hill are members of the team behind the National Weight Loss Registry, which seeks to gather information from people who have successfully lost weight and kept it off. They've found that individual success stories share similar practices: the person eats a lowfat diet, weighs himself or herself daily, and exercises regularly.