Health risks of obesity (The Basics)

What is obesity?

Doctors define obesity based on a person's "body mass index," or "BMI." For adults, weight and height are used to calculate BMI.

For people who are White, Hispanic, or Black:

"Overweight" means a BMI between 25 and 29.9.
"Obesity" means a BMI of 30 or greater.

For people who are Asian, the cutoff numbers are a little different:

"Overweight" means a BMI between 23 and 25.
"Obesity" means a BMI of 25 or greater.

In addition to figuring out your BMI, your doctor might also measure around your belly. This is called "waist circumference." Doctors call it "central obesity" when people carry extra weight in the belly area, even if their BMI is normal.

Obesity increases the risks of many different health problems. It can also make it harder for you to move, breathe, and do other activities.

What are the health risks of obesity?

Having obesity increases a person's risk of developing many health problems. Here are just a few examples:

Diabetes
High blood pressure
High cholesterol
Heart disease (including heart attacks)
Stroke Sleep apnea (a disorder that makes you stop breathing for short periods while asleep)
Asthma
Cancer

Does having obesity shorten a person's life?

Yes. Studies show:

People with obesity die younger than people who are a healthy weight.
The risk of death goes up the heavier a person is. The degree of increased risk depends on how long the person has had obesity, and on what other medical problems they have.

People with central obesity (extra weight in the belly area) might also be at risk of dying younger.

Can medical treatments help me lose weight?

Yes. There are medicines and surgery to help with weight loss. These treatments are meant for people who have not been able to lose weight through lifestyle changes such as diet and exercise. Weight loss treatments do not take the place of diet and exercise. People who have the treatments must also change how they eat and how active they are.

How can I prevent the problems caused by obesity?

The best thing you can do is lose weight. But even if weight loss is not possible, you can improve your health and lower your risk if you:

Become more active – Many types of physical activity can help, including walking. You can start with a few minutes a day, and add more as you get stronger and build up your endurance. Anything that gets your body moving is good for you. It is easier to create a habit if you choose activities you enjoy.
Improve your diet – It is healthy to have regular meal times, eat smaller portions, and not skip meals. Limit sweets, and avoid processed foods. Try to eat more vegetables and fruits instead. The best weight loss plans help you have a healthy view of eating.
Quit smoking (if you smoke) – Some people start eating more after they stop smoking, so try to make healthy food choices. Even if it increases your appetite, quitting smoking is still one of the best things you can do to improve your health.
Limit alcohol – For females of any age, limit alcohol to no more than 1 drink a day. For males 64 and younger, limit alcohol to no more than 2 drinks a day. For males 65 and older, limit alcohol to no more than 1 drink a day.

Keeping a diary might help you reach your daily goals. You can use a paper diary or app to help you record:

What you eat and drink
Your physical activity Your weight

What causes obesity?

Your genes affect your risk of obesity. But lifestyle also has a big impact. You can develop obesity if you eat too much, eat unhealthy foods, move too little, and watch a lot of TV.

There are other things that seem to increase the risk of obesity you might not know about. Here are some:

Mother's habits during and after pregnancy – People who eat a lot of calories, have diabetes, or smoke during pregnancy have a higher chance of having babies who have obesity as adults. Also, babies who drink formula might be more likely than breastfed babies to develop obesity later in life.
Habits and weight gain during childhood – Children or teens who are overweight or have obesity are more likely to have obesity as an adult.
Sleeping too little – People who do not get enough sleep are more likely to develop obesity.
Taking certain medicines – Long-term use of certain medicines can cause weight gain. If you are concerned one of your medicines might be making you gain weight, talk to your doctor or nurse. They might be able to switch you to a different medicine.
Certain hormonal conditions – Some hormonal problems can increase the risk of developing obesity. For example, hypothyroidism can cause weight gain, along with other symptoms.

What if I want to get pregnant?

If you are overweight or have obesity, it might be harder to get pregnant. For males, obesity can also cause sex problems, like having trouble getting or keeping an erection. This is more likely if you also have high blood pressure or diabetes.

What if my child has obesity?

In children, obesity has many of the same risks as it does in adults. For example, it can increase the risk of diabetes, high blood pressure, asthma, and sleep apnea. It can also cause added problems related to childhood. For example, obesity can make children grow faster than normal and cause girls to go through puberty earlier than usual.

When should I call the doctor?

Call your doctor or nurse if you want to try to lose weight. They can help you do it in a healthy way. It can also help to work with a dietitian (food and nutrition expert). They can help you choose healthy foods and plan meals.