What is obesity?

Many people are concerned about their weight. Society emphasizes being thin, and heavier people often are very aware of their weight and how they are seen by others. We hear in the news that more and more people are becoming overweight and obese—but what does this mean?

Obesity means having too much body fat (adipose tissue). Obesity generally is determined by calculating your body mass index (BMI), which measures weight for height and is stated in numbers. BMI is not about how you look but rather an indication of the effect your weight has on your health. If you have too much weight for your height, you are at risk for developing health problems, such as type 2 diabetes.

A BMI of 30 or higher is considered obese in adults—you are at a higher risk for certain health problems than those with a lower BMI. As BMI increases, your risk of health problems increases.

Obesity is considered a long-term, complex disease. Many factors are involved in determining why some people are heavier than others and how much risk they have for developing other health conditions. Some of these factors are genetic (you have inherited them) and others have to do with your culture, environment, and behavior.

If your BMI is between 25 and 30, you are considered overweight (and also at increased risk for certain diseases). For information on maintaining a healthy weight, see the topic Healthy Weight.

What causes obesity?

You gain weight when you consume more calories from food than your body uses through its normal functions (basal metabolic rate [BMR]) and physical activity. The unused calories are stored as fat. You become obese if you consistently consume excess calories over a long period of time. For example, eating an extra 100 calories per day (less than half a turkey sandwich) can lead to a gain of about 10 lb (4.5 kg) in a year. Gaining 10 pounds a year eventually will result in a BMI of 30 or higher.

However, calories alone do not explain weight gain and why some people gain (or lose) weight more easily than others. Other factors that play a major role in weight gain and obesity include:

Genetics. If either of your parents were obese, you are more likely to be obese.
Eating behavior. A diet high in fat and low in fruits and vegetables may lead to weight gain and obesity.
Your activity level. Activity uses calories, which helps balance the calories you get through food. If you are inactive, it may be easier to gain weight.
Your environment. Being part of a culture that has readily available, inexpensive food and that emphasizes high-fat foods and large portions can lead to more calories and more weight.
What health problems does obesity put me at risk for?

According to the U.S. National Institutes of Health, all people age 18 or older who have a BMI of 25 or higher are considered at risk for disease and early death because of being overweight or obese. 1

If you are obese, you are more likely to develop type 2 diabetes, high blood pressure, coronary artery disease (CAD), stroke, and sleep apnea, among other conditions. If you lose weight, your risk for these conditions is reduced.

Often overlooked are the psychological and cultural problems associated with being obese. Stereotypes of obese people—such as that they are lazy—and the emphasis our society places on thinness may result in low self-esteem, a poor body image, depression, and eating disorders. Stereotypes also may make it more difficult for an obese person to find a job or to progress in one.

How is obesity diagnosed?

Your health professional will take your medical and family history, do a physical examination, and use your BMI to determine whether you are obese.

Healthy weight (BMI) chart for adults
Healthy weight (BMI) chart for adults (metric)
Your health professional may measure your waist or determine your waist-to-hip ratio (WHR) to determine how excess fat is distributed on your body. The location of body fat helps determine your risk for other health problems.

If your weight or family history suggests you have an increased risk for developing related health problems, your health professional may want to do more tests. The most common tests are for high blood pressure and blood tests to check for type 2 diabetes, high cholesterol or triglycerides, and thyroid problems.

How is obesity treated?

Because obesity is a chronic disease, it requires long-term management. Treatment focuses on losing weight to improve or eliminate related health problems or the risk for health problems, not to attain an ideal weight. Treatment consists of modifying your eating behaviors, physical activity, and monitoring your behavior, such as tracking what triggers you to eat. Medication and surgery may be used if this treatment is not effective.

Treatment also covers the psychological and social components of obesity. Stress management and counseling may be helpful. Getting family support and creating community contacts help you deal with the stereotypes and other social issues that are associated with obesity.

Health tools help you make wise health decisions or take action to improve your health.

Decision Points focus on key medical care decisions that are important to many health problems.
Should I have surgery to treat obesity?
Should I use prescription medications to treat obesity?

Cause

You gain weight when you consume more calories from food than your body uses through its normal functions (basal metabolic rate [BMR]) and physical activity. The unused calories are stored as fat. You become obese if you consistently consume excess calories over a long period of time. For example, eating an extra 100 calories per day (less than half a turkey sandwich) can lead to a gain of about 10 lb (4.5 kg) in a year. Gaining 10 pounds a year eventually will result in a BMI of 30 or more and obesity.

However, calories alone do not explain weight gain and why some people gain (or lose) weight more easily than others. Other factors play a major role in weight gain and obesity.

Genetics

Body weight is somewhat determined by genetics. If one of your parents is obese, you are 3 times as likely to be obese as someone with parents of healthy weight. 2

The ways in which your body responds to food intake and activity patterns also reflect the influence of genetic factors on your weight. For example, genes influence how calories are used (energy metabolism). Some people use calories efficiently—they use fewer calories to fuel the body, which can result in "leftover" calories being stored as fat. Other people use calories less efficiently—they need more calories to fuel the body, so there are fewer calories left over to store as fat.

Genetics only determines the tendency to become obese, and factors such as your environment, activity level, and eating behavior determine whether you actually become obese. 3

Eating behavior

How much you eat affects your weight. The more you eat, the more likely it is you will gain weight. What you eat also affects your weight. A high-fat diet may provide too many calories even if you eat reasonable portions. When and how you eat is also important. Not eating regular meals, eating quickly, and skipping meals may also contribute to weight gain and obesity.

Activity level

Physical activity uses calories. This includes not only exercise—such as jogging, swimming, or walking—but also activities such as gardening and washing the car. The fewer calories you use through physical activity, the more likely you are to gain weight.

Environmental influences

Your environment plays a role in whether obesity develops. These influences include:

Your family's behavior. If your family or friends eat a lot of high-fat or snack foods, eat at irregular times, and eat quickly, you probably will, too. This can influence calorie intake and weight.
Availability. Food in North America is generally readily available and inexpensive.
Culture. Advertising and marketing play a role in what we eat. The emphasis on high-calorie foods and large portions can lead to more calories.
Other factors that influence eating behavior include your daily routine, your knowledge of nutrition, and your stress level.

Other possible factors in weight gain include medical conditions, such as Cushing's syndrome or depression, and the use of medications, such as antidepressants and corticosteroids.

Symptoms

To be considered obese, an adult must have a body mass index (BMI) of 30 or higher.

You may experience symptoms of conditions that are associated with obesity. These include snoring (sleep apnea), heartburn (gastroesophageal reflux disease, or GERD), and painful joints (arthritis).

Obesity may also have psychological effects. The pressure to be thin and stereotypes of people who are obese may lead to a negative self-perception and body image, self-loathing, and depression.

To fit the medical definition of obesity, your extra weight must come from having too much body fat. Not everyone with a BMI over 30 is obese. For example, athletes may have a BMI over 30, but because their weight is due to muscle, not fat, they are not considered obese.

What Happens

Obesity often begins in childhood; studies report that 30% of adult obesity begins at this time. 4 Without treatment, most people who are obese will either continue to slowly gain weight or remain at their current weight. With treatment, most people who are obese will be able to lose some weight or stop gaining weight. Most of those who lose weight gain some back.

According to the U.S. National Institutes of Health, all people age 18 years or older who have a body mass index (BMI) of 25 or higher are considered at risk for disease and early death because of being overweight or obese. 1 Health risks increase as the severity of your obesity increases.

How obesity affects your heath depends on a number of factors, including your age, gender, fat distribution, and how physically active you are. For example, if you are an obese older woman who gets regular physical activity, you may be at less risk for other health problems than a younger obese man who is not physically active.

Medical conditions that may develop

If you are obese, you are more likely to develop type 2 diabetes, high blood pressure, coronary artery disease (CAD), stroke, and sleep apnea, among other conditions. If you lose weight, your risk for these conditions is reduced.

The location of body fat is also important. If fat accumulates mostly around the abdomen (central obesity, sometimes called apple-shaped), you are at greater risk for type 2 diabetes, high blood pressure, high cholesterol, and CAD than people who are lean or people with fat around the hips (peripheral obesity, sometimes called pear-shaped).

See a chart on BMI, waist size, and risk for disease.
See more information on health problems related to obesity.
Years of life lost

People who are obese do not live as long as those who are not obese, and the earlier a person becomes obese, the more years of life are lost. One study reports that, compared to 40-year-old nonsmokers of healthy weight (a BMI of 18.5–24.9): 5

Obese 40-year-old nonsmoking women lost about 7 years of life.
Obese 40-year-old nonsmoking men lost about 5.5 years of life.
Obese 40-year-old smoking men and women lost about 13 years of life.
People who are obese are at greater risk of death from cancer. In the United States, compared to people of a healthy weight, people who are: 6

Obese (BMI of 30–34.9) have a 9% (men) or 23% (women) increased risk of death from cancer.
Very obese (BMI of 35–39.9) have a 20% (men) or 32% (women) increased risk of death from cancer.
Extremely obese (BMI of 40 or higher) have a 52% (men) or 62% (women) increased risk of death from cancer.
See a table of how obesity increases the risk of death from cancer for men and for women.

Emotional and social impacts

Being obese may lead to emotional problems. Stereotypes of obese people—such that they are lazy—and the emphasis our society places on thinness may result in low self-esteem, a poor body image, depression, and eating disorders. Stereotypes may also make it more difficult for an obese person to find a job or to progress in one. However, if you have strong support from family and friends, you may not be affected by the emotional and social negatives toward obesity.

What Increases Your Risk

Risk factors you cannot control

Body weight is somewhat determined by genetics. If one of your parents is obese, you are 3 times as likely to be obese as someone with parents of healthy weight. 2 The ways in which your body responds to food intake and activity patterns also reflect the influence of genetic factors on your weight. However, it is important to remember that genetics only determines the tendency to become obese, and that factors such as your environment, your activity level, and your eating behavior determine whether you actually become obese. 3

Risk factors you can control

The basic cause of obesity is an energy imbalance over a long period of time. You gain weight when you consistently take in more energy (measured in calories) from food than you use. The excess energy is stored as fat. You can control your energy balance through your diet and physical activity.

Overeating provides too many calories.
A high-fat diet may provide too many calories even if you eat reasonable portions.
Little physical activity means fewer calories are used.
Risk factors you may be able to treat

Some people with emotional or psychological problems may be at increased risk for gaining too much weight. These problems may include:

Low self-esteem. Dissatisfaction with your body lowers your self-esteem, which may lead to eating as a way to comfort yourself. Repeated failure at dieting also can affect your self-esteem and make it even more difficult to lose weight.
Emotional concerns. Emotional stress, such as worry or anxiety, or emotional illnesses, such as depression, can lead to overeating. Some people eat to calm themselves, avoid dealing with unpleasant tasks or situations, or dampen negative emotions.
Eating disorders. Some people may control their eating a large part of the time but have periods when they cannot stop from eating large amounts of food (binge eating).
Trauma. Distressing events can contribute to overeating, such as childhood sexual or nonsexual abuse, loss of a parent during childhood, or marital or family problems.
Alcohol. Some forms of alcohol (beer and mixed drinks) are very high in calories. Weight gain from alcohol is associated with greater abdominal fat.
Medications or other medical conditions. Other conditions, such as hypothyroidism and Cushing's syndrome, and medications, such as antidepressants and corticosteroids, may cause weight gain.
Risk factors for developing associated health problems

The following factors increase your risk for developing health problems associated with obesity. 2

Your ethnicity plays a role. For example, Southeast Asians have a higher risk of type 2 diabetes and cardiovascular disease at the same body mass index (BMI) than whites do.
A waist circumference greater than 40 in. (101.6 cm) (if you are a male) and 35 in. (88.9 cm) (if you are a female) puts you at increased risk for type 2 diabetes, high blood pressure, high cholesterol, and coronary artery disease (CAD). A large waist circumference is a sign of fat that accumulates mostly around the abdomen (also called central obesity or apple-shaped). See a chart on BMI, waist size, and risk for disease.
Weighing 11 lb (5 kg) or more than you did when you were 18 to 20 years of age puts you at increased risk for type 2 diabetes, high blood pressure, gallstones, and CAD. The more weight you have gained since this age, the greater your risk.
Being in poor aerobic shape increases your risk of type 2 diabetes and cardiovascular disease.

When To Call a Doctor

Call 911 or other emergency services immediately if you are obese and experience:

Chest pain.
Signs of a stroke.
If you are obese and want to try losing weight or controlling your weight, make an appointment with your health professional to discuss:

Why you are obese. Many factors are involved, and identifying them will help you lose weight.
Any medication, especially antidepressants or antipsychotics, you may be using. Medications may contribute to weight gain.
Safe ways to lose or control weight.
How much weight you should try to lose to benefit your health. Often a loss of only a few pounds or kilograms can greatly reduce your risk for developing certain diseases.
Call your health professional if you have gained 10 lb (4.5 kg) or more in a few months. Your health professional can determine the reason for your rapid weight gain. Rapid weight gain may also indicate another problem.

Watchful Waiting

Watchful waiting is a period of time during which you and your health professional observe your symptoms or condition without using medical treatment. Watchful waiting is not an option if you:

Are obese (have a body mass index [BMI] of 30 or more).
Are overweight (have a BMI of 25 to 29.9) and have two or more health problems that obesity may make worse, such as coronary artery disease or type 2 diabetes.
Have a waist circumference of 40 in. (101.6 cm) (if you are a male) or 35 in. (88.9 cm) (if you are a female), and two or more health problems that obesity may make worse.
Have rapid weight gain [gain of 10 lb (4.5 kg) or more in one month].
All of these indicate a high risk of health problems, and you should discuss your situation with a health professional. This is even more important if a family member has high blood pressure, high cholesterol or triglycerides (fats), or diabetes.

If your BMI is 25 to 29.9 and you have no health problems that obesity may make worse, watchful waiting may be appropriate. Talk to your health professional about healthy eating habits. For more information, see the topic Healthy Eating.

Who To See

Your family health professional can usually diagnose and treat obesity. However, some health professionals are better prepared to treat obesity than others. Talk with your health professional about his or her interest and training in treating this disease. He or she may refer you to other health professionals, such as:

A registered dietitian, to help you determine how many calories you need and how best to get them.
An exercise specialist or personal trainer, to help you develop a safe and effective exercise program.
A counselor or psychiatrist if you have an emotional problem such as depression or anxiety, have experienced sexual or physical abuse, have family problems, or abuse drugs or alcohol.
A surgeon, if you and your health professional think that obesity (bariatric) surgery is an option.
To prepare for your appointment, see the topic Making the Most of Your Appointment.

Obesity is diagnosed through a history and physical examination. Laboratory tests may be done to check for associated problems.

During a history and physical examination, your health professional will determine:

Your body mass index (BMI) to see whether you are obese.
How excess fat is distributed on your body, by calculating your waist measurement. Knowing this helps determine your risk for developing type 2 diabetes, high blood pressure, high cholesterol, and coronary artery disease (CAD).
Whether your weight or family history suggests you have an increased risk for developing related health problems.
If your health professional feels you are at risk for related health problems, he or she may check for high blood pressure and run blood tests to check for type 2 diabetes, thyroid problems, and high cholesterol or triglyceride levels.

If you are obese, your health professional may ask you questions to determine your motivation to lose weight, such as why you want to lose weight and what happened in any previous attempts to lose weight.

Early Detection

While there is no screening program for obesity, checking your height and weight is a standard part of a visit to your health professional. Doing so allows you to determine your BMI and whether you are obese.

Obesity requires long-term management. The goal of treatment is weight loss to improve or eliminate related health problems, or the risk for them, not to attain an ideal weight.

Treatment consists of modifying your eating behaviors, physical activity, and monitoring your behavior, such as understanding what may trigger you to eat. If this treatment does not help you lose weight, medications may be considered. In extreme cases surgical procedures can reduce the size of the stomach and limit how may calories the intestines absorb.

Treatment also covers the psychological and social components of obesity. Stress management and counseling may be helpful. Family support and creating community contacts help you deal with the stereotypes and other social issues that are associated with obesity.

Restricting your calories and increasing activity are the major components of treatment for obesity. When following this treatment plan, keep in mind the following:

Although a very low-calorie diet results in quick weight loss, the weight is often gained back. Over the long term, a low-calorie diet and a very low-calorie diet have similar results. 2, 7
Research indicates that the most important factor in dieting is not the type of food you eat, but how many calories you restrict. For example, restricting only carbohydrates or fat will not result in any more weight loss than an overall low-calorie diet. 2, 8 In a low-carbohydrate diet, such as the Atkins diet, calorie restriction, the length of the diet, and your initial weight may be more important factors than carbohydrate restriction. 9 See more information on popular diets for obesity, such as the Zone, Atkins, and Sugar Busters diets.
Research indicates that physical activity is less helpful for initial weight loss than for maintaining weight loss. 2
The U.S. National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH) recommends treatment for anyone who wishes to lose weight and: 1

Is obese (has a body mass index [BMI] of 30 or higher).
Is overweight (has a BMI of 25 to 29.9) and has two or more health problems that obesity may make worse, such as coronary artery disease or type 2 diabetes.
Has a waist circumference of 40 in. (101.6 cm) (in men) or 35 in. (88.9 cm) (in women), and two or more health problems that obesity may make worse.
For these people, the NHLBI recommends: 1

Losing 10% of their current weight at a rate of 1 lb (0.45 kg) to 2 lb (0.9 kg) a week for six months.
After 6 months, reevaluating to determine whether they need to lose more weight. If they have met their weight-loss goals, their health professionals may suggest weight maintenance.
You may begin to see an improvement in health problems related to obesity, or reduced risk for these problems, after losing 5% to 10% of your weight. 2

Health professionals recommend treating any bone or joint (orthopedic) problems that limit your ability to exercise before starting a weight-loss program; however, exercise can improve some joint problems. Discuss what exercise program you might need with your health professional.

Initial treatment

Initial treatment of obesity consists of modifying your eating behaviors, physical activity, monitoring your behavior (such as understanding what may trigger you to eat), and if necessary, getting social, emotional, and psychological help.

Before beginning treatment, it is important to decide whether you want to lose weight. If you are not motivated to do so, it will be more difficult to make the lifestyle changes necessary to lose weight. Your health professional may ask you questions to determine your motivation to lose weight, such as why you want to lose weight and what happened in any previous attempts.

If you are not ready to lose weight, your health professional will help you maintain your current weight and may want to explore barriers to changing your eating behavior.

If you are ready to lose weight:

Have reasonable goals and expectations Many obese people expect to lose much more weight than is realistic. When they do not achieve their goals, it can have a negative effect on self-perception. See questions to consider when setting weight management goals to help you define clear, healthy goals.

Get family and friends involved Losing weight is not always easy and the support of those around you is important. Talk to them about why you are changing your diet and activity levels and how important losing weight is to you. Ask them to help by participating in your activities and having meals with you, even if they may be eating something different.

Change your eating behavior Consuming fewer calories is the best way to lose weight. For most adults, a low-calorie diet of 1,200 to 1,500 calories per day for women and 1,500 to 1,800 calories per day for men is recommended for weight loss. In some cases, a very low-calorie diet may be considered, but generally is not recommended, and should only be conducted under close medical supervision. A registered dietitian can help you determine how to change your diet to restrict calories but still receive necessary nutrients. You can help yourself consume fewer calories by:

Planning your meals, which helps you eat regular meals and a balanced, nutritious diet. It can also save you money shopping.
Working to maintain your new diet, such as by not skipping meals and eating small serving sizes.
Cutting fat from your diet.
Using lean meats and meat alternatives.
Increase your activity level Physical activity increases the number of calories you use. Talk to your health professional about starting a fitness program and how to structure it. If you have not exercised much in the past, your health professional might first recommend a small amount of daily aerobic activity. The long-term goal is at least 30 minutes of moderate aerobic activity per day, every day. See physical activity for weight loss. For more information on exercise and fitness, see the topic Fitness.

Watch yourself Stress, your environment, and how you react to changes in eating behavior and activity levels can lead to weight gain or “falling off” your diet. Being aware of these factors can help you lose weight.

Self-monitoring identifies obstacles to losing weight, triggers that may lead you to overeat, and irrational thoughts about eating. It also can help you track your progress in modifying your eating behaviors and activity levels.
Understanding the connection between stress and eating can help you determine whether you eat to calm yourself. If so, take action to reduce your stress level.
Managing your environment helps you remove food temptations and, when you do eat, to consume fewer calories.
Understanding and preventing relapse helps you overcome and avoid falling off your diet or reverting back to old eating habits.
Be aware of emotional aspects of weight loss Individual or group counseling is an important part of treatment if you have psychological and social problems that lead you to eat too much or get too little activity. In addition, dieting or exercising with a support system of friends may lead to greater motivation and self-acceptance. Treatment for any emotional illnesses, such as depression or anxiety disorder, or for an alcohol or drug problem or sexual or physical abuse can help you be more successful at weight loss.

Ongoing treatment

Ongoing treatment for obesity continues the actions you have started.

Revise your weight-loss goals if necessary, and keep your family and friends involved.
Consuming fewer calories is the best way to lose weight. For most adults, a low-calorie diet of 1,200 to 1,500 calories per day for women and 1,500 to 1,800 calories per day for men is recommended for weight loss. In some cases, a very low-calorie diet may be considered, but it generally is not recommended. Find ways to maintain your diet, such as not skipping meals, planning your meals, cutting fat from your diet, and using lean meats and meat alternatives.
Gradually increase your activity level. Add 5 or 10 minutes or a few more days a week to your aerobic exercise program. The long-term goal is moderate aerobic activity, at least 30 minutes a day, every day. See physical activity for weight loss.
Continue to monitor your progress, identify new triggers that may lead you to overeat, and identify and change irrational thoughts about eating. Do not be discouraged if you “fall off” your diet or activity schedule. Accept this for what it is—a temporary setback—and continue with your changes. If you feel you have "failed your diet," talk to a family member or friend about it.
Understand the connection between stress and eating. If you eat to calm yourself, find ways to reduce your stress level.
Manage your environment to help you remove food temptations and consume fewer calories.
Understand and prevent relapse to help you overcome and avoid falling off your diet or reverting back to old eating habits.
If you are working with a counselor or support group, continue to do so.
You may have lost weight but gained it back. Don't be discouraged; it is not uncommon to try several times before weight comes off and stays off. Talk to your health professional about starting again. It may be helpful to work with others trying to lose weight in a structured program.

When treatment has lasted for 6 months, talk to your health professional. You may need to adjust your diet or physical activity. If you have not lost any weight, or continue to gain weight, discuss using medications with your health professional.

Weight-loss medications, either prescription or nonprescription, generally are used along with a weight-loss diet and exercise. Use of medication without lifestyle changes is unlikely to have long-term success. Medications for weight loss include sibutramine, orlistat, and phentermine.

Should I treat obesity with medication?

If you have reached your 6-month goal, talk to your health professional about maintaining your new weight. Develop healthy eating habits so that you do not regain the weight you have lost.

A plan for healthy eating provides a road map for developing and maintaining healthy eating habits. It helps you set goals, track your progress, and reward yourself.
Meal planning helps you eat regular meals, which provide a balanced, nutritious diet. It can also save you money shopping.
Make healthy fast food, restaurant, and convenience food choices to maintain your diet when eating out.
Physical activity is important in maintaining weight loss. Continue with your current program or increase your activity level. The long-term goal is moderate activity, at least 30 minutes a day, every day. See physical activity for weight loss. For more information, see the topic Fitness.
For more on developing and maintaining healthy eating habits, see the topic Healthy Eating.

Treatment if the condition gets worse

You may have lost weight but gained it back. Don't be discouraged; it is not uncommon to try several times before weight comes off and stays off. Talk to your health professional about starting again. It may be helpful to work with others trying to lose weight in a structured program.

If you do not lose weight, continue to gain weight, have lost weight several times only to regain it, or if your health professional is concerned about a related health problem, you might need to try medications or surgery.

Weight-loss medications, either prescription or nonprescription, generally are used along with a weight-loss diet and exercise. Use of medication without lifestyle changes is unlikely to have long-term success. Medications for weight loss include sibutramine, orlistat, and phentermine.

Should I treat obesity with medications?

Surgery is rarely used to treat obesity. Many health professionals will consider it only if you have not been able to lose weight with other treatments and you are at high risk for developing other health problems because of your weight.

If your BMI is over 40, or is 35 or higher and you have a serious medical problem that is made worse by your weight, surgical choices include:

Stomach stapling or gastric banding, both of which make your stomach smaller.
Roux-en-Y bypass or biliopancreatic diversion, both of which make your stomach smaller and limit how much food is absorbed in the small intestine.

Obesity can be prevented. Even if obesity runs in your family, remember that it is the tendency to be obese, not actually becoming obese, that is inherited.

Obesity often begins during the childhood or teen years; studies note that 30% of adult obesity begins in childhood and that being overweight at ages 20 to 22 has been linked with obesity by ages 35 to 37. 4, 10 Developing healthy eating and exercise habits early in life may be the best way to prevent later obesity if you have a family history of excess weight.

The following are general prevention guidelines suitable for people of all ages.

Match the amount of food (how many calories you eat) to your activity level (how many calories you use). If you are uncertain how to do this, a registered dietitian can help. Your health professional or local health department can help you find a dietitian.
Avoid a high-fat diet. A high-fat diet not only provides more calories but also may increase your risk of heart disease. For more information on fat and heart disease, see the topic High Cholesterol.
Develop healthy eating habits, avoid excessive snacking, and do not depend on food to make yourself feel good or to reward yourself.
Get regular, moderate aerobic exercise. Exercise not only helps you lose weight, but also decreases your risk for health problems such as coronary artery disease while you are obese.
Ask your health professional or pharmacist whether medications you are taking make you more likely to gain weight. If so, ask your health professional whether there is another medication you can take that is less likely to result in weight gain.
For more information on preventing weight gain and obesity, see the topic Healthy Eating.

Benefits of weight loss

Research has reported that:

Intentional weight loss may improve survival in obese people who have an obesity-related disease, especially type 2 diabetes. 2
A modest weight loss of 4.4 lb (2 kg) to 9.7 lb (4.4 kg) resulted in a significant lowering of blood pressure. 11
Losing 5 lb (2.3 kg) or more over 16 years was associated with a decrease of 48% (in men) and 40% (in women) in the combination of risk factors for coronary artery disease. These include high blood pressure, triglycerides, cholesterol, blood sugar, body mass index (BMI), and low HDL cholesterol. 2
People with asthma who lost an average of 31.3 lb (14.2 kg) over one year showed improved lung function and overall health, and with weight loss the number of severe asthma episodes (exacerbations) and oral corticosteroid courses were reduced. 12
People with type 2 diabetes who lost weight had lower blood sugar levels and were able to use less medication to lower blood sugar levels. 2
Sustained weight loss prevented new cases of type 2 diabetes in obese people. 2
People with obstructive sleep apnea who lost as little as 10% of their weight improved sleep patterns and had less daytime sleepiness. 2

Treatment for obesity always includes diet and exercise, which can be done at home.

Tips to help with your weight-loss program

Setting realistic goals helps you be satisfied with your weight loss. Many obese people expect to lose much more weight than is realistic. When they do not achieve these goals, it can have a negative effect on self-perception. See questions to consider when setting weight management goals to help you define clear, healthy goals.
Getting family and friends involved provides you with necessary support. Talk to them about why you are changing your diet and activities and how important losing weight is to you. Ask them to help by participating in exercises and having meals with you, even if they may be eating something different.
Self-monitoring identifies obstacles to losing weight, triggers that may lead you to overeat, and irrational thoughts about eating. It also can help you track your progress in modifying your eating behaviors and activity levels.
Understanding the connection between stress and eating can help you determine whether you eat to calm yourself. If so, take action to reduce your stress level.
Managing your environment helps you remove food temptations and, when you do eat, to consume fewer calories.
Understanding and preventing relapse helps you overcome and avoid “falling off” your diet or reverting back to old eating habits. If you feel you have "failed your diet," talk to a family member or friend about it.
Getting enough physical activity burns calories and is especially useful in maintaining your weight.
Tips to help with your eating behavior

Follow a low-calorie diet.
Maintain your diet after you have started it. Consider meal planning to help you eat regular meals and a balanced, nutritious diet. It can also save you money shopping.
Follow tips to cut fat from your diet.
Use lean meats and meat alternatives.
Plan your changes for healthy eating. This provides a road map for how you will make changes and helps you set goals, track your progress, and reward yourself.
Make healthy fast food, restaurant, and convenience food choices to maintain your diet when eating out.
Commercial weight-loss programs

Many commercial weight-loss programs (such as Weight Watchers or LifeSteps) and self-help or support groups (such as Overeaters Anonymous) are available. The quality and effectiveness of these programs vary widely, from reputable obesity clinics associated with hospitals to quick weight-loss schemes that may even harm your health with untested “miracle” products.

One study showed that a structured commercial weight-loss program resulted in more and longer-maintained weight loss over 2 years than in a self-directed program. 13

When considering a commercial weight-loss program, ask questions about the staff's qualifications and whether counseling is offered. Be aware of the advertising strategies for weight-loss programs and products, such as using celebrities and "before and after" pictures.

Most weight-loss medications for obesity work by making you feel less hungry (suppressing your appetite) or making you feel full sooner (satiety). They generally are meant to be used together with diet and exercise; they do not allow you to eat without regard to calories.

Medication generally is used only for those who are obese (a BMI of 30 or higher). However, they sometimes are used for those with a BMI of 27 or higher and having or at risk for high blood pressure, high cholesterol, coronary artery disease, type 2 diabetes, and sleep apnea. 1

Medication Choices

Sibutramine (Meridia) is a prescription medication that makes you feel full sooner.

Orlistat (Xenical) is a prescription medication that prevents some of the fat calories you eat from being absorbed in your intestines.

Phentermine suppresses your appetite. It is rarely used, and is approved only for short-term use.

What To Think About

Phentermine is no longer marketed in Europe due to a possible association with heart and lung problems. 14

Medication alone is not as effective as when combined with diet or activity. Most of the results reported in research are for a combination of medication, diet, and activity.

Medication does not work for everyone. If you do not lose weight within 4 weeks of using medication, the medication probably will not help you. 7

People talking sibutramine and orlistat had weight loss greater than that lost with a placebo only as long as they took the medication. 15

Studies report that when medication is stopped, weight is usually regained. 15

Although current weight-loss medications appear to be safer than previous weight-loss medications, neither their safety (and effectiveness) beyond two years nor their long-term effect on complications or death due to obesity has been established. Side effects still occur. 16

Nonprescription weight-loss products often contain ephedrine and caffeine, which may cause life-threatening heart problems such as increased heart rate and increased blood pressure.

Should I take medications to treat obesity?

Medications no longer available in the United States

From 1992 to 1997, the prescription medications fenfluramine and phentermine were used in combination for the treatment of obesity. This combination was called fen-phen, and it was found to cause serious heart valve problems and was withdrawn from the market at the request of the U.S. Food and Drug Administration (FDA). If you used fen-phen, the FDA strongly suggests you talk with your health professional.

Nonprescription cold remedies and appetite suppressants containing phenylpropanolamine were withdrawn from the market in 2000. It was found that this substance increased the risk of stroke in women.

Surgery is rarely used to treat obesity. Many health professionals will consider it only for people who have not been able to lose weight with other treatments and who are at high risk for developing other health problems because of their weight.

The goal of surgery is to lose about 50% of excess body weight—the weight above what is considered a healthy weight for you. This should reduce or eliminate the risk of diseases associated with obesity, such as type 2 diabetes and high blood pressure. It is important to remember that you may still be obese or overweight after the surgery.

Although guidelines vary, surgery is generally considered when your body mass index (BMI) is 40 or higher, or your BMI is 35 or higher and you have a life-threatening or disabling condition related to your weight.

The following conditions may also be required, or are at least considered:

Have been obese for at least 5 years
Not have a history of alcohol abuse
Not have depression or another major psychiatric disorder
Be between 18 and 65 years of age
Two types of surgery are used to treat obesity. A restrictive operation (such as stomach stapling or adjustable gastric banding) decreases food intake, usually by decreasing the size of the stomach. A malabsorptive operation (such as a Roux-en-Y gastric bypass or a biliopancreatic diversion) restricts food intake and decreases the digestion and absorption of food.

Other types of surgery (including intestinal bypass, jaw wiring, and liposuction) have been used to treat obesity. None have been found to have long-term benefit in the treatment of obesity.

Surgery Choices

Restrictive operations (stomach stapling or gastric banding)
Roux-en-Y gastric bypass
Biliopancreatic diversion (rarely used)
What To Think About

Should I treat obesity with surgery?

All surgeries have risk. Discuss your treatment options with your health professional to decide what is best for your situation.

A Roux-en-Y gastric bypass is the most commonly done surgery for obesity. This is likely because it provides better long-term weight loss than a restrictive operation and less risk than a biliopancreatic diversion.

Most people who have surgery to treat obesity quickly begin to lose weight. Weight loss usually continues for about 2 years.

Risks common to all surgeries for weight loss include an infection in the incision, a leak from the stomach into the abdominal cavity or where the intestine is connected (resulting in peritonitis), and a blockage of blood flow within the lung (pulmonary embolism). About one-third of all people having surgery for obesity develop gallstones or a nutritional deficiency condition such as anemia or osteoporosis. 2, 17

The keys to treating obesity are reducing the amount of calories you eat (eating habits) and increasing the amount of calories your body uses (physical activity).

Commercial weight-loss programs, such as Weight Watchers or LifeSteps, or self-help or support groups, such as Overeaters Anonymous, can help you lose weight. One study showed that a structured commercial weight-loss program resulted in more and longer-maintained weight loss over 2 years than in a self-directed program. 13 Talk with your health professional before beginning a weight-loss program.

When considering a commercial weight-loss program, ask questions about the staff's qualifications and whether counseling is offered. Be aware of the advertising strategies for weight-loss programs and products, such as using celebrities and "before-and-after" pictures.

Online Resources

Aim for a healthy weight
National Heart, Lung, and Blood Institute
Web Address: http://www.nhlbi.nih.gov/health/public/heart/obesity/lose_wt/index.htm

The National Heart, Lung, and Blood Institute (NHLBI) is part of the National Institutes of Health (NIH). This section of its Web site provides useful, medically reviewed information about obesity and weight loss.

Partnership for Healthy Weight Management
Web Address: http://www.consumer.gov/weightloss

The Partnership for Healthy Weight Management is a coalition of representatives from science, academia, the health care profession, government, commercial enterprises, and other organizations. The coalition's mission is to promote sound guidance on strategies for achieving and maintaining a healthy weight. It has produced the “Voluntary Guidelines for Providers of Weight Loss Products or Services” (available on its Web site), which can help consumers choose weight-loss programs or products.

Weight loss and control
National Institute of Diabetes and Digestive and Kidney Diseases
Web Address: http://www.niddk.nih.gov/health/nutrit/nutrit.htm

The National Institute of Diabetes and Digestive and Kidney Diseases maintains this section of its Web site to provide reliable information on eating disorders, nutrition, obesity, and treatment for obesity. It includes a section on helping an overweight child.

Organizations

American Society for Bariatric Surgery
7328 West University Avenue
Suite F
Gainesville, Florida 32607
Phone: (352) 331-4900
Fax: (352) 331-4975
E-mail: info@asbs.org
Web Address: http://www.asbs.org

The American Society for Bariatric Surgery provides information on surgery for obesity, including guidelines for surgery and risks and outcomes of surgery. A body mass index calculator is provided, as well as links to other Web sites and organizations concerned with obesity.

Overeaters Anonymous (OA)
P.O. Box 44020
Rio Rancho, NM 87174-4020
Phone: (505) 891-2664 (or check the white pages for a local number)
Fax: (505) 891-4320
E-mail: info@oa.org
Web Address: http://www.overeatersanonymous.org

Overeaters Anonymous (OA) is a nonprofit international organization that sponsors a 12-step program to help people understand and overcome compulsive eating disorders. OA is not a weight-loss program and makes no claims for weight loss. The program focuses on the psychological and social aspects of overeating.

Shape Up America!
P.O. Box 15757 Crabbs Branch Way
Rockville, MD 20855
Phone: (301) 258-0540
Fax: (301) 258-0541
E-mail: info@shapeup.org
Web Address: http://www.shapeup.org

Shape Up America! is a national coalition of industry and medical experts in nutrition and fitness. Its goals are to make Americans more aware of the importance of maintaining a healthy weight and to provide information about how to lose weight and stay fit. The organization has published several booklets on weight loss and diet which can be ordered from the Web site.

Weight-Control Information Network (WIN)
1 WIN Way
Bethesda, MD 20892-3665
Phone: (202) 828-1025
1-877-946-4627 toll-free
Fax: (202) 828-1028
E-mail: win@info.niddk.nih.gov
Web Address: http://www.niddk.nih.gov/health/nutrit/win.htm

The Weight-Control Information Network (WIN) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health. WIN supplies information on weight control, obesity, and nutritional disorders for the public and for health professionals.