What does it mean to have obesity?

Doctors use a calculation called “body mass index,” or “BMI,” to decide whether a person is underweight, at a healthy weight, overweight, or has obesity.

Your BMI will tell you which category you are in based on your weight and height (figure 1):

• If your BMI is between 25 and 29.9, you are overweight.
• If your BMI is 30 or greater, you have obesity.

Obesity is a problem, because it increases the risks of many different health problems. It can also make it hard for you to move, breathe, and do other things that people who are at a healthy weight can do easily.

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 in which you stop breathing for short periods while asleep)
• Asthma
• Cancer

Does having obesity shorten a person’s life?

Yes. Studies show that people with obesity die younger than people who are a healthy weight. They also show that 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” might also be at risk of dying younger. Central obesity means carrying extra weight in the belly area, even if the BMI is normal.

Should I see an expert?

Yes. If you are overweight or have obesity, you can talk to your doctor or nurse. They might have suggestions for healthy ways to lose weight. It can also help to work with a dietitian (food and nutrition expert). A dietitian can help you choose healthy foods and plan meals.

Are there medical treatments that can help me lose weight?

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

What can I do to prevent the problems caused by obesity?

The best thing that 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.
• 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.
• 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 that you can do to improve your health.
• Limit alcohol – For females, drink no more than 1 drink a day. For males, drink no more than 2 drinks a day.

What causes obesity?

The thing that increases a person’s risk the most is having an unhealthy lifestyle. Most people develop obesity because they eat too much, eat unhealthy foods, and move too little. That’s especially true of people who watch too much TV. But there are also other things that seem to increase the risk of obesity that many people do not know about. Here are some things that might affect a person’s chance of developing obesity:

• 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 become have obesity as an adult.
• Sleeping too little – People who do not get enough sleep are more likely to develop obesity than people who sleep enough.
• Taking certain medicines – Long-term use of certain medicines, such as some medicines to treat depression, can cause weight gain. If you are concerned that 1 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 instead.
• Certain hormonal conditions – Some hormonal problems can increase the risk of developing obesity. For example, a condition called “polycystic ovary syndrome” can cause weight gain, along with other symptoms like irregular periods.

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.