JUNK FOOD,.

it's the 21st century and "junk food" has gone global. For better or for worse (mostly worse), junk food is now available all over the world. We see it most everywhere we go -- in grocery and convenience stores, fast-food restaurants, on television -- usually looking very appealing. But just what are the facts about junk food?

"Junk food" generally refers to foods that contribute lots of calories but little nutritional value. Of course, what's considered "junk food" depends on whom you ask. Some might say pizza is junk food, for example. But I personally don't think so, since it contributes real food with nutrients, like cheese and tomato sauce. Add whole-wheat or part whole-wheat crust, plus veggies as a topping, and I'd say pizza completely exits the junk food category.

One problem with junk foods is that they're low in satiation value -- that is, people don't tend to feel as full when they eat them -- which can lead to overeating. Another problem is that junk food tends to replace other, more nutritious foods. When people drink lots of soda, for example, they are usually not getting plenty of low-fat dairy or other healthful beverages like green tea or orange juice. When they're snacking on chips and cookies, they're usually not loading up on fruits and vegetables.

Most "junk food" falls into the categories of either "snack food" or "fast food." And then there are things like breakfast cereals. They seem innocent enough, but some of them could definitely be considered "junk food," as they mostly contain sugar or high-fructose corn syrup and white flour or milled corn.

Calories From Snack Foods

Popular snack foods are usually commercially prepared and packaged, like chips, cheese puffs, candy bars, snack cakes, and cookies.

The contribution of snack food to the calories we eat should not be underestimated. Between 1977 and 1996, the contribution of snack calories to total calories for American children between 2 and 5 years old increased by 30%, according to an article published in the Chilean medical journal, Revista Medica de Chile.

Fast Food and Overeating

Of course, junk food is also readily available at restaurant chains across the country in the form of French fries, chicken nuggets, shakes, soda, etc. Not only are most fast foods not terribly healthy, one study indicates that there may be something about fast food that actually encourages gorging.

In the study, from the Children's Hospital in Boston, teens age 13-17 were given three types of fast-food meals (all including chicken nuggets, French fries, and cola). In one meal, the teens were served a lot of food at once. In another, a lot of food was served at the same time, but in smaller portions. And in the third test meal, a lot of food was served, but in smaller portions over 15-minute intervals.

The researchers found that it didn't seem to matter how much food was served -- the teens still took in about half of their daily calorie needs in that one meal. The researchers suggested that certain factors inherent to fast food might promote overeating:

• It's low in fiber.
• It's high in palatability (that is, it tastes good).
• It offers a high number of calories in a small volume.
• It's high in fat.
• It's high in sugar in liquid form.