The terms "overweight" and "obesity" refer to body weight that’s greater than what is considered healthy for a certain height.
The most useful measure of overweight and obesity is body mass index (BMI). BMI is calculated from your height and weight. For more information about BMI, go to "How Are Overweight and Obesity Diagnosed?"
Millions of Americans and people worldwide are overweight or obese. Being overweight or obese puts you at risk for many health problems. The more body fat that you have and the more you weigh, the more likely you are to develop:
Your weight is the 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 more.
You can't change some factors, such as family history. However, you can change other factors, such as your lifestyle habits.
For example, follow a healthy eating plan and keep your calorie needs in mind. Be physically active and try to limit the amount of time that you're inactive.
Weight-loss medicines and surgery also are options for some people if lifestyle changes aren't enough.
Reaching and staying at a healthy weight is a long-term challenge for people who are overweight or obese. But it also is a chance to lower your risk for other serious health problems. With the right treatment and motivation, it's possible to lose weight and lower your long-term disease risk.
A lack of energy balance most often causes overweight and obesity. Energy balance means that your energy IN equals your energy OUT.
Energy IN is the amount of energy or calories you get from food and drinks. Energy OUT is the amount of energy your body uses for things like breathing, digesting, and being physically active.
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.
Overweight and obesity happen over time when you take in more calories than you use.
Many Americans aren't very physically active. One reason for this 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, fewer physical demands at work or at home because of modern technology and conveniences, and lack of physical education classes in schools.
People who are inactive are more likely to gain weight because they don't burn the calories that they take in from food and drinks. An inactive lifestyle also raises your risk for coronary heart disease, high blood pressure, diabetes, colon cancer, and other health problems.
Our environment doesn't support healthy lifestyle habits; in fact, it encourages obesity. Some reasons include:
Studies of identical twins who have been raised apart show that genes have a strong influence on a person'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, a link exists between genes and the environment.
Children adopt the habits of their parents. A child who has overweight parents who eat high-calorie foods and are inactive will likely become overweight too. However, if the family adopts healthy food and physical activity habits, the child's chance of being overweight or obese is reduced.
Some hormone problems may cause overweight and obesity, such as underactive thyroid (hypothyroidism), Cushing's syndrome, and polycystic ovarian syndrome (PCOS).
Underactive thyroid 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 is a condition in which the body's adrenal glands make too much of the hormone cortisol. Cushing's syndrome also can develop if a person takes high doses of certain medicines, such as prednisone, for long periods.
People who have Cushing's syndrome gain weight, have upper-body obesity, a rounded face, fat around the neck, and thin arms and legs.
PCOS is a condition that affects about 5–10 percent of women of childbearing age. Women who have PCOS often are obese, have excess hair growth, and have reproductive problems and other health issues. These problems are caused by high levels of hormones called androgens.
Certain medicines may cause you to gain weight. These medicines include some corticosteroids, antidepressants, and seizure medicines.
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 these factors can lead to weight gain.
Some people eat more than usual when they're bored, angry, or stressed. Over time, overeating will lead to weight gain and may cause overweight or obesity.
Some people gain weight when they stop smoking. One reason is that food often tastes and smells better after quitting smoking.
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.
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 about 5 pounds during menopause and have more fat around the waist than they did before.
During pregnancy, women gain weight to support their babies’ growth and development. After giving birth, some women find it hard to lose the weight. This may lead to overweight or obesity, especially after a few pregnancies.
Research shows that lack of sleep increases the risk of obesity. For example, one study of teenagers showed that with each hour of sleep lost, the odds of becoming obese went up. Lack of sleep increases the risk of obesity in other age groups as well.
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.
Sleep helps maintain a healthy balance of the hormones that make you feel hungry (ghrelin) or full (leptin). When you don't get enough sleep, your level of ghrelin goes up and your level of leptin goes down. This makes you feel hungrier than when you're well-rested.
Sleep also affects how your body reacts to insulin, the hormone that controls your blood glucose (sugar) level. Lack of sleep results in a higher than normal blood sugar level, which may increase your risk for diabetes.
For more information, go to the Health Topics Sleep Deprivation and Deficiency article.
Being overweight or obese isn't a cosmetic problem. These conditions greatly raise your risk for other health problems.
As your body mass index rises, so does your risk for coronary heart disease (CHD). CHD is a condition in which a waxy substance called plaque (plak) builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your heart.
Obesity also can lead to heart failure. This is a serious condition in which your heart can't pump enough blood to meet your body's needs.
Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps blood. If this pressure rises and stays high over time, it can damage the body in many ways.
Your chances of having high blood pressure are greater if you're overweight or obese.
Being overweight or obese can lead to a buildup of plaque in your arteries. Eventually, an area of plaque can rupture, causing a blood clot to form.
If the clot is close to your brain, it can block the flow of blood and oxygen to your brain and cause a stroke. The risk of having a stroke rises as BMI increases.
Diabetes is a disease in which the body's blood glucose, or blood sugar, level is too high. Normally, the body breaks down food into glucose and then carries it to cells throughout the body. The cells use a hormone called insulin to turn the glucose into energy.
In type 2 diabetes, the body's cells don't use insulin properly. At first, the body reacts by making more insulin. Over time, however, the body can't make enough insulin to control its blood sugar level.
Diabetes is a leading cause of early death, CHD, stroke, kidney disease, and blindness. Most people who have type 2 diabetes are overweight.
If you're overweight or obese, you're at increased risk of having abnormal levels of blood fats. These include high levels of triglycerides and LDL ("bad") cholesterol and low levels of HDL ("good") cholesterol.
Abnormal levels of these blood fats are a risk factor for CHD. For more information about triglycerides and LDL and HDL cholesterol, go to the Health Topics High Blood Cholesterol article.
Metabolic syndrome is the name for a group of risk factors that raises your risk for heart disease and other health problems, such as diabetes and stroke.
You can develop any one of these risk factors by itself, but they tend to occur together. A diagnosis of metabolic syndrome is made if you have at least three of the following risk factors:
Being overweight or obese raises your risk for colon, breast, endometrial, and gallbladder cancers.
Osteoarthritis is a common joint problem of the knees, hips, and lower back. The condition occurs if the tissue that protects the joints wears away. Extra weight can put more pressure and wear on joints, causing pain.
Sleep apnea is a common disorder in which you have one or more pauses in breathing or shallow breaths while you sleep.
A person who has sleep apnea may have more fat stored around the neck. This can narrow the airway, making it hard to breathe.
Obesity hypoventilation syndrome (OHS) is a breathing disorder that affects some obese people. In OHS, poor breathing results in too much carbon dioxide (hypoventilation) and too little oxygen in the blood (hypoxemia).
OHS can lead to serious health problems and may even cause death.
Obesity can cause menstrual issues and infertility in women.
Gallstones are hard pieces of stone-like material that form in the gallbladder. They're mostly made of cholesterol. Gallstones can cause stomach or back pain.
People who are overweight or obese are at increased risk of having gallstones. Also, being overweight may result in an enlarged gallbladder that doesn't work well.
Overweight and obesity also increase the health risks for children and teens. Type 2 diabetes once was rare in American children, but an increasing number of children are developing the disease.
Also, overweight children are more likely to become overweight or obese as adults, with the same disease risks.
Overweight and obesity affect Americans of all ages, sexes, and racial/ethnic groups. This serious health problem has been growing over the last 30 years.
According to the National Health and Nutrition Examination Survey (NHANES) 2009–2010, almost 70 percent of Americans are overweight or obese. The survey also shows differences in overweight and obesity among racial/ethnic groups.
Children also have become heavier. In the past 30 years, obesity has tripled among school-aged children and teens.
According to NHANES 2009–2010, about 1 in 6 American children ages 2–19 are obese. The survey also suggests that overweight and obesity are having a greater effect on minority groups, including Blacks and Hispanics.
Weight gain usually happens over time. Most people know when they've gained weight. Some of the signs of overweight and obesity include:
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 it's a good gauge of your risk for diseases that occur with more body fat.
BMI is calculated from your height and weight. You can use the chart below or the National Heart, Lung, and Blood Institute's (NHLBI's) online BMI calculator to figure out your BMI. Or, you health care provider can measure your BMI.
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. Weight is measured with underwear but no shoes.
Once you've found your weight, move to the very top of that column. This number is your BMI.
This table offers a sample of BMI measurements. If you don't see your height and/or weight listed on this table, go the NHLBI's complete Body Mass Index Table.
|40.0 and above||Extreme obesity|
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. BMI also may underestimate body fat in older people and others who have lost muscle.
Overweight are obesity are defined differently for children and teens than for adults. 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.
For more information about BMI-for-age and growth charts for children, go to the Centers for Disease Control and Prevention's BMI-for-age calculator.
|Less than 5th percentile||Underweight|
|5th percentile to less than the 85th percentile||Healthy weight|
|85th percentile to less than the 95th percentile||Overweight|
|95th percentile or greater||Obese|
Health care professionals also may take your waist measurement. This helps screen for the possible health risks related to 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 increased risk for coronary heart disease and type 2 diabetes. The risk goes up with a waist size that's greater than 35 inches for women or greater than 40 inches for men.
You also can 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.
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 if you 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 can work together to create a treatment plan. The plan may 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:
Successful weight-loss treatments include setting goals and making lifestyle changes, such as eating fewer calories and being physically active. Medicines and weight-loss surgery also are options for some people if lifestyle changes aren't enough.
Setting realistic weight-loss goals is an important first step to losing weight.
Lifestyle changes can help you and your family achieve long-term weight-loss success. Example of lifestyle changes include:
Over time, these changes will become part of your everyday life.
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.
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 add 100 to 200 calories a day.
Very low-calorie diets with fewer than 800 calories a day shouldn't be used unless your doctor is monitoring you.
For overweight children and teens, it's important to slow the rate of weight gain. However, reduced-calorie diets aren't advised unless you talk with a health care provider.
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 is low in saturated fat, trans fat, cholesterol, sodium (salt), and added sugar. Following a healthy eating plan will lower your risk for heart disease and other conditions.
Healthy foods include:
Canola and olive oils, and soft margarines made from these oils, are heart healthy. However, you should use them in small amounts because they're high in calories.
You also can include unsalted nuts, like walnuts and almonds, in your diet as long as you limit the amount you eat (nuts also are high in calories).
The National Heart, Lung, and Blood Institute's "Aim for a Healthy Weight" patient booklet provides more information about following a healthy eating plan.
Foods to limit. Foods that are high in saturated and trans fats and cholesterol raise blood cholesterol levels and also might be high in calories. Fats and cholesterol raise your risk for heart disease, so they should be limited.
Saturated fat is found mainly in:
Trans fat is found mainly in:
Cholesterol mainly is found in:
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 list of ingredients on food packages for added sugars like high-fructose corn syrup. Drinks that contain alcohol also will add calories, so it's a good idea to limit your 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 Facts label on food packages.
Anyone who has eaten out lately is likely to notice how big the portions are. In fact, over the past 40 years, portion sizes have grown significantly. These growing portion sizes have changed what we think of as a normal portion.
Cutting back on portion size is a good way to eat fewer calories and balance your energy IN. Learn how today's portions compare with those from 20 years ago at the National Heart, Lung, and Blood Institute's Portion Distortion Web pages.
Food weight. Studies have shown that we all tend to eat a constant "weight" of food. Ounce for ounce, our food intake is fairly consistent. Knowing this, you can lose weight if you eat foods that are lower in calories and fat for a given amount of food.
For example, replacing a full-fat food product that weighs 2 ounces with a low-fat product that weighs the same helps you cut back on calories. Another helpful practice is to eat foods that contain a lot of water, such as vegetables, fruits, and soups.
Being physically active and eating fewer calories will help you lose weight and keep weight off over time. Physical activity also will benefit you in other ways. It will:
The four main types of physical activity are aerobic, muscle-strengthening, bone strengthening, and stretching. You can do physical activity with light, moderate, or vigorous intensity. The level of intensity depends on how hard you have to work to do the activity.
People vary in the amount of physical activity they need to control their weight. Many people can maintain their weight by doing 150 to 300 minutes (2 hours and 30 minutes to 5 hours) of moderate-intensity activity per week, such as brisk walking.
People who want to lose a large amount of weight (more than 5 percent of their body weight) may need to do more than 300 minutes of moderate-intensity activity per week. This also may be true for people who want to keep off weight that they've lost.
You don't have to do the activity all at once. You can break it up into short periods of at least 10 minutes each.
If you have a heart problem or chronic disease, such as heart disease, diabetes, or high blood pressure, talk with your doctor about what types of physical activity are safe for you. You also should talk with your doctor about safe physical activities if you have symptoms such as chest pain or dizziness.
Children should get at least 60 minutes or more of physical activity every day. Most physical activity should be moderate-intensity aerobic activity. Activity should vary and be a good fit for the child's age and physical development.
Many people lead inactive lives and might not be motivated to do more physical activity. When starting a physical activity program, some people may need help and supervision 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, gardening, and water aerobics.
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.
For more information about physical activity, go to the Department of Health and Human Services "2008 Physical Activity Guidelines for Americans" and the Health Topics Physical Activity and Your Heart article.
Changing your behaviors or habits related to food and physical activity is important for losing weight. The first step is to understand which habits lead you to overeat or have an inactive lifestyle. The next step is to change these habits.
Below are some simple tips to help you adopt healthier habits.
Change your surroundings. You might be more likely to overeat when watching TV, when treats are available at work, or when you're with a certain friend. You also might find it hard to motivate yourself to be physically active. However, you can change these habits.
Keep a record. A record of your food intake and the amount of physical activity that you do each day will help inspire you. You also can keep track of your weight. For example, when the record shows that you've been meeting your physical activity goals, you'll want to keep it up. A record also is 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 approved by the Food and Drug Administration (FDA) might 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. You should only use medicines as part of a program that includes diet, physical activity, and behavioral changes.
Weight-loss medicines might be suitable for adults who are obese (a BMI of 30 or greater). People who have BMIs of 27 or greater, and who are at risk for heart disease and other health conditions, also may benefit from weight-loss medicines.
As of October 2010, the weight-loss medicine sibutramine (Meridia®) was taken off the market in the United States. Research showed that the medicine may raise the risk of heart attack and stroke.
Orlistat (Xenical®) causes a weight loss between 5 and 10 pounds, although some people lose more weight. Most of the weight loss occurs within the first 6 months of taking the medicine.
People taking Xenical need regular checkups with their doctors, especially during the first year of taking the medicine. During checkups, your doctor will check your weight, blood pressure, and pulse and may recommend other tests. He or she also will talk with you about any medicine side effects and answer your questions.
The FDA also has approved Alli®, an over-the-counter (OTC) weight-loss aid for adults. Alli is the lower dose form of orlistat. Alli is 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.
Both Xenical and Alli reduce the absorption of fats, fat calories, and vitamins A, D, E, and K to promote weight loss. Both medicines also can cause mild side effects, such as oily and loose stools.
Although rare, some reports of liver disease have occurred with the use of orlistat. More research is needed to find out whether the medicine plays a role in causing liver disease. Talk with your doctor if you’re considering using Xenical or Alli to lose weight. He or she can discuss the risks and benefits with you.
You also should talk with your doctor before starting orlistat if you’re taking blood-thinning medicines or being treated for diabetes or thyroid disease. Also, ask your doctor whether you should take a multivitamin due to the possible loss of some vitamins.
In July 2012, the FDA approved two new medicines for chronic (ongoing) weight management. Lorcaserin hydrochloride (Belviq®) and Qsymia™ are approved for adults who have a BMI of 30 or greater. (Qsymia is a combination of two FDA-approved medicines: phentermine and topiramate.)
These medicines also are approved for adults with a BMI of 27 or greater who have at least one weight-related condition, such as high blood pressure, type 2 diabetes, or high blood cholesterol.
Both medicines are meant to be used along with a reduced-calorie diet and physical activity.
Some prescription medicines are used for weight loss, but aren't FDA-approved for treating obesity. They include:
Some OTC products claim to promote weight loss. 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 generally aren't recommended. Some of these OTC products include:
Weight-loss surgery might be an option for people who have extreme obesity (BMI of 40 or more) when other treatments have failed.
Weight-loss surgery also is an option for people who have a BMI of 35 or more and life-threatening conditions, such as:
Two common weight-loss surgeries include banded gastroplasty and Roux-en-Y gastric bypass. For gastroplasty, 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.
For gastric bypass, 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. Gastroplasty has few long-term side effects, but you must limit your food intake dramatically.
Gastric bypass has more side effects. They include nausea (feeling sick to your stomach), bloating, diarrhea, and faintness. These side effects are all part of a condition called dumping syndrome. After gastric bypass, you may need multivitamins and minerals to prevent nutrient deficiencies.
Lifelong medical followup is needed after both surgeries. Your doctor also may recommend a program both before and after surgery to help you with diet, physical activity, and coping skills.
If you think you would benefit from weight-loss surgery, talk with your doctor. Ask whether you're a candidate for the surgery and discuss the risks, benefits, and what to expect.
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:
The key to losing more weight or maintaining your weight loss is to continue with lifestyle changes. Adopt these changes as a new way of life.
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. It's also important to make physical activity part of your normal daily routine.
Following a healthy lifestyle can help you prevent overweight and obesity. Many lifestyle habits begin during childhood. Thus, parents and families should encourage their children to make healthy choices, such as following a healthy diet and being physically active.
Make following a healthy lifestyle a family goal. For example:
Led by the National Heart, Lung, and Blood Institute, 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 maintain 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 community groups 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.
® We Can! is a registered trademark of the U.S. Department of Health and Human Services.
The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.
NHLBI-supported research has led to many advances in medical knowledge and care. For example, this research has uncovered some of the causes of various diseases and conditions, as well as ways to prevent, diagnose, or treat them.
The NHLBI continues to support research aimed at learning more about various diseases and conditions, including overweight and obesity. For example, NHLBI-supported research on overweight and obesity includes studies that:
Much of this research depends on the willingness of volunteers to take part in clinical trials. Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions.
For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.
By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.
If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.
If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.
For more information about clinical trials related to overweight and obesity, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:
For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.
™ Keep the Beat is a trademark of HHS.
® We Can! is a registered trademark of HHS.
The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.