Healthy nutrition requires a balance of food, vitamins, and minerals (from eating a healthy diet) and physical activity. Overweight and obesity can result if things get out of balance—such as eating too much food, not getting enough physical activity, or having too much of one or more nutrients in the diet.

The United States is facing a very serious public health crisis of overweight and obesity. Today, about 65 percent of adults are overweight or obese. Children are getting heavier as well. The percentage of children and teens that are overweight has more than doubled in the past 30 years. Today, about 17 percent of American children ages 2-19 are overweight.

Extra pounds can add up to health problems, often for life. In adults, overweight and obesity are linked to increased risk of heart disease, type 2 diabetes, high blood pressure, certain cancers, and other chronic conditions.

For children, overweight also increases their health risks. Type 2 diabetes was once rare in children—but now it accounts for 8 to 45 percent of newly diagnosed diabetes cases in American children and teens. And, overweight children are more likely to become overweight or obese as adults.

BMI is a number—a ratio of a person’s weight to height. Health care providers use the BMI to determine a person’s weight status. Health care providers also look at BMI, along with information about additional risk factors, to determine a person’s risk for developing obesity-related diseases.

BMI for Adults
You can use a BMI calculator to figure out an adult’s BMI.

In adults:

• A BMI between 18 and 24 is considered to be a healthy weight.
• A BMI of 25 to 29 is considered overweight.
• A BMI of 30 or above is considered obese.

It is important to focus on reaching and keeping a healthy weight before your BMI reaches 25. See the How can I help prevent overweight and obesity? section below for ideas on how to manage your weight.

BMI for Children and Teens
For children ages two and older, and for teens, BMI uses weight and height, and adds sex and age into the calculation. Instead of using a specific number like adults do, the BMI for children and teens listed as a percent. This percent indicates a child’s BMI in relation to the BMIs of other children the same sex and age.

You can use the Child and Teen BMI Calculator to figure out your child’s BMI.

Children ages two and older are considered:

• At a healthy weight if their BMI falls between the 5th and the 85th percentiles.
• At risk for being overweight if their BMI is in the 85th to 95th percentile.
• Overweight or obese if their BMI is at or higher than the 95th percentile.

There are also some simple steps people can take that can affect their weight and health over the long term. For example, cutting out one soda a day, or taking the stairs instead of the elevator are small changes that can make a big difference in health over time.

Preventing overweight and obesity, especially in children, goes beyond just eating a healthy diet and getting enough physical activity. It may be more helpful to think about adopting a “healthy lifestyle”—and maintaining a healthy weight is just one part of a healthy lifestyle.

A healthy lifestyle could include:

• Eating a healthy diet
• Getting enough physical activity
• Maintaining a healthy weight
• Reducing “screen time”—time spent watching TV, playing video games, or on the computer
• Limiting or eliminating tobacco, drug, and alcohol use
• Reducing stress
• Helping out in your community
• Talking to your health care provider, scheduling and keeping regular well visits, and taking medications correctly

Adopting a healthy lifestyle involves individuals, families, neighborhoods, and communities. This type of lifestyle can make it more likely for people to stay healthy, including controlling their weight and preventing obesity.

A healthy eating plan is one that:

• Emphasizes fruits, vegetables, whole grains, and fat-free or low-fat milk and dairy products.
• Includes lean meats, poultry, fish, beans, eggs, and nuts.
• Is low in saturated fats, trans fats, cholesterol, salt (sodium), and added sugars. Saturated fats, trans fats, and cholesterol tend to raise “bad” (LDL) cholesterol levels in the blood, which in turn increases the risk for heart disease.

For more information on healthy eating, see the diet and nutrition health topic.

Getting enough physical activity is an important way to help prevent or reduce overweight and obesity and related health problems.

• Adults 18 and older need 30 minutes of physical activity on five or more days a week to be healthy.
• Children and teens need 60 minutes of activity a day for their health.

For more information, see our exercise and physical activity health topic.

The NICHD works to help people improve diet and nutrition so they can live a healthier lifestyle. As part of this effort, NICHD participates in health educations programs related to diet and obesity.

• Media-Smart Youth: Eat, Think, and Be Active! is an interactive after-school education program for young people ages 11 to 13. It is designed to help teach them about the complex media world around them, and how it can affect their health—especially in the areas of nutrition and physical activity.

  Media-Smart Youth is not a weight loss program, but rather is a health promotion program. It helps young people become critical, creative thinkers to help them make smart and positive choices about nutrition and physical activity.
  
  

• WE CAN! (Ways to Enhance Children’s Activity and Nutrition) is a national education program to help prevent overweight and obesity among youth ages 8 to 13. WE CAN! offers parents and families tips and fun activities to encourage healthy eating, increase physical activity, and reduce sedentary or screen time. It also offers community groups and health professionals exciting resources to implement programs and fun activities for parents and youth in communities around the country. 

  The program is a collaboration between four NIH Institutes, including the NICHD, the National Heart, Lung, and Blood Institute (NHLBI), the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and the National Cancer Institute (NCI).

• Media-Smart Youth Fact Sheet
• Media-Smart Youth Materials