Do you sit down in front of your television set every Saturday to watch cartoons? Does the morning slip away as you stare at the set and snack on all kinds of sweet or salty foods?

If you answered yes to these quetions, you're like a lot of other American kids. Studies show that children in the United States watch about 24 hours of television every week. Each year, they spend more time in front of the television than they do in school.

"So what's wrong with that?" you ask.

Well, a recent study conducted by William H. Dietz and Steven L. Gortmaker, two doctors in Massachusetts, suggests that watching that much television can be hazardous to your health. The doctors discovered a connection between television viewing and a condition called obesity.

Obese people are overweight. Some people become obese because of problems with their glands. But in most cases, obesity comes from eating more food than the body can use.

Obesity is serious. Obese people are more likely to develop illnesses like diabetes, high blood pressure and heart disease than people who maintain a normal weight are.

When you eat, your body changes the food into substances it needs to move, grow and stay energetic. We count the energy the body uses in measurements called calories. The things you do use up different amounts of calories. Sitting still watching TV uses only about 80 calories an hour -- while doing something active like riding your bike uses between 250 and 350 calories an hour. If the food you eat contains more calories than you use up, your body produces fat. So if you spend a lot of time eating high-calorie candy while doing a low-calorie activity like watching TV, you start producing fat cells.

Dietz and Gortmaker studied 13,636 kids between the ages of 6 and 17. They found out that kids who watch more than five hours of TV every day were much more likely to be obese than kids who watch only an hour.

You don't have to be a doctor to figure out that kids who watch five hours of TV every day don't have much time left over to exercise.

But that's only part of the problem. A person watching a lot of TV shows sees a lot of commercials. Next time you watch some kids' TV shows, pay attention to what the commercials are about. You'll notice that many of them are about food. When you see the ads, they probably make you wish that you had something to eat -- something like candy, or cake, or salty crackers, all washed down with a soft drink.

"Food is the most heavily advertised product on children's television," . Dietz and Gortmaker says. "Time spent watching TV increases between-meal snacking."

All of that sitting around and snacking can make you fat. But there is something you can do about it. First, turn off the TV. Get on your feet, or your bike, and get some exercise. When you do watch TV, try not to snack as you watch.

Learn to resist the temptation to eat sugar-coated cereal or chocolate- covered nuts every time you see a picture of one on your set. If you're already overweight, you'll probably find yourself losing weight. If you're the right weight for your size, these habits will help you stay that way for life. Tips for Parents

In addition to documenting a connection between TV-watching and obesity, the American Academy of Pediatrics Task force on Children and Television recently outlined several other adverse effects of the hours 2- to 12-year-olds spend in front of the set. These include:

*Exposure to TV violence can promote an inclination toward violence, and apathy when actual violence is seen.

*Learning from TV is passive, not active.

*TV conveys unrealistic messsages regarding drugs, alcohol and tobacco.

*TV promotes ethnic and racial stereotypes, and does little to promote a sympathetic understanding of handicapped people.

*TV conveys an unrealist view of problem solving and conflict resolution.

In spite of these findings, the task force concluded that television can be used creatively and positively -- if you control it, rather than letting it control you and your family. Consider the following guidelines:

*Limit your children's TV viewing. Are they getting enough exercise? Keeping up with schoolwork? Are they reading for fun?

*Practice what you preach. Set a good example with your own TV watching habits.

*Don't use TV as a reward or punishment. By doing so, you'll make TV assume more importance than it should.

*Join your children as they watch TV. Discuss the issues raised on the show, and answer your children's questions.