If you're watching what you eat, chances are you pay attention to your fat intake. But what about sugar? Experts contend that Americans eat too much of it--and it's in more of your food than you may realize.

The real problem is sugar added not only to sweets but also to processed foods like frozen dinners and salad dressings. It's this added sugar, not the naturally occurring kind, that can wreak havoc on your waistline and your health.

During digestion, complex sugars--fructose (the sugar found in fruit and honey), lactose (the sugar in milk), and sucrose (table sugar, which also occurs naturally in fruits and vegetables)--break down into simple sugar, or glucose, which provides energy to the body's cells.

Added sugars, on the other hand, may take the form of any number of sweeteners, the most common being high-fructose corn syrup.

Your body makes no distinction between complex and simple or natural and refined sugars--they're all broken down into glucose. That means natural sugars are no better for you than table sugar. What's more important than the type is how much sugar you eat and whether it is taking the place of other nutrients in your diet.

Foods with lots of added sugar may threaten your health for two reasons. First, they tend to be high in calories and can contribute to weight gain. "The number one problem for dieters is calories, and a lot of high-calorie foods [such as cakes, cookies, and candy] are also high in sugar," says marion Nestle, Ph.D., M.P.H., professor and chair of the Department of Nutrition and Food Studies at New York University.

Second, those calories are usually empty--that is, they don't come packaged with health-promoting nutrients like vitamins, minerals, and plant chemicals. And the more you fill up on empty calories, the fewer nutritious foods you're likely to eat.

This doesn't mean sugar is inherently bad for you. Unlike fat, sugar hasn't been linked to chronic diseases. That's why there's no standard recommendation for how much sugar you should eat and why there's no Daily Value for sugar on food labels.

The USDA does, however, suggest limiting added sugars to 6 to 10 percent of your total calories. That's 6 teaspoons a day if you eat about 1,600 calories daily, 12 teaspoons if you consume 2,200 calories, and 18 teaspoons if you eat 2,800 calories.

Again, the problem lies not in how much sugar a particular food contains, but how much of it you consume. Ketchup and teriyaki sauce, for example, list sugar (corn syrup) as the second ingredient--but you eat them by the tablespoon. Cookies, cakes, and ice cream, though, are eaten by the handful, the slice, or the bowlful. Therein lies the problem.

The bottom line? Eat high-sugar foods in moderation, high-fat or not, and choose foods with no added sugar whenever possible.