What Are Overweight and Obesity?

The terms “overweight” and “obesity” refer to a person’s overall body weight and where the extra weight comes from. Overweight is having extra body weight from muscle, bone, fat, and/or water. Obesity is having a high amount of extra body fat. The most useful measure of overweight and obesity is the body mass index (BMI). BMI is based on height and weight and is used for adults, children, and teens.

Millions of Americans and people worldwide are overweight or obese. Being overweight or obese puts you at risk for many diseases and conditions. The more body fat that you carry around and the more you weigh, the more likely you are to develop heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems, and certain cancers.

A person’s weight is a result of many factors. These factors include environment, family history and genetics, metabolism (the way your body changes food and oxygen into energy), behavior or habits, and other factors.

Certain things, like family history, can’t be changed. However, other things—like a person’s lifestyle habits—can be changed. You can help prevent or treat overweight and obesity if you:

• Follow a healthful diet, while keeping your calorie needs in mind
• Are physically active
• Limit the time you spend being physically inactive

Weight loss medicines and surgery also are options for some people who need to lose weight if lifestyle changes don’t work.

Outlook

Reaching and staying at a healthy weight is a long-term challenge for people who are overweight or obese. But it also can be a chance to lower your risk of other serious health problems. With the right treatment and motivation, it’s possible to lose weight and lower your long-term disease risk.

What Causes Overweight and Obesity?

Energy Balance

For most people, overweight and obesity are caused by not having energy balance. Weight is balanced by the amount of energy or calories you get from food and drinks (this is called energy IN) equaling the energy your body uses for things like breathing, digesting, and being physically active (this is called energy OUT).

Energy balance means that your energy IN equals your energy OUT. To maintain a healthy weight, your energy IN and OUT don’t have to balance exactly every day. It’s the balance over time that helps you maintain a healthy weight.

• The same amount of energy IN and energy OUT over time = weight stays the same
• More IN than OUT over time = weight gain
• More OUT than IN over time = weight loss

Overweight and obesity happen over time when you take in more calories than you use.

Other Causes

Physical Inactivity

Many Americans aren’t very physically active. There are many reasons for this. One reason is that many people spend hours in front of TVs and computers doing work, schoolwork, and leisure activities. In fact, more than 2 hours a day of regular TV viewing time has been linked to overweight and obesity.

Other reasons for not being active include: relying on cars instead of walking to places, fewer physical demands at work or at home because modern technology and conveniences reduce the need to burn calories, and lack of physical education classes in schools for children.

People who are inactive are more likely to gain weight because they don’t burn up the calories that they take in from food and drinks. An inactive lifestyle also raises your risk for heart disease, high blood pressure, diabetes, colon cancer, and other health problems.

Environment

Our environment doesn’t always help with healthy lifestyle habits; in fact, it encourages obesity. Some reasons include:

• Lack of neighborhood sidewalks and safe places for recreation. Not having area parks, trails, sidewalks, and affordable gyms makes it hard for people to be physically active.
• Work schedules. People often say that they don’t have time to be physically active given the long hours at work and the time spent commuting back and forth to work.
• Oversized food portions. Americans are surrounded by huge food portions in restaurants, fast food places, gas stations, movie theaters, supermarkets, and even home. Some of these meals and snacks can feed two or more people. Eating large portions means too much energy IN. Over time, this will cause weight gain if it isn’t balanced with physical activity.
• Lack of access to healthy foods. Some people don’t live in neighborhoods that have supermarkets that sell healthy foods such as fresh fruits and vegetables. Or if they do, these items are often too costly.
• Food advertising. Americans are surrounded by ads from food companies. Often children are the targets of advertising for high-calorie, high-fat snacks and sugary drinks. The goal of these ads is to sway people to buy these high-calorie foods, and often they do.

Genes and Family History

Studies of identical twins who have been raised apart show that genes have a strong influence on one’s weight. Overweight and obesity tend to run in families. Your chances of being overweight are greater if one or both of your parents are overweight or obese. Your genes also may affect the amount of fat you store in your body and where on your body you carry the extra fat.

Because families also share food and physical activity habits, there is a link between genes and the environment. Children adopt the habits of their parents. So, a child with overweight parents who eat high-calorie foods and are inactive will likely become overweight like the parents. On the other hand, if a family adopts healthful food and physical activity habits, the child’s chance of being overweight or obese is reduced.

Health Conditions

Sometimes hormone problems cause overweight and obesity. These problems include:

• Underactive thyroid (also called hypothyroidism). This is a condition in which the thyroid gland doesn’t make enough thyroid hormone. Lack of thyroid hormone will slow down your metabolism and cause weight gain. You’ll also feel tired and weak.
• Cushing’s syndrome. This is a condition in which the body’s adrenal glands make too much of the hormone cortisol. Cushing’s syndrome also can happen when people take high levels of medicines such as prednisone for long periods of time. People with Cushing’s syndrome gain weight, have upper-body obesity, a rounded face, fat around the neck, and thin arms and legs.
• Polycystic ovarian syndrome (PCOS). This is a condition that affects about 5 to 10 percent of women of childbearing age. Women with PCOS often are obese, have excess hair growth, and have reproductive and other health problems due to high levels of hormones called androgens.

Medicines

Certain medicines such as corticosteroids (for example, prednisone), antidepressants (for example, Elavil^®), and medicines for seizures (for example, Neurontin^®) may cause you to gain weight. These medicines can slow the rate at which your body burns calories, increase your appetite, or cause your body to hold on to extra water—all of which can lead to weight gain.

Emotional Factors

Some people eat more than usual when they are bored, angry, or stressed. Over time, overeating will lead to weight gain and may cause overweight or obesity.

Smoking

Some people gain weight when they stop smoking. One reason is that food often tastes and smells better. Another reason is because nicotine raises the rate at which your body burns calories, so you burn fewer calories when you stop smoking. However, smoking is a serious health risk, and quitting is more important than possible weight gain.

Age

As you get older, you tend to lose muscle, especially if you’re less active. Muscle loss can slow down the rate at which your body burns calories. If you don’t reduce your calorie intake as you get older, you may gain weight. Midlife weight gain in women is mainly due to aging and lifestyle, but menopause also plays a role. Many women gain around 5 pounds during menopause and have more fat around the waist than they did before.

Pregnancy

During pregnancy, women gain weight so that the baby gets proper nourishment and develops normally. After giving birth, some women find it hard to lose the weight. This may lead to overweight or obesity, especially after a few pregnancies.

Lack of Sleep

Studies find that the less people sleep, the more likely they are to be overweight or obese. People who report sleeping 5 hours a night, for example, are much more likely to become obese compared to people who sleep 7–8 hours a night.

People who sleep fewer hours also seem to prefer eating foods that are higher in calories and carbohydrates, which can lead to overeating, weight gain, and obesity over time. Hormones that are released during sleep control appetite and the body’s use of energy. For example, insulin controls the rise and fall of blood sugar levels during sleep. People who don’t get enough sleep have insulin and blood sugar levels that are similar to those in people who are likely to have diabetes.

Also, people who don’t get enough sleep on a regular basis seem to have high levels of a hormone called ghrelin (which causes hunger) and low levels of a hormone called leptin (which normally helps to curb hunger).

What Are the Health Risks of Overweight and Obesity?

Being overweight or obese isn’t a cosmetic problem. It greatly raises the risk in adults for many diseases and conditions.

Overweight and Obesity-Related Health Problems in Adults

Heart Disease

This condition occurs when a fatty material called plaque (plak) builds up on the inside walls of the coronary arteries (the arteries that supply blood and oxygen to your heart). Plaque narrows the coronary arteries, which reduces blood flow to your heart. Your chances for having heart disease and a heart attack get higher as your body mass index (BMI) increases. Obesity also can lead to congestive heart failure, a serious condition in which the heart can’t pump enough blood to meet your body’s needs.

High Blood Pressure (Hypertension)

This condition occurs when the force of the blood pushing against the walls of the arteries is too high. Your chances for having high blood pressure are greater if you’re overweight or obese.

Stroke

Being overweight or obese can lead to a buildup of fatty deposits in your arteries that form a blood clot. If the clot is close to your brain, it can block the flow of blood and oxygen and cause a stroke. The risk of having a stroke rises as BMI increases.

Type 2 Diabetes

This is a disease in which blood sugar (glucose) levels are too high. Normally, the body makes insulin to move the blood sugar into cells where it’s used. In type 2 diabetes, the cells don’t respond enough to the insulin that’s made. Diabetes is a leading cause of early death, heart disease, stroke, kidney disease, and blindness. More than 80 percent of people with type 2 diabetes are overweight.

Abnormal Blood Fats

If you’re overweight or obese, you have a greater chance of having abnormal levels of blood fats. These include high amounts of triglycerides and low-density lipoprotein (LDL) cholesterol (a fat-like substance often called “bad” cholesterol), and low high-density lipoprotein (HDL) cholesterol (often called “good” cholesterol). Abnormal levels of these blood fats are a risk for heart disease.

Metabolic Syndrome

This is the name for a group of risk factors linked to overweight and obesity that raise your chance for heart disease and other health problems such as diabetes and stroke. A person can develop any one of these risk factors by itself, but they tend to occur together. Metabolic syndrome occurs when a person has at least three of these heart disease risk factors:

• A large waistline. This is also called abdominal obesity or “having an apple shape.” Having extra fat in the waist area is a greater risk factor for heart disease than having extra fat in other parts of the body, such as on the hips.
• Abnormal blood fat levels, including high triglycerides and low HDL cholesterol.
• Higher than normal blood pressure.
• Higher than normal fasting blood sugar levels.

Cancer

Being overweight or obese raises the risk for colon, breast, endometrial, and gallbladder cancers.

Osteoarthritis

This is a common joint problem of the knees, hips, and lower back. It occurs when the tissue that protects the joints wears away. Extra weight can put more pressure and wear on joints, causing pain.

Sleep Apnea

This condition causes a person to stop breathing for short periods during sleep. A person with sleep apnea may have more fat stored around the neck. This can make the breathing airway smaller so that it’s hard to breathe.

Reproductive Problems

Obesity can cause menstrual irregularity and infertility in women.

Gallstones

These are hard pieces of stone-like material that form in the gallbladder. They’re mostly made of cholesterol and can cause abdominal or back pain. People who are overweight or obese have a greater chance of having gallstones. Also, being overweight may result in an enlarged gallbladder that may not work properly.

Overweight and Obesity-Related Health Problems in Children and Teens

Overweight and obesity also increase the health risks for children and teens. Type 2 diabetes was once rare in American children. Now it accounts for 8 to 45 percent of newly diagnosed diabetes cases. Also, overweight children are more likely to become overweight or obese as adults, with the same risks for disease.

Who Is At Risk for Overweight and Obesity?

Populations Affected

Overweight and obesity affect Americans of all ages, sexes, racial/ethnic groups, and educational levels. This serious health problem has been growing over the years. In fact, overweight and obesity in adults have doubled since 1980, and overweight in children and teens has tripled.

Adults

According to the National Health and Nutrition Examination Survey (NHANES) 2003–2004, about one-third of adults in the United States are overweight and slightly more than one-third are obese. The survey also shows differences in overweight and obesity according to racial/ethnic groups.

• In women, overweight and obesity are highest for non-Hispanic Black women (about 82 percent), compared to about 75 percent for Mexican American women and 58 percent for non-Hispanic White women.
• In men, overweight and obesity also are higher for minority groups. They’re highest for Mexican American men (about 76 percent), compared to about 71 percent for non-Hispanic White men and about 69 percent for non-Hispanic Black men.

Children and Teens

According to NHANES 2003–2004, overweight and the risk for overweight is rising in children and teens. The survey shows that:

• About 19 percent of school-aged children and about 17 percent of teens are overweight.
• About 18 percent of school-aged children and about 17 percent of teens are at risk for overweight.

There are also some differences in overweight according to racial/ethnic groups.

• In male children and teens, overweight is highest for Mexican Americans (about 22 percent), compared to 17 percent for non-Hispanic Whites and about 16 percent for non-Hispanic Blacks.
• In female children and teens, overweight is highest for non-Hispanic Blacks (23 percent), compared to 16 percent for Mexican Americans and about 14 percent for non-Hispanic Whites.

Income

Overweight and obesity are also common in groups with low incomes. Women with low incomes are about 50 percent more likely to be obese than women with higher incomes. Among children and teens, overweight in non-Hispanic White teens is related to a lower family income.

Low-income families also buy more high-calorie, high-fat foods, which may add to the problem. This is because they tend to cost less than more healthful foods such as fruits and vegetables.

What Are the Signs and Symptoms of Overweight and Obesity?

Weight gain usually happens over time. Most people know when they’ve gained weight. Some of the signs of overweight or obesity include:

• Clothes feeling tight and needing a larger size.
• The scale showing that you’ve gained weight.
• Having extra fat around the waist.
• A higher than normal body mass index and waist circumference.

How Are Overweight and Obesity Diagnosed?

The most common way to find out whether you’re overweight or obese is to figure out your body mass index (BMI). BMI is an estimate of body fat and a good gauge of your risk for diseases that occur with more body fat. The higher your BMI, the higher your risk of disease. BMI is calculated from your height and weight.

Body Mass Index for Adults

* Weight is measured with underwear but no shoes.

Use this table to learn your BMI. First, find your height on the far left column. Next, move across the row to find your weight. Once you’ve found your weight, move to the very top of that column. This number is your BMI.

What Does Body Mass Index Mean?

Although BMI can be used for most men and women, it does have some limits:

• It may overestimate body fat in athletes and others who have a muscular build.
• It may underestimate body fat in older persons and others who have lost muscle.

Body Mass Index for Children and Teens

Overweight is defined differently for children and teens than it is for adults. Because children are still growing and boys and girls mature at different rates, BMIs for children and teens compare their heights and weights against growth charts that take age and sex into account. This is called BMI-for-age percentile. A child or teen’s BMI-for-age percentile shows how his or her BMI compares with other boys and girls of the same age.

What Does the BMI-for-Age Percentile Mean?

Waist Circumference

Health care professionals also may take your waist measurement. This helps to screen for the possible health risks that come with overweight and obesity in adults. If you have abdominal obesity and most of your fat is around your waist rather than at your hips, you’re at higher risk for heart disease and type 2 diabetes. This risk goes up with a waist size that is greater than 35 inches for women or greater than 40 inches for men.

You too may want to measure your waist size. To do so correctly, stand and place a tape measure around your middle, just above your hipbones. Measure your waist just after you breathe out.

Specialists Involved

A primary care doctor (or pediatrician for children and teens) will assess your BMI, waist measurement, and overall health risk. If you’re overweight or obese, or have a large waist size, your doctor should explain the health risks and find out whether you’re interested and willing to lose weight. If you are, you and your doctor should work together to create a treatment plan. The plan should include weight loss goals and treatment options that are realistic for you.

Your doctor may send you to other health care specialists if you need expert care. These specialists may include:

• An endocrinologist if you need to be treated for type 2 diabetes or a hormone problem such as an underactive thyroid.
• A registered dietitian or nutritionist to work with you on ways to change your eating habits.
• An exercise physiologist or trainer to figure out your level of fitness and show you how to start physical activities suitable for you.
• A bariatric surgeon if weight loss surgery is an option for you.
• A psychiatrist, psychologist, or clinical social worker to help treat depression or stress.

How Are Overweight and Obesity Treated?

Successful treatments for weight loss include setting goals and making lifestyle changes such as eating fewer calories and being more physically active. Drug therapy and weight loss surgery are also options for some people if lifestyle changes don’t work.

Set Realistic (“Do-able”) Goals

Setting the right weight loss goals is an important first step to losing and maintaining weight.

For Adults

• Lose just 5 to 10 percent of your current weight over 6 months. This will lower your risk for heart disease and other conditions.
• The best way to lose weight is slowly. A weight loss of 1 to 2 pounds a week is do-able, safe, and will help you keep off the weight. It also will give you the time to make new, healthy lifestyle changes.
• If you’ve lost 10 percent of your body weight, have kept it off for 6 months, and are still overweight or obese, you may want to consider further weight loss.

For Children and Teens

• If your child is overweight or at risk of overweight, the goal is to maintain his or her current weight and to focus on eating healthy and being physically active. This should be part of a family effort to make lifestyle changes.
• If your child is overweight and has a health condition related to overweight or obesity, your doctor should refer you to a pediatric obesity treatment center.

Lifestyle Changes

For long-term weight loss success, it’s important for you and your family to make lifestyle changes:

• Focus on energy IN (calories from food and drinks) and energy OUT (physical activity)
• Follow a healthy eating plan
• Learn how to adopt more healthful lifestyle habits

Over time, these changes will become part of your everyday life.

Calories

Cutting back on calories (energy IN) will help you lose weight. To lose 1 to 2 pounds a week, adults should cut back their calorie intake by 500 to 1,000 calories a day.

• In general, 1,000 to 1,200 calories a day will help most women lose weight safely.
• In general, 1,200 to 1,600 calories a day will help most men lose weight safely. This calorie range is also suitable for women who weigh 165 pounds or more or who exercise routinely.

These calorie levels are a guide and may need to be adjusted. If you eat 1,600 calories a day but don’t lose weight, then you may want to cut back to 1,200 calories. If you’re hungry on either diet, then you may want to boost your calories by 100 to 200 a day. Very low-calorie diets of less than 800 calories a day shouldn’t be used unless your doctor is monitoring you.

For overweight children or teens, it’s important to slow the rate of weight gain; however, reduced-calorie diets aren’t advised before you talk to a health care provider.

Healthy Eating Plan

A healthy eating plan gives your body the nutrients it needs every day. It has enough calories for good health, but not so many that you gain weight.

A healthy eating plan also will lower your risk for heart disease and other conditions. A plan low in total, saturated, and trans fat; cholesterol; and sodium (salt) will help to lower your risk for heart disease. Cutting down on fats and added sugars also can help you eat fewer calories and lose weight. Healthful foods include:

• Fat-free and low-fat milk and milk products such as low-fat yogurt, cheese, and milk.
• Lean meat, fish, poultry, cooked beans, and peas.
• Whole grain foods such as whole wheat bread, oatmeal, and brown rice. Other grain foods like pasta, cereal, bagels, bread, tortillas, couscous, and crackers.
• Fruits, which can be canned (in juice or water), fresh, frozen, or dried.
• Vegetables, which can be canned (without salt), fresh, frozen, or dried.

Canola or olive oils and soft margarines made from these oils are heart healthy. They should be used in small amounts because they’re high in calories. Unsalted nuts, like walnuts and almonds, also can be built into a healthful diet as long as you watch the amount you eat, because nuts are high in calories.

Foods to limit. Foods that are high in saturated and trans fats and cholesterol raise blood cholesterol levels and also may be high in calories. These fats raise the risk of heart disease, so they should be limited.

Saturated fat is found mainly in:

• Fatty cuts of meat such as ground beef, sausage, and processed meats such as bologna, hot dogs, and deli meats
• Poultry with the skin
• High-fat milk and milk products like whole-milk cheeses, whole milk, cream, butter, and ice cream
• Lard, coconut, and palm oils found in many processed foods

Trans fat is found mainly in:

• Foods with partially hydrogenated oils such as many hard margarines and shortening
• Baked products and snack foods such as crackers, cookies, doughnuts, and breads
• Food fried in hydrogenated shortening such as french fries and chicken

Cholesterol is found mainly in:

• Egg yolks
• Organ meats such as liver
• Shrimp
• Whole milk or whole-milk products, including butter, cream, and cheese

Limiting foods and drinks with added sugars, like high-fructose corn syrup, is important. Added sugars will give you extra calories without nutrients like vitamins and minerals. Added sugars are found in many desserts, canned fruit packed in syrup, fruit drinks, and nondiet drinks. Check the nutrition label on food packages for added sugars like high-fructose corn syrup. Drinks with alcohol also will add calories, so it’s a good idea to watch alcohol intake.

Portion size. A portion is the amount of food that you choose to eat for a meal or snack. It’s different from a serving, which is a measured amount of food and is noted on the nutrition label on food packages.

Anyone who has eaten out lately is likely to notice how big the portions are. In fact, they’re oversized. These ever-larger portions have changed what we think of as normal.

Cutting back on portion size is a good way to help you eat fewer calories and balance your energy IN.

Food weight. Studies have shown that we all tend to eat a constant “weight” of food. Ounce for ounce, our food intake is fairly constant. Knowing this, you can lose weight if you eat foods that are lower in calories and fat for a given measure of food. For example, replacing a full-fat food product that weighs 2 ounces with one that’s the same weight but lower in fat helps you cut back on calories. Another helpful practice is to eat foods that contain a lot of water like vegetables, fruits, and soups.

Physical Activity

Staying active and eating fewer calories will help you lose weight and keep the weight off over time. Physical activity also will benefit you in other ways. It will:

• Lower the risk of heart disease, diabetes, and cancers (such as breast, uterus, and colon)
• Strengthen your lungs and help them to work better
• Strengthen your muscles and keep your joints in good condition
• Slow bone loss
• Give you more energy
• Help you to relax and cope better with stress
• Allow you to fall asleep more quickly and sleep more soundly
• Give you an enjoyable way to share time with friends and family

In general, adults should follow these guidelines in relation to physical activity.

• For overall health and to lower the risk of disease, aim for at least 30 minutes of moderate-intensity physical activity most days of the week.
• To help manage body weight and prevent gradual weight gain, aim for 60 minutes of moderate-to-vigorous intensity physical activity most days of the week.
• To maintain weight loss, aim for at least 60 to 90 minutes of daily moderate-intensity physical activity.

In general, children and teens should aim for at least 60 minutes of physical activity on most, if not all, days of the week.

Many people lead inactive lives and may not be motivated to do more physical activity. Some people may need help and supervision when they start a physical activity program to avoid injury.

If you’re obese, or if you haven’t been active in the past, start physical activity slowly and build up the intensity a little at a time. When starting out, one way to be active is to do more “everyday” activities such as taking the stairs instead of the elevator and doing household chores and yard work. The next step is to start walking, biking, or swimming at a slow pace, and then build up the amount of time you exercise or the intensity level of the activity.

To lose weight and gain better health, it’s important to get moderate-intensity physical activity. Choose activities that you enjoy and that fit into your daily life. A daily, brisk walk is an easy way to be more active and improve your health. Use a pedometer to count your daily steps and keep track of how much you’re walking. Try to increase the number of steps you take each day.

Other examples of moderate-intensity physical activity include dancing, bicycling, gardening, and swimming. For greater health benefits, try to step up your level of activity or the length of time you’re active. For example, start walking for 10 to 15 minutes three times a week, and then build up to brisk walking for 60 minutes, 5 days a week. You also can break up the amount of time that you’re physically active into shorter amounts such as 15 minutes at a time.

Behavioral Changes

Changing your behaviors or habits around food and physical activity is important for losing weight. The first step is to understand the things that lead you to overeat or have an inactive lifestyle. The next step is to change these habits.

The list below gives you some simple tips to help build healthier habits.

Change your surroundings. You may be more likely to overeat when watching TV, when treats are available in the office break room, or when you’re with a certain friend. You also may not be motivated to take the exercise class you signed up for. But you can change these habits.

• Instead of watching TV, dance to music in your living room or go for a walk.
• Leave the office break room right after you get a cup of coffee.
• Bring a change of clothes to work. Head straight to the exercise class on the way home from work.
• Put a note on your calendar to remind yourself to take a walk or go to your activity class.

Keep a record. A record of your food intake and the amount of physical activity that you do each day will help to inspire you. You also can keep track of your weight. For example, when the record shows that you’ve been meeting your goal to be more active, you’ll want to keep it up. A record is also an easy way to track how you’re doing, especially if you’re working with a registered dietitian or nutritionist.

Seek support. Ask for help or encouragement from your friends, family, and health care provider. You can get support in person, through e-mail, or by talking on the phone. You also can join a support group.

Reward success. Reward your success for meeting your weight loss goals or other achievements with something you would like to do, not with food. Choose rewards that you’ll enjoy, such as a movie, music CD, an afternoon off from work, a massage, or personal time.

Weight Loss Medicines

Weight loss medicines approved by the Food and Drug Administration (FDA) may be an option for some people. If you’re not successful at losing 1 pound a week after 6 months of using lifestyle changes, medicines may help. These medicines should be used only as part of a program that includes diet, physical activity, and behavioral changes.

Weight loss medicines may be suitable for adults who are obese (a BMI of 30 or greater). People who have BMIs of 27 or greater and a risk for heart disease and other health conditions also may benefit from medicines.

The FDA has approved two prescription weight loss medicines for long-term use: sibutramine (Meridia^®) and orlistat (Xenical^®). These medicines cause a weight loss between 4 and 22 pounds, although some people lose more weight. Most of the weight loss occurs within the first 6 months of taking the medicine.

• Sibutramine (Meridia). This medicine sends signals to your brain to curb your appetite. Sibutramine raises blood pressure and pulse. You shouldn’t take it if you have high blood pressure or a history of heart disease or stroke.
• Orlistat (Xenical). This medicine reduces the absorption of fats, fat calories, and vitamins A, D, E, and K by the body. Orlistat can result in mild side effects such as oily and loose stools.

The FDA also has approved Alli™, an over-the-counter weight loss aid for adults. Alli is the lower dose form of orlistat. It’s meant to be used along with a reduced-calorie, low-fat diet and physical activity. In studies, most people taking Alli lost 5 to 10 pounds over 6 months.

Like orlistat, Alli reduces the absorption of fats, fat calories, and vitamins A, D, E, and K to promote weight loss. It also has similar side effects to orlistat. If you’re taking orlistat or Alli, you should take a multivitamin at bedtime due to the possible loss of some vitamins. You also should talk to your doctor before starting Alli if you’re taking blood-thinning medicines or being treated for diabetes or thyroid disease.

Combined with healthy eating and physical activity, these medicines can help people lose weight. If you think you would benefit from the prescription medicines, sibutramine or orlistat, talk to your doctor. People taking these medicines need regular checkups with their doctors, especially in the first year after starting the medicine. During checkups, your doctor will check your weight, blood pressure, and pulse and order laboratory tests. He or she also will discuss any medicine side effects and answer your questions.

Other Medicines

Some prescription medicines are used to treat weight loss, but aren't FDA-approved for treating obesity. They include:

• Drugs to treat depression. Some medicines for depression cause an initial weight loss and then a regain of weight while taking the medicine.
• Drugs to treat seizures. Two drugs used for seizures, topiramate and zonisamide, have been shown to cause weight loss. These drugs are being studied to see whether they will be useful in treating obesity.
• Drugs to treat diabetes. Metformin may cause small amounts of weight loss in people with obesity and diabetes. It’s not known how this drug causes weight loss, but it has been shown to reduce hunger and food intake.

Over-the-Counter Products

Over-the-counter (OTC) products often claim that a person taking them will lose weight. The FDA doesn't regulate these products because they're considered dietary supplements, not medicines. However, many of these products have serious side effects and aren't generally recommended. A few OTC products include:

• Ephedra (also called ma-huang). Ephedra comes from plants and has been sold as a dietary supplement. The active ingredient in the plant is called ephedrine. Ephedra can cause short-term weight loss. It also has serious side effects. It causes high blood pressure and stresses the heart. In fact, because ephedra poses a serious health risk, the FDA has advised people to stop using dietary supplements that contain it.
• Chromium. This is a mineral that's sold as a dietary supplement to reduce body fat. While studies haven't found any weight loss benefit from chromium, there are few serious side effects from taking it.
• Diuretics and herbal laxatives. These products cause you to lose water weight, not fat. They also can lower your body's potassium levels, which may cause heart and muscle problems.
• Hoodia. Hoodia is a cactus that is native to Africa. It's sold in pill form as an appetite suppressant. However, there is no firm evidence that hoodia works. No large-scale research has been done on humans to show whether hoodia is effective or safe.

Weight Loss Surgery

Weight loss surgery may be an option for people with extreme obesity (BMI of 40 or greater) when other treatments have failed. It's also an option for people with a BMI of 35 or greater who have life-threatening conditions such as:

• Severe sleep apnea (a condition in which your breathing stops or gets very shallow while you're sleeping)
• Obesity-related cardiomyopathy (diseases of the heart muscle)
• Severe type 2 diabetes

Two common weight loss surgeries include:

• Banded gastroplasty. For this surgery, a band or staples are used to create a small pouch at the top of your stomach. This surgery limits the amount of food and liquids the stomach can hold.
• Roux-en-Y gastric bypass. For this surgery, a small stomach pouch is created with a bypass around part of the small intestine where most of the calories you eat are absorbed. This surgery limits food intake and reduces the calories your body absorbs.

Weight loss surgery can improve your health and weight. However, the surgery can be risky depending on your overall health. There are few long-term side effects with gastroplasty; however, you must limit your food intake dramatically. Roux-en-Y gastric bypass has more side effects. These include nausea, bloating, diarrhea, and faintness (which are all part of a condition called dumping syndrome). After Roux-en-Y gastric bypass, multivitamins and minerals may be needed to prevent nutrient deficiencies.

Lifelong medical followup is needed after both surgeries. A monitoring program both before and after surgery also is advised to help you with diet, physical activity, and coping skills.

If you think you would benefit from weight loss surgery, talk to your doctor. Ask whether you're a candidate for the surgery and discuss the risks, benefits, and what to expect.

Weight Loss Maintenance

Maintaining your weight loss over time can be a challenge. For adults, weight loss is a success if you lose at least 10 percent of your initial weight and you don't regain more than 6 or 7 pounds in 2 years. You also must keep a lower waist circumference—at least 2 inches lower than your waist circumference before you lost weight.

After 6 months of keeping off the weight, you can think about losing more if:

• You've already lost 5 to 10 percent of your body weight
• You're still overweight or obese

The key to further weight loss or to maintain your weight loss is to continue with lifestyle changes. Adopt these changes as a new way of life. However, if you want to lose more weight, you may need to eat fewer calories and increase your activity level. For example, if you eat 1,600 calories a day but don't lose weight, you may want to cut back to 1,200 calories.

Adults should aim for 60 to 90 minutes of daily moderate-intensity physical activity. Children and teens should aim for 60 minutes of physical activity a day.

How Can Overweight and Obesity Be Prevented?

Staying at a healthy weight and preventing overweight and obesity can be achieved through living a healthy lifestyle. Because lifetime habits begin in childhood, it's important for parents and families to create habits that encourage healthy food choices and physical activity early in life.

• Follow a healthy eating plan. Make healthful food choices, keep your and your family's calorie needs in mind, and focus on the balance of energy IN and energy OUT.
• Focus on portion size. Watch the size of portions in fast food and other restaurants. The portions served are often enough for two or three people. Children's portion sizes should be smaller than those for adults. Cutting back on portion size is a sure way to help keep energy IN and energy OUT in balance.
• Be active. Make personal and family time active. Find activities that everyone will enjoy. For example, go for a brisk walk, bike or rollerblade, or train together for a walk or run.
• Reduce screen time. Limit the use of TVs, computers, DVDs, and video games, because they crowd out time for physical activity. Health experts recommend 2 hours or less a day of screen time that's not work- or homework-related.
• Keep track of weight and other measurements. Monitor your weight, body mass index, and waist circumference on a regular basis. Also, keep track of your children's growth.

Four Institutes from the National Institutes of Health have come together to promote We Can!—Ways to Enhance Children's Activity & Nutrition. We Can! is a national education program designed for parents and caregivers to help children 8 to 13 years old stay at a healthy weight.

The evidence-based program offers parents and families tips and fun activities to encourage healthy eating, increase physical activity, and reduce time spent being inactive. Currently, more than 140 communities around the country are participating in We Can! programs for parents and youth. These community groups include hospitals, health departments, clinics, faith-based organizations, YMCAs, schools, and more.

Key Points

• The terms “overweight” and “obesity” refer to a person’s overall body weight and where the extra weight comes from. Overweight is having extra body weight from muscle, bone, fat, and/or water. Obesity is having a high amount of extra body fat.
• Millions of Americans and people worldwide are overweight or obese.
• Being overweight or obese puts you at risk for many diseases and conditions, including heart disease, high blood pressure, type 2 diabetes, gallbladder disease, breathing problems, and certain cancers.
• A person’s weight is the result of many factors, including environment, family history and genetics, metabolism (the way your body changes food and oxygen into energy), behavior or habits, and other factors.
• For most people, overweight and obesity are caused by not having energy balance. The amount of calories you get from food and drinks is energy IN. The amount of energy your body uses daily is energy OUT. To maintain a healthy weight, energy IN and energy OUT should balance over time.
• Overweight and obesity are calculated using the body mass index (BMI). BMI is an estimate of body fat and a good gauge of your risk for diseases that occur with more body fat.
• Children’s BMI is calculated based on growth charts for their age and sex. This is called BMI-for-age percentile. For more information, go to the Centers for Disease Control and Prevention’s BMI-for-age calculator.
• Treatment for overweight and obesity includes lifestyle changes. These changes mean cutting back on calories, following a healthy eating plan, being physically active, and making behavioral changes.
• When lifestyle changes aren’t enough, other treatment options for some people are weight loss medicines and surgery.
• To manage weight and prevent unhealthy weight gain, adults should aim for 60 minutes of moderate-to-vigorous intensity physical activity most days of the week. To keep up weight loss, aim for 60 to 90 minutes of daily moderate-intensity physical activity.
• Children and teens should strive for 60 minutes of physical activity a day.
• Overweight and obesity in children and teens can be prevented with healthy food choices and more physical activity. Parents and families should create habits that encourage healthful food choices and physical activity early in a child’s life.