Obesity is a major health problem in the United States and worldwide. It affects nearly 2 out of 5 adults in the U.S.

Obesity is having a body weight that is above a normal weight for a specific height. Obesity is measured by using BMI (body mass index). BMI is a formula. It uses a person's weight divided by their height. BMI may be used to screen for weight problems. BMI does not diagnose health problems or a person's body fat. But a high BMI number can mean high body fat. A BMI between 18.5 and 25 is normal. A BMI between 25 and 30 falls within the overweight range. A BMI of 30 or higher is within the obese range. A BMI of 40 or more is extreme or severe obesity.

Carrying too much weight can increase your risk for many serious health issues. These include problems with your heart, lungs, blood vessels, brain, and joints. Some of the problems that can happen include:

• Heart and circulation problems. These include heart disease and high blood pressure. They also include heart rhythm problems (atrial fibrillation) and stroke.
• Type 2 diabetes.
• Certain cancers. These include colon and breast cancer.
• Sleep apnea and other breathing problems.
• Back or joint problems. These include osteoarthritis and gout.
• Digestive tract problems. These include gallstones and GERD (gastroesophageal reflux disease).
• Depression (with severe obesity).

Carrying too much weight can also affect your quality of life. And it can keep you from doing things you want or need to do.

You can lower your risk for health problems from obesity by managing your weight. If you are overweight or obese, the first step is to lose weight. Studies show that losing as little as 5% of your body weight is good for your health.

An important part of losing weight is building healthy habits and behaviors. Here are some tips:

• Control how much you eat. Food is your body's way to get energy (calories). You'll gain weight if you take in more calories than your body uses. Know your eating habits. And watch your portion size.
• Make healthy eating choices. Choose foods with many nutrients. They can give your body the energy it needs without adding extra pounds. Also limit foods with added sugar and fats.
• Be more active. Exercise burns calories. This can help you manage your weight. Try to move more each day. You can do this by adding aerobic activity, like walking daily. You can also do strength training.
• Talk with your health care provider. Ask about working with a dietitian, a health coach, an exercise physiologist, or a mental health provider. They can give you a lot of support.

If you have trouble losing weight, talk to your provider. Your provider may suggest medicines to help. Weight loss (bariatric) surgery may also be a choice for adults who have:

• A BMI of 40 or more, or who are more than 100 pounds overweight.
• A BMI of 35 to less than 40 and a serious health problem. These include type 2 diabetes, high blood pressure, or sleep apnea.
• Not been able to stay at a healthy weight for a while. This is in spite of efforts to lose weight through diet, exercise, or medicines.