When you buy a car with a six-cylinder engine, you expect to get six cylinders. When you buy a dress in a size 10, you expect a size 10. And when you buy a burger at a fast-food joint that's listed on the menu as containing 500 calories, you jolly well expect 500. But you may be getting a lot more than that. The same may be true of the omelet and the pasta you get at a sit-down restaurant -- and of the frozen dinner with the label you read so carefully before you tossed it in your supermarket basket and took it home. (See the 10 worst fast-food meals.)
According to a new study published in the Journal of the American Dietetic Association, prepared foods may contain an average of 8% more calories than their package labels own up to and restaurant meals may contain a whopping 18% more. Worse still, as far as Food and Drug Administration regulations are concerned, that's perfectly O.K. (See the top 10 new diet books.)
The findings are the result of work conducted by Susan Roberts, professor of nutrition at Tufts University, and Jean Mayer, of Tufts' USDA Human Nutrition Research Center on Aging. It was Roberts who initiated the study, and it was her own struggles with weight that got her started. Author of the book The Instant Diet, she was working on new recipes for the paperback version (retitled The "i" Diet) and, as was her practice, used herself as a guinea pig. As a rule, she lost weight on the menu plans she recommended to readers, but when she redeveloped some of the meals using what were supposed to be calorically equivalent supermarket or restaurant foods, the pounds stopped dropping off. Just as suspiciously, she always felt full.
"I went into the lab and said, 'I don't believe these calorie numbers,' " she says. "So we went out and started collecting foods and sampling their contents." (See 10 myths about dieting.)
In all, she studied 29 restaurants and 10 frozen-food products, taking care to select foods that dieters would be likely to choose, which meant that they were said to contain 500 calories or fewer and that, in restaurants, they were among the lowest-calorie items on the menus. Back in the lab, Roberts' tests revealed the high-calorie truth, and the numbers were even more troubling than ordinary dieters would appreciate.
No one would deny that the 18% calorie overload on restaurant menus is a problem. The additional 8% in frozen foods sounds less serious; in a 500-calorie entree, after all, 8% adds only 40 calories. That, however, is in a single meal. Over the course of a year, consuming just 5% more than you need in a 2,000-calorie diet can mean a 10-lb. weight gain. "The 18% and 8% figures are just what you need not to lose weight," says Roberts.