Your weight has been important since the moment you were born. Maybe you even know what your birth weight was. Most newborns weigh between 6 and 9 pounds, but some may weigh more and some less.

But very quickly, a baby gains weight and everyone is glad about that because it means the child is growing bigger and stronger.

As you get older, your weight is still important. It's something your parents and doctor will probably keep an eye on. When you go for a checkup, the doctor will record your height and weight and compare it with what it was the last time you came in. It’s normal for kids to gain weight because they are still growing. The doctor wants to check that you are not gaining too much or too little. Weighing too much — or too little — can be a problem.

What Does It Mean?

Doctors use the medical terms "overweight" or "obese" to tell if someone has a greater chance of developing weight-related health problems.

When people talk about being overweight, they mean that someone has more body fat than is healthy. Everyone has some body fat, but too much fat can lead to health problems. Overweight kids might find it hard to keep up with friends on the playground. They might be teased or feel bad about themselves.

How Is It Measured?

Someone can be underweight, at a healthy weight, overweight, or obese (very overweight). There is no one perfect weight for a kid to be, but there are healthy weight ranges for kids based on height and gender (whether they're male or female).

Doctors use four categories to describe a person's weight:

1. Underweight: A person weighs less than the healthy range for their age, gender, and height.
2. Healthy weight: A person's weight is in the healthy range for their age, gender, and height.
3. Overweight: A person weighs more than the healthy range for their age, gender, and height.
4. Obese: A person weighs much more than the healthy range for their age, gender, and height.

What Is BMI?

Being overweight is more than a number on the scale. A taller kid naturally could weigh more than a shorter kid and not be overweight. That's why doctors use something called body mass index (BMI) to help decide if a kid is overweight.

BMI estimates how much body fat a person has. It is the result of a calculation that uses a kid's height and weight. The doctor plots that number on a chart. There are different charts for girls or boys.

Because muscle weighs more than fat, a muscular person can have a high BMI, but not too much body fat. Likewise, it's possible for someone to have a low or ideal BMI but still have too much body fat.

You may get a BMI report from school, but the best way to understand BMI is to talk to your doctor.

Why Do People Become Overweight?

Most of the time, people have too much body fat because the body gets more calories (from foods and drinks) than it burns. The body uses some calories to stay alive — keeping the heart beating, lungs breathing, and brain working. You also burn calories through physical activity, such as playing soccer or walking to school.

Calories you don’t use are stored as fat. The more extra calories a person eats, the more fat is stored.

This happens very easily in modern life. People spend more time in front of screens, like TVs, smartphones, and computers, and less time moving around. We drive everywhere instead of walking or riding bikes. Fewer schools have gym classes every day; more kids play video and mobile games than active games like dodgeball.

People lead busier lives so they have less time to cook healthy meals. That may mean more restaurant meals, take-out food, ready-made food, and snacks.

Weight problems can run in families. But don't let that discourage you from making changes that could help you be healthy. Your habits — what foods you eat and how much of them, plus how much you exercise — can make a big difference.

How Can Extra Weight Hurt Your Health?

Being overweight can lead to health problems, like high blood pressure, high cholesterol, and diabetes. It might make it harder to breathe and sleep. It can make it hard to keep up with friends and cause aches or pains. Having a weight problem might make you feel embarrassed, sad, or even angry. When people feel bad, they may eat more because food can be comforting. This isn't a good idea, especially if someone is already overweight.

How Can You Keep From Becoming Overweight?

One of the best ways to stay at a healthy weight is to be active. You can join a sports team. Or if you don't like team sports, try swimming, tennis, martial arts, or just playing in your own backyard. Jumping rope, dancing, and running around will get your heart pumping.

Getting some extra exercise can be as easy as taking the stairs instead of the elevator or walking instead of having your parents drive you. Being active also means watching less TV and playing fewer video and mobile games.

Eating healthy is another part of staying fit. Eat a variety of foods and more fruits and vegetables. Choose water and low-fat milk over soda, juice, sports drinks, and other sugary drinks. When it comes to high-calorie and high-fat foods (like chips, cookies, and ice cream), eat them only once in a while and, when you do, have smaller portions.

What Should You Do?

Talking to a parent is the best first step if you are concerned about your weight. They can help you eat healthy and find ways to be more active. Your mom or dad can make a doctor's appointment for you. The doctor may suggest ways of changing your eating and exercise habits.

In general, kids don't need to diet. But a kid who is very overweight may need some expert help from a dietitian or a doctor who specializes in healthy lifestyles. Together, along with your family, you'll come up with a plan that includes eating nutritious foods and exercising regularly.

Helping Others

If you have a friend or relative who is overweight, remember to be kind. Jokes or teasing can make the person feel bad. Encourage them instead and treat them like all your other friends.