Studies are confirming what you already knew intuitively: "Check, please" are two of the most fattening words in the English language.

The more you eat food prepared away from home, the less healthful the meals, the more calories you consume and the heavier you become. Researchers at the University of Memphis drove home the point when they reviewed a week's worth of food records for more than 100 women. Those who ate out--or bought takeout food--at least six times a week consumed, on average, 300 more calories a day than women who relied more on food from their own kitchens.

A separate study, conducted by the California Department of Health Services, found that people who eat out consume up to 25 percent fewer fruits and vegetables than people who prepare all their meals at home. And investigators at the Energy Metabolism Laboratory at Tufts University in Boston this month published an investigation indicating that people who eat out most frequently have greater body fat because they are eating more calories and fat and less fiber than other people. The association between eating out and body fatness is "robust," the Tufts researchers say.

Once upon a time, overdoing it when eating away from home didn't present much of a problem, because dining out was a rare event. "It used to be that Americans ate out for Mother's Day, birthdays and anniversaries," says Hope Warshaw, an Alexandria dietitian and author of "The Restaurant Companion: A Guide to Healthier Eating Out" (Surrey Books). "Today," she notes, "eating out is just a part of life. But we haven't shifted our mindset about how we think about restaurant meals. We still think of them as an opportunity to splurge. That was fine and well when it was four times a year. Now it's four times a week."

Perhaps ironically, some restaurateurs are seeing it the same way. "Eating too much was always part of" eating out, says Nora Pouillon, chef and owner of Restaurant Nora in Washington. "Since it was only occasional, you could catch up the next day," by eating less than usual or doing some exercise, for example. "Now," she comments, "people eat out or buy prepared food every night. The portions are too big, and they still eat like it's only an occasional thing."

Indeed, restaurant portions are even bigger than they were in the days when Mom wore a corsage to her Mother's Day meal at the local upscale family restaurant. "Both plate size and portion size have steadily increased through this whole decade," reports Jonathan Locke, a partner in FoodSense, a Minneapolis-based restaurant consulting firm. Even if you order the low-fat entree, he says, "if you're getting two wheelbarrows' worth, you're going to pack on calories."

It's often said that restaurants are to blame for the ever-larger portions and should help people eat less when they eat food prepared away from home, perhaps by serving smaller portions for lower prices. But dietitian Warshaw says that in the end, it goes back to the patron, not the restaurant. "As long as consumers equate volume with value," she points out, "it's going to be difficult to get restaurants to serve less food."

And volume is what people want. "I hear it all the time," reports Pouillon. When describing a restaurant, "the first thing people tell me is, 'The portions are enormous. You should see what you get,' not, 'The food was delicious.'

"It's perceived that the more that's on the plate, the better the restaurant," she adds. "It's a quantity notion, not a quality notion."

That's true even in upscale restaurants. "A steak has to be 14 ounces. Otherwise, you don't want to pay for it," says Sirio Maccioni, owner of New York's Le Cirque.

The restaurant patron's desire for more food is stronger now than ever, says industry consultant Locke, because people are feeling "economically flush" these days and want that reflected in their dining experiences. Even in leaner times, he explains, lots of food is what makes the restaurant experience worthwhile for people. "Restaurants don't sell food," he says. "They sell memories. They want you to go home with a good memory. [And] it's a lot easier to make a huge impression on people with a magnificent array of abundance."

So what's a calorie-conscious restaurant diner to do? After all, it's not easy for many people to stop eating if they're full but there's still food left on the plate.

Warshaw recommends that they "practice menu creativity."

"You don't have to order an entree," she says. "You can eat an appetizer" and split an entree and dessert with your dining partner. Or skip the entree or appetizer altogether.

Megan McCrory, lead researcher of the Tufts study, concurs. Sharing works even better than putting some aside for a doggie bag, she says, because it take less willpower. Once you've given some of your food away, she points out, "the amount you eat is automatically controlled." The $2 that some restaurants charge for sharing an entree is well worth it, she says.

If you do plan to bring home a doggie bag, McCrory advises, set a certain amount aside for it even before you begin eating. "Don't wait to see what's left over." Otherwise, it may be too late to keep from overeating.

McCrory also points out that restaurant diners need to make a conscious effort not to overeat because they're usually dining in the company of others, and "people eat more when they're eating with other people," she notes.

Maccioni of Le Cirque, like Warshaw, reminds restaurant patrons that they don't have to have a three-course meal. At his restaurant, he says, a diner could "feel full enough on the first course and a main course. You don't need dessert to feel full." He adds that ordering a low-fat entree doesn't solve by itself the problem of consuming too many calories. "People order broiled fish. While they're waiting, they eat two rolls with butter. So what can we tell you? It's up to the person how much to eat."

Both he and Pouillon point out that, contrary to the beliefs of some diners, they are not at all put off by special requests for such things as sauces on the side, steamed vegetables, plate sharing, doggie bags and the like. "We're not offended" if people want to take half home, says Maccioni. "We're happy about that. It means they like the food."