(Cox News Service) -- A strange thing happened when low-fat foods became all the rage about 10 years ago.

People gained weight.

"They started eating all the cookies they wanted," said Lisa Arose, trained in nutritional science at Columbia University before becoming a research associate for Wright State University's Center for Urban and Public Affairs (CUPA). "Obesity rates went up instead of down. People were eating more calories."

Low in fat doesn't mean low in calories. In fact, low-fat foods tend to have more sugar to make up for the taste that's removed with the fat.

"The laws of physics still apply," said Richard Cohen, a dietitian who directs the HMR Weight Management Program at Greene Memorial Hospital. "When people's total caloric intake is up and people's exercise is down, the body will store the excess calories as more weight."

The news that calories convert to body weight hardly surprises anyone, of course. But people have a lot of nutritional misconceptions that lead them to consume more calories than they intended. For example:

Salads aren't necessarily low in calories. The greens and other vegetables are, but then people add bacon bits, cheese, croutons, tuna salad and dressing. "We can make anything unhealthy," said Jane Dockery, CUPA's associate director.

"Fat-free salad dressings are basically syrup," Cohen said. "They're just loaded with sugar."

The same principle applies to the mayonnaise and type of bread on a turkey sandwich. Don't be fooled by the "market fresh" in Arby's sandwiches, Arose warned. The Market Fresh Roast Turkey and Swiss sandwich, for instance, has 760 calories, 33 grams of fat and 75 grams of carbohydrates.

Coffee is low-cal, but cream and whipped cream are not. "You go to those coffee shops, and some of the drinks might as well be a cup of Haagen-Dazs ice cream," Arose said.

Bagels can sneak up the same way. Cinnamon crunch just about doubles the calories in a fairly plain bagel, she said, "and that's without the cream cheese." A plain bagel, for instance, has about 150 calories; a bakery bagel with cream cheese might have as many as 500 calories.

Just because juice and dairy products are healthy doesn't mean they'll help you lose weight. "One glass of juice is healthy," said Pamela Reichel, health educator at Good Samaritan Hospital. "But a lot of what people drink is just sugar and calories, and not even that good for them." That's because a lot of the "juice" people drink has far less than 100 percent juice.

Milk has "a lot of fat and a lot of calories," she said. "But we see people drinking six or eight glasses of whole milk a day because they've heard milk is good for them."

Even the required nutritional labels have loopholes. One is "serving" sizes. The information can cut the actual calories, fats and carbohydrates in half just by saying the package contains two servings. One snack package of Grandma's Homestyle Chocolate Chip Cookies, for instance, actually constitutes two servings. If you eat both cookies in the package, you consume 400 calories, 18 grams of fat and 56 grams of carbohydrates.

Cereals aren't necessarily high in fiber. "Most people think Special K is very good for you," Arose said, "but it's very high in carbohydrates, very low in fiber, and you also probably eat more than one serving size." A cup of Special K cereal has just 1 gram of fiber - no more than in many kids' cereals like Frosted Flakes or Froot Loops.

Pretzels have the same problem, she said, despite being low in fat and calories. "That's why a lot of people say pretzels don't fill them up."

Carbohydrates come in two types, simple and complex. Simple carbs, sugar among them, go straight to the bloodstream. "A high-fiber complex carb like beans, lentils, whole grains, oatmeal . . . they're not going to spike your blood sugar up and back down, give you mood swings and make you hungry 15 minutes later."

The famous food guide pyramid, even with periodic revisions by the U.S. Department of Agriculture, "was built on less-than-solid scientific ground and has never been updated," said Dr. Walter C. Willett, nutrition chairman at the Harvard School of Public Health. Willett created his own pyramid in the book "Eat, Drink, and Be Healthy." It takes white bread, rice and pasta from the USDA's foundation layer and moves them to the top, "eat sparingly" triangle.

It also moves olive, canola, soy and sunflower oils and other healthy fats from the USDA's upper triangle to his own eat-plenty foundation level, along with whole grains. Few dietitians find these moves at all controversial.

"The problem is, there's no place to learn this stuff," Arose said. "They don't teach it in health class at school. But people learn about the food guide pyramid, and it doesn't even differentiate between white bread and black beans."

Copyright 2002 Cox News Service. All rights reserved.