question:  Obesity Morbid obesity Fat - obese Summary Obesity means having too much body fat. It is not the same as being overweight, which means weighing too much. A person may be overweight from extra muscle or water, as well as from having too much fat. Both terms mean that a person's weight is higher than what is thought to be healthy for his or her height. Causes Taking in more calories than your body burns can lead to obesity. This is because the body stores unused calories as fat. Obesity can be caused by: Eating more food than your body can use Drinking too much alcohol Not getting enough exercise Many obese people who lose large amounts of weight and gain it back think it is their fault. They blame themselves for not having the willpower to keep the weight off. Many people regain more weight than they lost. Today, we know that biology is a big reason why some people cannot keep the weight off. Some people who live in the same place and eat the same foods become obese, while others do not. Our bodies have a complex system to keep our weight at a healthy level. In some people, this system does not work normally. The way we eat when we are children can affect the way we eat as adults. The way we eat over many years becomes a habit. It affects what we eat, when we eat, and how much we eat. We may feel that we are surrounded by things that make it easy to overeat and hard to stay active. Many people feel they do not have time to plan and make healthy meals. More people today work desk jobs compared to more active jobs in the past. People with little free time may have less time to exercise. The term eating disorder means a group of medical conditions that have an unhealthy focus on eating, dieting, losing or gaining weight, and body image. A person may be obese, follow an unhealthy diet, and have an eating disorder all at the same time. Sometimes, medical problems or treatments cause weight gain, including: Underactive thyroid (hypothyroidism) Medicines such as birth control pills, antidepressants, and antipsychotics Other things that can cause weight gain are: Quitting smoking -- Many people who quit smoking gain 4 to 10 pounds (lb) or 2 to 5 kilograms (kg) in the first 6 months after quitting. Stress, anxiety, feeling sad, or not sleeping well. Menopause -- Women may gain 12 to 15 lb (5.5 to 7 kg) during menopause. Pregnancy -- Women may not lose the weight they gained during pregnancy. Exams and Tests The health care provider will perform a physical exam and ask about your medical history, eating habits, and exercise routine. The two most common ways to assess your weight and measure health risks related to your weight are: Body mass index (BMI) Waist circumference (your waist measurement in inches or centimeters) BMI is calculated using height and weight. You and your provider can use your BMI to estimate how much body fat you have. Your waist measurement is another way to estimate how much body fat you have. Extra weight around your middle or stomach area increases your risk for type 2 diabetes, heart disease, and stroke. People with "apple-shaped" bodies (meaning they tend to store fat around their waist and have a slim lower body) also have an increased risk for these diseases. Skin fold measurements may be taken to check your body fat percentage. Blood tests may be done to look for thyroid or hormone problems that could lead to weight gain. Treatment CHANGING YOUR LIFESTYLE An active lifestyle and plenty of exercise, along with healthy eating, is the safest way to lose weight. Even modest weight loss can improve your health. You may need a lot of support from family and friends. Your main goal should be to learn new, healthy ways of eating and make them part of your daily routine. Many people find it hard to change their eating habits and behaviors. You may have practiced some habits for so long that you may not even know they are unhealthy, or you do them without thinking. You need to be motivated to make lifestyle changes. Make the behavior change part of your life over the long term. Know that it takes time to make and keep a change in your lifestyle. Work with your provider and dietitian to set realistic, safe daily calorie counts that help you lose weight while staying healthy. Remember that if you drop weight slowly and steadily, you are more likely to keep it off. Your dietitian can teach you about: Healthy food choices at home and in restaurants Healthy snacks Reading nutrition labels and healthy grocery shopping New ways to prepare food Portion sizes Sweetened drinks Extreme diets (fewer than 1,100 calories per day) are not thought to be safe or to work very well. These types of diets often do not contain enough vitamins and minerals. Most people who lose weight this way return to overeating and become obese again. Learn ways to manage stress other than snacking. Examples may be meditation, yoga, or exercise. If you are depressed or stressed a lot, talk to your provider. MEDICINES AND HERBAL REMEDIES You may see ads for supplements and herbal remedies that claim they will help you lose weight. Some of these claims may not be true. And some of these supplements can have serious side effects. Talk to your provider before using them. You can discuss weight loss medicines with your provider. Many people lose at least 5 lb (2 kg) by taking these drugs, but they may regain the weight when they stop taking the medicine unless they have made lifestyle changes. SURGERY Bariatric (weight-loss) surgery can reduce the risk of certain diseases in people with severe obesity. These risks include: Arthritis Diabetes Heart disease High blood pressure Sleep apnea Some cancers Stroke Surgery may help people who have been very obese for 5 years or more and have not lost weight from other treatments, such as diet, exercise, or medicine. Surgery alone is not the answer for weight loss. It can train you to eat less, but you still have to do much of the work. You must be committed to diet and exercise after surgery. Talk to your provider to learn if surgery is a good option for you. Weight-loss surgeries include: Laparoscopic gastric banding Gastric bypass surgery Sleeve gastrectomy Duodenal switch Support Groups Many people find it easier to follow a diet and exercise program if they join a group of people with similar problems. Possible Complications Obesity is a major health threat. The extra weight creates many risks to your health. Review Date 2/12/2018 Updated by: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. 