Overweight and Obesity

Energy imbalances can cause overweight and obesity. An energy imbalance means that your energy IN does not equal your energy OUT. This energy is measured in calories. Energy IN is the amount of calories you get from food and drinks. Energy OUT is the amount of calories that your body uses for things such as breathing, digesting, being physically active, and regulating body temperature.

Overweight and obesity develop over time when you take in more calories than you use, or when energy IN is more than your energy OUT. This type of energy imbalance causes your body to store fat.

Your body uses certain nutrients such as carbohydrates or sugars, proteins, and fats from the foods you eat to:

• make energy for immediate use to power routine daily body functions and physical activity.
• store energy for future use by your body. Sugars are stored asglycogen in the liver and muscles. Fats are stored mainly as triglyceride in fat tissue.

The amount of energy that your body gets from the food you eat depends on the type of foods you eat, how the food is prepared, and how long it has been since you last ate.

The body has three types of fat tissue—white, brown, and beige—that it uses to fuel itself, regulate its temperature in response to cold, and store energy for future use. Learn about the role of each fat type in maintaining energy balance in the body.

Some genetic syndromes and endocrine disorders can cause overweight or obesity.

Genetic syndromes

Several genetic syndromes are associated with overweight and obesity, including the following.

• Prader-Willi syndrome
• Bardet-Biedl syndrome
• Alström syndrome
• Cohen syndrome

The study of these genetic syndromes has helped researchers understand obesity.

Endocrine disorders

Because the endocrine system produces hormones that help maintain energy balances in the body, the following endocrine disorders or tumor affecting the endocrine system can cause overweight and obesity.

• Hypothyroidism. People with this condition have low levels of thyroid hormones. These low levels are associated with decreased metabolism and weight gain, even when food intake is reduced. People with hypothyroidism also produce less body heat, have a lower body temperature, and do not efficiently use stored fat for energy.
• Cushing’s syndrome. People with this condition have high levels of glucocorticoids, such ascortisol, in the blood. High cortisol levels make the body feel like it is underchronic stress. As a result, people have an increase in appetite and the body will store more fat. Cushing’s syndrome may develop after taking certain medicines or because the body naturally makes too much cortisol.
• Tumors. Some tumors, such as craneopharingioma, can cause severe obesity because the tumors develop near parts of the brain that control hunger.

Medicines such as antipsychotics, antidepressants, antiepileptics, and antihyperglycemics can cause weight gain and lead to overweight and obesity.

Talk to your doctor if you notice weight gain while you are using one of these medicines. Ask if there are other forms of the same medicine or other medicines that can treat your medical condition, but have less of an effect on your weight. Do not stop taking the medicine without talking to your doctor.

Several parts of your body, such as your stomach, intestines, pancreas, and fat tissue, use hormones to control how your brain decides if you are hungry or full. Some of these hormones are insulin, leptin, glucagon-like peptide (GLP-1), peptide YY, and ghrelin.

• Research for Your Health will explain how we are using current research and advancing research to understand, prevent and treat overweight and obesity.
• Risk Factors will discuss family history, lifestyle, or other environmental factors that increase your risk of developing overweight and obesity.

Lack of physical activity, unhealthy eating patterns, not enough sleep, and high amounts of stress can increase your risk for overweight and obesity.

Lack of physical activity

Lack of physical activity due to high amounts of TV, computer, videogame or other screen usage has been associated with a highbody mass index. Healthy lifestyle changes, such as being physically active and reducing screen time, can help you aim for a healthy weight.

Unhealthy eating behaviors

Some unhealthy eating behaviors can increase your risk for overweight and obesity.

• Eating more calories than you use. The amount of calories you need will vary based on your sex, age, and physical activity level. Find out your daily calorie needs or goals with the Body Weight Planner.
• Eating too much saturated and trans fats
• Eating foods high in added sugars

Visit Heart-healthy eating for more information about healthy eating patterns.

Not enough sleep

Many studies have seen a high BMI in people who do not get enough sleep. Some studies have seen a relationship between sleep and the way our bodies use nutrients for energy and how lack of sleep can affect hormones that control hunger urges. Visit our Sleep Deprivation and Deficiency Health Topic for more information about lack of sleep.

High amounts of stress

Acute stress and chronic stress affect the brain and trigger the production of hormones, such as cortisol, that control our energy balances and hunger urges. Acute stress can trigger hormone changes that make you not want to eat. If the stress becomes chronic, hormone changes can make you eat more and store more fat.

Childhood obesity remains a serious problem in the United States, and some populations are more at risk for childhood obesity than others. The risk of unhealthy weight gain increases as you age. Adults who have a healthy BMI often start to gain weight in young adulthood and continue to gain weight until 60 to 65 years old, when they tend to start losing weight.

Many environmental factors can increase your risk for overweight and obesity:  

• social factors such as having a low socioeconomic status or an unhealthy social or unsafe environment in the neighborhood 
• built environment factors such as easy access to unhealthy fast foods, limited access to recreational facilities or parks, and few safe or easy ways to walk in your neighborhood
• exposure to chemicals known as obesogens that can change hormones and increase fatty tissue in our bodies

Genetic studies have found that overweight and obesity can run in families, so it is possible that our genes or DNA can cause these conditions. Research studies have found that certain DNA elements are associated with obesity.

Did you know obesity can change your DNA and the DNA you pass on to your children? Learn more about these DNA changes.

Overweight and obesity is highly prevalent in some racial and ethnic minority groups. Rates of obesity in American adults are highest in blacks, followed by Hispanics, then whites. This is true for men or women. While Asian men and women have the lowest rates of unhealthy BMIs, they may have high amounts of unhealthy fat in the abdomen. Samoans may be at risk for overweight and obesity because they may carry a DNA variant that is associated with increased BMI but not with common obesity-related complications.

In the United States, obesity is more common in black or Hispanic women than in black or Hispanic men. A person’s sex may also affect the way the body stores fat. For example, women tend to store less unhealthy fat in the abdomen than men do.

Overweight and obesity is also common in women with polycystic ovary syndrome (PCOS). This is an endocrine condition that causes large ovaries and prevents proper ovulation, which can reduce fertility.

To screen for overweight and obesity, doctors measure BMI using calculations that depend on whether you are a child or an adult. After reading the information below, talk to your doctor or your child’s doctor to determine if you or your child has a high or increasing BMI.

• Children: A healthy weight is usually when your child’s BMI is at the 5th percentile up to the 85th percentile, based on growth charts for children who are the same age and sex. To figure out your child’s BMI, use the Center for Disease Control and Prevention (CDC) BMI Percentile Calculator for Child and Teen and compare the BMI with the table below.
• Adults: A healthy weight for adults is usually when your BMI is 18.5 to less than 25. To figure out your BMI, use the National Heart, Lung, and Blood Institute’s online BMI calculator and compare it with the table below. You can also download the BMI calculator app for iPhone and Android.

Body mass index (BMI) is used to determine if you or your child are underweight, healthy, or overweight or obese. Children are underweight if their BMI is below the 5th percentile, healthy weight if their BMI is between the 5th to less than the 85th percentile, overweight if their BMI is the 85th percentile to less than the 95th percentile, and obese if their BMI is the 95th percentile or above. Adults are underweight if their BMI is below 18.5, healthy weight if their BMI is 18.5 to 24.9, overweight if their BMI is 25 to 29.9, and obese if their BMI is 30 or above. *A child’s BMI percentile is calculated by comparing your child’s BMI to growth charts for children who are the same age and sex as your child.

If your BMI indicates you are getting close to being overweight, or if you have certain risk factors, your doctor may recommend you adopt healthy lifestyle changes to prevent you from becoming overweight and obese. Changes include healthy eating, being physically active, aiming for a healthy weight, and getting healthy amounts of sleep. Read healthy lifestyle changes for more information

• Diagnosis will explain tests and procedures that your doctor may use to diagnose overweight and obesity.
• Living With will discuss what your doctor may recommend to monitor and prevent your condition from getting worse and to screen you for complications.
• Research for Your Health will explain how we are using current research and advancing research to prevent overweight and obesity.
• Participate in NHLBI Clinical Trials will discuss our open clinical trials that are studying ways to prevent overweight and obesity.

A high BMI is the most common sign of overweight and obesity.

Body mass index (BMI) is used to determine if you or your child are underweight, healthy, or overweight or obese. Children are underweight if their BMI is below the 5th percentile, healthy weight if their BMI is between the 5th to less than the 85th percentile, overweight if their BMI is the 85th percentile to less than the 95th percentile, and obese if their BMI is the 95th percentile or above. Adults are underweight if their BMI is below 18.5, healthy weight if their BMI is 18.5 to 24.9, overweight if their BMI is 25 to 29.9, and obese if their BMI is 30 or above. *A child’s BMI percentile is calculated by comparing your child’s BMI to growth charts for children who are the same age and sex as your child.

Another sign of overweight and obesity is having an unhealthy body fat distribution. Fatty tissue is found in different parts of your body and has many functions. Having an increased waist circumference suggests that you have increased amounts of fat in your abdomen. An increased waist circumference is a sign of obesity and can increase your risk for obesity-related complications.

Did you know that fatty tissue has different functions depending on its location in your body?

Obesity may cause the following complications:

• Metabolic Syndrome
• Type 2 diabetes
• High blood cholesterol and high triglyceride levels in the blood
• Diseases of the heart and blood vessels such as high blood pressure, atherosclerosis, heart attacks and stroke
• Respiratory problems such as obstructive sleep apnea , asthma, and obesity hypoventilation syndrome
• Back pain  
• Non-alcoholic fatty liver disease (NAFLD)
• Osteoarthritis, a chronic inflammation that damages the cartilage and bone in or around the affected joint. It can cause mild or severe pain and usually affects weight-bearing joints in people who are obese. It is a major cause of knee replacement surgery in patients who are obese for a long time.
• Urinary incontinence, the unintentional leakage of urine. Chronic obesity can weaken pelvic muscles, making it harder to maintain bladder control. While it can happen to both sexes, it usually affects women as they age.
• Gallbladder disease
• Emotional health issues such as low self-esteem or depression. This may commonly occur in children.
• Cancers of the esophagus, pancreas, colon, rectum, kidney, endometrium, ovaries, gallbladder, breast, or liver.

Did you know inflammation is thought to play a role in the onset of certain obesity-related complications?

• Diagnosis will explain tests and procedures used to detect signs of overweight and obesity and help rule our other conditions that may be causing weight gain.
• Treatment will discuss treatment-related complications or side effects.
• Living With will explain how doctors use waist circumference to monitor for disease severity and check for complications.

To diagnose overweight and obesity, doctors measure BMI using calculations that depend on whether you are a child or an adult.

• Children: A healthy weight is usually when your child’s BMI is at the 5th percentile up to less than the 85th percentile based on growth charts for children who are the same age and sex. To figure out your child’s BMI, use the Center for Disease Control and Prevention (CDC) BMI Percentile Calculator for Child and Teen and compare the BMI with the table below.
• Adults: A healthy weight for adults is usually when your BMI is 18.5 to less than 25. To figure out your BMI, use the National Heart, Lung, and Blood Institute’s online BMI calculator and compare it with the table below. You can also download the BMI calculator app for iPhone and Android. Even if your BMI is in the healthy range, it is possible to be diagnosed as obese if you have a large waist circumference that suggests increased amounts of fat in your abdomen that can lead to complications.

Body mass index (BMI) is used to determine if you or your child are underweight, healthy, or overweight or obese. Children are underweight if their BMI is below the 5th percentile, healthy weight if their BMI is between the 5th to less than the 85th percentile, overweight if their BMI is the 85th percentile to less than the 95th percentile, and obese if their BMI is the 95th percentile or above. Adults are underweight if their BMI is below 18.5, healthy weight if their BMI is 18.5 to 24.9, overweight if their BMI is 25 to 29.9, and obese if their BMI is 30 or above. *A child’s BMI percentile is calculated by comparing your child’s BMI to growth charts for children who are the same age and sex as your child.

Your doctor will ask about your eating and physical activity habits, family history, and will see if you have other risk factors Your doctor may ask if you have any other signs or symptoms. This information can help determine if you have other conditions that may be causing you to be overweight or obese or if you have complications from being overweight or obese.

During your physical exam, your doctor will measure your weight and height to calculate your BMI. Your doctor may also measure your waist circumference to estimate the amount of unhealthy fat in your abdomen. In adults, a waist circumference over 35 inches for women who are not pregnant or 40 inches for men can help diagnose obesity and assess risk of future complications. If you are of South Asian or Central and South American descent, your doctor may use smaller waist circumference values to diagnose your obesity. People from these backgrounds often don’t show signs of a large waist circumference even though they may have unhealthy amounts of fat deep in their abdomens and may be diagnosed with obesity. Visit Assessing Your Weight for more information.

Read Living With for more information about why it is important to monitor your waist circumference to assess your risk for complications.

Your doctor may order some of the following tests to identify medical conditions that may be causing your overweight and obesity.

• Blood tests. Blood tests that check your thyroid hormone levels can help rule out hypothyroidism as a cause of your overweight or obesity. Cortisol and adrenocorticotropic hormone (ACTH) tests can rule out Cushing’s syndrome. Total testosterone and dehydroepiandrosterone sulphate (DHEAS) tests can help rule out polycystic ovary syndrome (PCOS).
• Pelvic ultrasound to examine the ovaries and detect cysts. This can rule out PCOS.

• Return to Risk Factors to review family history, lifestyle, or other environmental factors that increase your risk of developing overweight and obesity.
• Return to Signs, Symptoms, and Complications to review common signs and symptoms of overweight and obesity.
• Return to Screening & Prevention to review how to screen for overweight and obesity.

To help you aim for and maintain a healthy weight, your doctor may recommend that you adopt lifelong healthy lifestyle changes.

• Heart-healthy eating. Learn about which foods and nutrients are part of a healthy eating pattern. It’s important to eat the right amount of calories to maintain a healthy weight. If you need to lose weight, try to reduce your total daily calories gradually. Use the Body Weight Planner to find out your daily calorie needs and to set goals. Visit healthy recipes and plan for success. Talk with your doctor before beginning any diet or eating plan. Visit Chose My Plate or 2015-2020 Dietary Guidelines for Americans for more information.
• Physical activity. Many health benefits are associated with physical activity and getting the recommended amount of physical activity needed each week. Physical activity is an important factor in determining whether a person can maintain a healthy body weight, lose excess body weight, or maintain successful weight loss. Before starting any exercise program, ask your doctor about what level of physical activity is right for you. Visit Physical Activity Has Many Health Benefits for more information.
• Healthy Sleep. Studies have shown some relationship between lack of sleep and obesity. Read Sleep Deprivation and Deficiency more information.

Making lifelong healthy lifestyle changes, such as heart-healthy eating and physical activity, can help you modify your energy balance to help you aim for and maintain a healthy weight. For example:

• To aim for a healthy weight, or lose weight, you want your energy OUT to be more than your energy IN.

• To maintain weight loss you want your energy IN and energy OUT to be the same. 

Your doctor may recommend you enroll in individual or group behavioral weight-loss programs to treat your overweight and obesity. In these programs, a trained healthcare professional will customize a weight-loss plan for you. This plan will include a moderately-reduced calorie diet, physical activity goals, and behavioral strategies to help you make and maintain these lifestyle changes. Read Living With for more information about required follow-up for these behavioral treatment programs.

Did you know your brain’s pleasure and reward centers can be stimulated by food and the act of eating, making it harder to change eating patterns and lose weight?

When healthy lifestyle changes are not enough, your doctor may treat your overweight and obesity with FDA-approved medicines. These medicines work in the following parts of your body.

• Brain. Several medicines change the way the brain regulates the urge to eat, which can help to decrease appetite. Some examples of these medicines are diethylpropion, phendimetrazine, lorcaserin, naltrexone/bupropion, and liraglutide.
• Gastrointestinal tract. Orlistat is the only available medicine. It blocks your intestines from absorbing fat from foods in your diet.

Weight loss medicines are not recommended as a single treatment for weight loss. These medicines can help you lose weight but when combined with lifestyle changes may result in greater weight loss. Some of these medicines should not be used if you have certain conditions or are taking certain medicines. Also, these medicines have side effects. Talk to your doctor if you are pregnant, planning to get pregnant, breast feeding, or have a family history of cardiovascular diseases such as high blood pressure, heart attack, or stroke.

Some patients with obesity do not respond to healthy lifestyle changes and medicines. When these patients develop certain obesity-related complications, they may be eligible for the following surgeries.

• Gastric bypass surgery. A small part of the stomach is connected to the middle part of the intestine, bypassing the first part of intestine. This decreases the amount of food that you can eat and the amount of fat your body can take in and store.
• Gastrectomy. A big portion of the stomach is removed to decrease the amount of food that you can eat.
• Gastric banding. A hollow band is placed around the upper part of the stomach creating a smaller stomach. This decreases the amount of food you can eat.

Talk to your doctor to learn more about the benefits and risks of each type of surgery. Possible complications include bleeding, infection, internal rupture of sutures, or even death. Read gastric bypass surgery for more information.

Interested in learning why these surgeries lead to weight loss in some patients?

• Living With will explain recommendations that your doctor may give, including lifelong healthy lifestyle changes and medical care to prevent your condition from recurring, getting worse, or causing complications.
• Research for Your Health will explain how we are using current research and advancing research to treat people with overweight and obesity.
• Participate in NHLBI Clinical Trials will discuss our ongoing clinical studies that are investigating treatments for overweight and obesity.

Changing lifestyle habits takes time and patience. Follow these tips to help you maintain the healthy lifestyle changes your doctor recommended to aim for a healthy weight.

• Use our Daily Food and Activity Diary or the United States Department of Agriculture’s online SuperTracker to record your daily food intake and physical activity. You, your doctor, or health care provider can use this diary to monitor your progress.
• Set specific goals. An example of a specific goal is to “walk 30 minutes, 5 days a week". Be realistic about your time and abilities.
• Set doable goals that don’t change too much at once. Consecutive goals that can move you ahead in small steps, are the best way to reach a distant point. When starting a new lifestyle, try to avoid changing too much at once. Slow changes lead to success. Remember, quick weight loss methods do not provide lasting results.
• Learn from your slips. Everyone slips, especially when learning something new. Don’t worry if work, the weather, or your family causes you to have an occasional slip. Remember that changing your lifestyle is a long-term process. Find out what triggered the slip and restart your eating and physical activity plan.
• Celebrate your success. Reward yourself along the way as you meet your goals. Instead of eating out to celebrate your success, try a night at the movies, go shopping for workout clothes, visit the library or bookstore, or go on a hike.
• Identify temptations. Learn what environments or social activities, such as watching TV or going out with friends, may be keeping you from meeting your goals. Once you have identified them, use creative strategies to help keep you on track.  
• Plan regular physical activity with a friend. Find a fun activity that you both enjoy, such as Zumba, jogging, biking or swimming. You are more likely to stick with that activity if you and a friend have committed to it.  

Visit More Information for important NHLBI resources to help you aim for a healthy weight.

Some people find it is easier to aim and maintain a healthy weight when they have support from a weight-loss specialist or other individuals who also are trying to lose weight. Behavioral weight-loss programs can provide this support, and they can help you set goals that are specific to your needs. Your weight-loss specialist usually reviews or modifies your goals every six months based on your progress and overall health.

When you are choosing a behavioral weight-loss program, you may want to consider whether the program should:

• offer the service of multiple professionals, such as registered dietitians, doctors, nurses, psychologists, and exercise physiologists.
• provide goals that have been customized for you that consider things such as the types of food you like, your schedule, your physical fitness, and your overall health.
• provide individual or group counseling to help you change your eating patterns and personal unhealthy habits.
• teach long-term strategies to deal with problems that can lead to future weight gain, such as stress or slipping back into unhealthy habits.

When selecting a program, you may want to ask about:

• the percentage of people who complete the program.
• the average weight loss for people who finish the program.
• possible side effects.
• fees or costs for additional items such as dietary supplements.

You should visit your health care provider periodically to monitor for possible complications, which if left untreated can be life-threatening. Your doctor may do any of the following to monitor your condition.

• Assess your weight loss since your last visit. A weight loss of approximately five percent in an overweight patient may improve the function of the fat tissue and help lower bad cholesterol and other substances that can predispose to complications.
• Measure your waist circumference if you are an adult. If your waist circumference is greater than 35 inches for women or greater than 40 inches for men, you may be at risk for heart disease, stroke, or type 2 diabetes. South Asians and South and Central Americans have a higher risk of complications, so waist circumference should be smaller than 35 for man and 31 for women. To correctly measure your waist, stand and place a tape measure around your middle, just above your hip bones. Measure your waist just after you breathe out. Visit Assessing Your Weight for more information.
• Order blood tests to screen for complications. A lipid panel test can check if you have high cholesterol or triglyceride levels in your blood. A liver function test can determine if your liver is working properly. A fasting glucose test can find out if you have prediabetes or diabetes.

Learn about the following ways NHLBI continues to translate research and science into improved health for people who are overweight or obese.

• NHLBI Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents. We support the development of guidelines based on up-to-date research to evaluate and manage risk of heart disease in children and adolescents, including overweight and obesity. Visit Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents for more information.
• NHLBI Systematic Evidence Reviews Support Development of Guidelines for Overweight and Obese Adults. We continue to perform systematic reviews of the latest science. These reviews help partner organizations update their clinical guidelines, which health professionals use to treat adults who are overweight or obese. Visit Managing Overweight and Obesity in Adults: Systematic Evidence Review from the Obesity Expert Panel for more information.
• NHLBI Obesity Education Initiative. We continue our 20-year long commitment to educating the public and high-risk populations about adopting heart-healthy eating and physical activity for life to prevent and treat overweight and obesity and their associated complications. Visit Obesity Education Initiative for more information.
• NIH Obesity Research Task Force and Strategic Plan. We continue to support this larger NIH task force, that is committed to capitalizing on scientific research discoveries to develop new prevention methods and treatments for overweight and obesity. Visit NIH Obesity Research, NHLBI Obesity Research and the Strategic Plan for NIH Obesity Research for more information.
• NIH task force to develop first nutrition strategic plan. We will collaborate with other institutes to develop a ten-year plan to increase research in nutrition, including experimental design and training. Visit NIH task force formed to develop first nutrition strategic plan for more information.
• Federal Dietary Guidelines for Americans. We continue to provide medical, nutritional, and other scientific expertise to the United States Department of Agriculture (USDA) and the Department of Health and Human Services (HHS) that publish the 2015-2020 Dietary Guidelines for Americans with information about the latest science-based nutritional recommendations.

Learn about some of the pioneering research contributions we have made over the years that have improved clinical care.

In support of our mission, we are committed to advancing overweight and obesity research in part through the following ways.

• We fund research. Our Division of Cardiovascular Sciences, which includes our Clinical Applications and Prevention Branch, funds research to understand how overweight and obesity relate to heart disease. Our Division of Lung Diseases funds research on the impact of overweight and obesity on sleep disordered breathing. The research we fund today will help improve our future health. Search the NIH Research Portfolio Online Reporting Tools (RePORT) to learn about research NHLBI is funding on overweight and obesity.
• We stimulate high-impact research. Our NHLBI Obesity Research continues discovering new insights about obesity that can lead to improved health care, practices, and policies to prevent or treat obesity and its heart, lung, and sleep consequences and translating research into practical strategies and tools for clinicians, patients, and the general public. Our Trans-Omics for Precision Medicine (TOPMed) Program includes participants with overweight and obesity, which may help us understand how genes contribute to overweight and obesity. The NHLBI Strategic Vision highlights ways we may support research over the next decade, including new efforts for overweight and obesity.

Learn more about the exciting research areas we are exploring about overweight and obesity.

Participate in NHLBI Clinical Trials will discuss some of our overweight and obesity clinical trials that are open.