Have your blue jeans gotten too tight and your tummy too rotund in spite of your consistent efforts to choose the least fattening items on the menu? If you’re dining out at Ruby Tuesday’s, Applebee’s, the Olive Garden, Denny’s, Wendy’s, Dominos, or any of 29 popular chain restaurants, you might be able to blame inaccurate calorie counts for tilting the scales. In other words, the menu says you’re only getting 490 calories, but the meal actually contains 600 or more.

A recent study out of Tufts University, just published in the Journal of the American Dietetic Association, found a significant discrepancy between calorie counts listed on menus and the actual calories contained in the meal. Staying home and popping a frozen low-cal meal in the microwave won’t solve the problem either, because the researchers also found that many frozen foods don’t match their purported caloric content.

The average restaurant entree contained 18 percent more calories than the menu claimed, the study found. “Those don’t sound like huge numbers but that really adds up over time,” said study director Dr. Susan Roberts. Suppose you order an item that’s ostensibly 500 calories, but the 18-percent factor adds 90 extra calories that you don’t count. If you do that every day, adding on 90 extra calories daily, your waistline will register the difference in short order. And if you eat out several times a day relying on posted but inaccurate caloric counts, you’ll certainly find the pounds piling on faster than they should be. “It’s the difference between maintaining your weight and gaining 10 pounds,” Dr. Roberts says.

In some of the restaurants reviewed, the discrepancy between advertised and real calories far exceeded the 18 percent mark. For instance, the healthy-sounding grilled-chicken wrap at Wendy’s, touted as having only 260 calories, actually tested at 344 calories. A serving of grits at Denny’s weighed in at 258 calories, though advertised at only 80 calories. And at PF Chang’s, Sichuan-style asparagus measured 558 calories, more than twice the 260 calories listed on the menu. Plus, the posted calorie counts usually only apply to the main dish. Side dishes and condiments can double the calories. In fact, Dr. Roberts found an average of 471 calories in the side dishes tested. People don’t realize that the calorie count applies only to the entrée “What they should be telling consumers,” Roberts says, “is what actually comes on the plate.”

The restaurant professionals claim that their calorie counts can’t be 100 percent accurate given the realities of food preparation. A spokesman for Wendy’s, Bob Bertini, explains, “Since our food is handmade, there can be variance in calorie counts. One sandwich may have more mustard or mayonnaise, the next may have no lettuce or tomato.” And yes, Bertini makes a good point, although it’s hard to imagine that the addition of a tomato or a smidgen more mustard could account for an 80+ calorie difference.

On the other hand, to be fair, several of the items tested actually contained fewer calories than listed. A slice of Domino’s thin-crust pizza, for instance, contained only 141 calories instead of the expected 180. Still, remember, the average entree tested came in 18 percent above the advertised calories.

The 12 frozen diet meals tested, including samples from Lean Cuisine, Weight Watchers, Healthy Choice and others, performed better, with an average of eight percent more calories than the label said — not quite as dire as the restaurant differential, but of concern, nonetheless. Lean Cuisine’s shrimp and angel-hair pasta was a standout: the label says it has 220 calories, but the researchers measured it at 319. As Dr. Roberts points out, consuming even five percent more calories in a 2,000-calorie diet adds up to a 10-pound weight gain over the course of a year.

How do food providers get away with advertising significantly fewer calories than reality bears out? Apparently, the FDA allows a 20 percent fudge factor in packaged food calorie counts, although when it comes to weight, products must be 99 percent accurate in labeling. Why is the 20 percent discrepancy tolerated? Is the “close-enough” mentality a reflection of the fact that people coming out of school can’t count so they just take a guess? Or is it what Dr. Roberts thinks: “The FDA regulations are much more punitive, much more stringent on under-providing than over-providing. It’s an old-style mentality: ‘People need to be given what they pay for,'” she says.

Meanwhile, the federal government doesn’t regulate the claims made by restaurants. That’s up to states to do. The researchers concur that state regulators often don’t bother, since they have more important things to do, like checking the kitchen for mouse dung and cockroach parties. In other words, though it’s a great idea for restaurants and food manufacturers to reveal caloric content, you’d better not trust labeling 100 percent. If you really need to lose weight, keep that in mind, and follow Dr. Roberts’ advice: “If you want to lose 10 pounds, you can do it with [restricting] food. [Restricting] food is the best way. But by eating at home, you’ll have a much easier time.” And to that I would add, yes, eat at home, but eat freshly prepared foods rather than those convenience diet meals. And as always, I recommend buying a set of dinnerware that uses 10-inch dinner plates (the old standard), not the current 12 inch standard. Those extra two inches actually double the surface area of the plate — allowing you to double your calories while making it look like half the food.

:hc