With two thirds of U.S. adults overweight, it doesn't take rocket science to conclude we don't have a clue about how much to eat.

But now there's a countertop gadget that looks a little like a kid's cooking set - perhaps not for nothing - that is meant to help with portion control.

It's called Lifesize and was created by Myles Berkowitz, who was fed up with being overweight, and his trainer, Stephen Kates.

"You have to eat less food - that's the whole secret," Kates says.

"Don't change what you eat; change how much you eat" sums up the idea behind Lifesize, a set of plastic measuring vessels marked for meats, toppings, saucy dishes and other categories of food.

Six portions per day, same for men and women, plus a snack are allowed. Fruit and vegetables generally can be eaten in unlimited quantities.

Lifesize launched last year and is available for $79.99 online at lifesizeportions.com. It includes the containers, a chart, videos and other information.

Berkowitz, a filmmaker, says he had had it with his weight and his poor health when he went to seek help from Kates, who has a studio in Santa Monica, Calif.

But Kates didn't reccommend going on a starvation diet and cutting out all the foods Berkowitz had been enjoying, to obvious excess. Instead, the trainer had some welcome news for Berkowitz.

He told his new client he didn't need to limit his consumption of his favorite foods, such as ribs, to twice per year. He could have ribs whenever he wanted; he just needed to limit the amount.

Kates' theory was based on decades of observing people who seemed to eat whatever they wanted without developing weight problems.

Berkowitz says he was more than skeptical and thought portion control was too complicated. But he gave it a try, making clay containers to figure out the right amounts of various kinds of food. The system worked.

He got to eat plenty of the food that he wanted and found he was satisfied. And he lost 46 pounds that he's kept off for five years.