HOUSTON -- It's hard to buy food without some sort of sign about zero transfat, zero calories, less fat, fat free, etcetera. But what appears to be a beacon for those looking for healthier food may be offering a false message, KPRC Local 2 reported Wednesday.

Consumers have become savvy about the fat and calories in food. But Jeff Novick, an expert from the Pritikin Longevity Center, said we need to be even savvier to the tricks being played in supermarket aisles.

He said Americans are getting fatter because food labels are misleading.

Take milk, for example. The label says 2 percent, but Novick said that is not even close.

"What they don't realize is that's 2 percent by weight. That product is 36 percent calories from fat," he said.

Novick said a walk through the grocery store would find all sorts of creative math and marketing for dozens of low-fat items.

A can of condensed soup said it is 89 percent fat free.

Yet, when Local 2 checked the nutrition facts, a serving delivers 60 calories -- 25 from fat. That's roughly 40 percent fat per serving.

So, how did they get 98 percent fat free?

"You divide the weight of the fat by the weight of the serving and you come out with 2 percent fat by weight, which is the equivalent of 98 percent fat free by weight," Novick said.

A Campbell's Soup Company spokesman said that it is not creative math. It uses the standard set by the Food and Drug Administration and the United States Department of Agriculture.

Campbell's said the labels are reviewed before they are shipped.

Novick said the numbers are technically true.

For instance, Pam spray-on oil requires a quarter of a second spray to get a fat-free serving.

"There you go. Now how many people do that? Most people just (let) it rip. So, people sometimes ask me, 'How do you really get a quarter gram out of that?' And I tell them, 'Here, just leave the lid on and wave it over the food.' Now you and I are laughing, but we know," Novick said.

Obesity in America is on the rise -- 64 percent of adults are overweight or obese.

Novick is convinced the government's math is part of the problem.

"So, every day in America, thousands of people are buying products and they're not sure of what's going on," he said.

Marketing is another problem.

Many products labeled as low fat may be high in sugar or salt. Those low in sugar may be higher in fat or cholesterol.

Novick said the best way to fight back is to ignore the advertising on the box and look at the list of ingredients.

For more on the Pritikin program, visit www.pritikin.com.