Overweight and Obesity in Adults

Overview

Many adults in the United States have obesity. Obesity is most common in non-Hispanic Black adults, followed by Hispanic adults and non-Hispanic White adults. Non-Hispanic Asian adults have lower obesity rates, although they may have increased risk for obesity-linked diseases at lower weights. There is a higher percentage of obesity among women. Obesity is more common among people living in rural areas than among those who live in urban areas. In addition to dramatic increases in recent years in the number of people with obesity, the average Body Mass Index (BMI, an estimation of excess fat) among people with obesity is also increasing.

Once thought to be due to a lack of self-control, obesity is now known to be a chronic disease where several factors play a role in gaining and retaining excess weight. These include diet, physical activity, and genetics. Social factors such as having access to healthy, affordable food; safe spaces for physical activity; housing; education; healthcare; and other resources also play a role in the risk for obesity. Unfortunately, even though progress has been made toward treating people of all sizes with respect and dignity, weight bias continues to cause a great deal of stress, anxiety and avoidance of getting needed medical care.

Obesity can increase the risk of numerous health problems and lower overall quality of life. Obesity carries greater health risks than having overweight. However, overweight can also increase the risk for certain health problems, and it can lead to obesity.

There are several prevention and treatment approaches for managing obesity, including a healthier diet and more exercise, medicines, and surgery. The treatment plan should fit the person's specific needs and health risks. For some adults, losing just 5% to 10% of starting weight and keeping it off can greatly improve health, including preventing or improving other diseases associated with obesity.

For information about children, visit the Overweight and Obesity in Children page.

Related Health Effects

The main reason to maintain a healthy weight is because overweight and obesity can contribute to a variety of health problems, in children as well as adults. Although many people with overweight and obesity are healthy, these problems become more common the longer a person has obesity.

High Blood Pressure

In people with higher body weight, the heart needs to pump harder to supply blood to all cells. Excess fat may also damage the kidneys, which help regulate blood pressure. High blood pressure can strain the heart, damage blood vessels, and raise the risk of heart attack, stroke, kidney disease, and death.

Cardiovascular Disease and Stroke

In addition to high blood pressure, having overweight or obesity increases the risk of developing high blood cholesterol and triglycerides (fat) and high blood sugar, all of which can contribute to developing heart disease.  Heart disease is the leading cause of death in the US. Heart diseases caused by obesity include heart attacks, heart failure, chest pain and irregular heartbeats. High blood pressure due to obesity and overweight can also lead to strokes. A stroke happens when a blood vessel in the brain or neck is blocked or bursts, cutting off blood flow to a part of the brain.

Type 2 Diabetes

Type 2 diabetes happens when your body has trouble controlling blood sugar because it cannot use insulin properly (insulin resistance) or because it does not make enough insulin. Obesity can contribute to the development of diabetes by reducing the body’s ability to use the hormone insulin, which tells the body to take up sugar from the blood. Over time, high blood sugar can lead to heart disease, stroke, kidney disease, eye problems, nerve damage, and other health problems. The good news is that losing just 5% to 7% of body weight can help prevent or delay type 2 diabetes.

Fatty Liver Diseases

Fatty liver disease develops when fat builds up in the liver, and can progress to severe liver damage or even liver failure in a small fraction of people. Fatty liver is very common in people who are overweight or obese, and for many it can be reversed or improved through weight loss.

Cancer

Overweight and obesity may raise the risk of developing some types of cancer. Also, obesity may affect how a cancer progresses, increase the chances that cancer will come back after treatment, and influences how long somebody survives after cancer diagnosis.

Men with overweight or obesity are at a higher risk for developing cancers of the colon, rectum, and prostate. Among women with overweight or obesity, cancers of the breast, lining of the uterus, and gallbladder are more common.

Breathing Problems

Overweight and obesity can affect how well the lungs work, increasing the risk for breathing problems. Obesity is a common cause of sleep apnea in adults. Sleep apnea is when your breathing stops and restarts many times while you sleep. This can prevent your body from getting enough oxygen. Obesity increases the risk for sleep apnea because more fat stored around the neck can make the airway smaller. Obesity can also increase the risk of developing asthma, worsen asthma symptoms, and make asthma harder to manage.

Osteoarthritis

Osteoarthritis is a degenerative disease, in which the tissues in the joint break down over time. Obesity is a leading risk factor for osteoarthritis in the knees, hips, and ankles, due to extra pressure on joints and on cartilage, the flexible tissue that cushions the joints. Excess body fat may also lead to higher levels of substances in the blood that cause inflammation in the joints, which then raises the risk for osteoarthritis.

Gallbladder and Pancreas Diseases

People who have obesity may have higher levels of cholesterol in their bile, a substance produced in the liver that helps the body digest fats. This can cause gallstones, which are hard, pebble-like pieces of material that develop in the gallbladder. When gallstones block the bile ducts, they can cause sudden pain. People who have obesity also have a higher risk of developing painful inflammation of the pancreas, called pancreatitis. Both of these conditions require immediate medical attention.

Chronic Kidney Disease

Obesity, diabetes and high blood pressure are the most common causes of chronic kidney disease. Obesity may also cause the kidneys to fail more quickly in people with chronic kidney disease.

Pregnancy Complications

Pregnant women who have obesity may have a greater chance of developing gestational diabetes, a form of diabetes that develops during pregnancy and usually goes away afterwards. They also are more likely to have high blood pressure during pregnancy, a dangerous condition known as preeclampsia. In addition, they have higher chances of needing a caesarean delivery and of having complications from surgery and anesthesia.

Fertility Problems

Obesity increases the risk of developing infertility for both men and women. It is linked to lower sperm count and sperm quality in men. In women, obesity is linked to problems with the menstrual cycle and ovulation. It can also make certain infertility treatments or procedures less likely to work.

Sexual Function Problems

Having overweight or obesity increases the risk of developing erectile dysfunction (ED). Few studies have looked at how obesity may affect female sexual function.

Mental Health and Emotional Wellbeing

Weight problems don't just affect the body, they can affect how a person feels, too. Although weight discrimination is becoming less acceptable, some people who carry extra weight still face unfair treatment or judgment from others, which can lead to stress, low self-esteem, anxiety, depression or eating disorders. These can lead to a lower quality of life. Sometimes a history of childhood trauma, such as emotional neglect, divorce, or substance misuse, contributes to overweight and obesity. It is important for people to get professional help for these issues and make sure that mental health is taken care of as well as physical health.

Immunological Effects

Several studies show that some diseases that involve the immune system can be more severe in obese patients, such as infectious or autoimmune diseases. Those patients may also be more resistant to therapies that are effective in patients with a lower body weight.

Causes and Risk Factors

When a person eats more calories than they use, overweight and obesity can develop. The extra calories that are not used are stored as fat in the body. Although obesity is often attributed to unhealthy dietary habits and lack of physical activity and self-control, the truth is more complicated. The number of calories that a person burns each day is unique to the individual, and depends on things like body size, muscle mass, temperature, fitness and physical activity. The stage of life makes a difference as well, as people burn more calories when growing or pregnant, and fewer as they age. The complex processes by which the body converts food into energy can be influenced by type of food, time of day, and genetics, among many other factors. The number of calories people eat can also be influenced by many factors including hunger, habit, social setting, food appearance, aroma and portion size, food advertising, and how much sleep they get. Unfortunately, the drive to eat food is not always tightly linked to the number of calories that are needed for daily life.

Food and Activity

Unhealthy eating habits can result in consuming too many calories, leading to overweight and obesity. These include eating too much food that is high in calories, sugar and fat. Sugary drinks can add a lot of calories without helping you feel full. A healthy diet is one that includes a variety of vegetables, fruits, whole grains, dairy foods, lean meats, fish, beans, and nuts. The amount of food, or portion size, is also important, as well as limiting foods high in fat and added sugar. Learning about a healthy diet is an important part of reaching and keeping a healthy weight.

Sitting for long periods and getting too little physical activity can raise the risk of weight gain. Too much time watching TV, being on the phone or computer, or playing video games is associated with overweight and obesity. Daily activities such as walking can help with weight management.

Poor Sleep

Poor sleep is linked to a higher BMI. Most adults need 7 to 9 hours of sleep each night, though needs vary. Too little sleep may affect hunger and make it harder to notice when you are full.

Stress

Both long- and short-term stress can affect the brain and trigger the body to make hormones, such as cortisol, that alter energy balance and hunger. Therefore, some people eat more than usual when they are bored, angry, upset, or stressed.

Communities and Environments

None of us are completely isolated from external influences. Many aspects of the world around us impact our ability to maintain a healthy weight in ways that we are not completely aware of. It makes sense that not having access to safe parks, sidewalks, and affordable spaces to exercise make it hard for people to be physically active. Oversized food portions in restaurants obviously increase calorie intake, but so do food advertising and the ready availability of inexpensive high-fat snacks and sugary drinks in attractive colorful packages. Indeed, people living in neighborhoods with more fast-food restaurants and inaccessible or no sidewalks or bike paths are more likely to have overweight or obesity. Modern environments make our lives easier in many ways, but they also make it harder to control our dietary choices and calorie intake, and get enough physical activity to be healthy.

Genetics and Family History

Research shows that genetics plays a role in obesity—if parents have obesity, especially during conception and pregnancy, it is more likely that their children will have it too. In rare cases, a mutation in a single gene directly causes obesity in such disorders as Prader-Willi syndrome. Much more commonly, people with obesity will have several genes that do not directly cause obesity, but together make it more likely. In fact, researchers have identified over a thousand places in the genome that appear to be associated with obesity. However, genetic risk doesn’t mean that person will have obesity or overweight. A lifestyle that includes a healthy diet without excess calories and routine exercise will help lower that risk.

Health Conditions

Some hormone problems may cause or increase the likelihood of developing overweight and obesity. These conditions include having an underactive thyroid, Cushing syndrome, and polycystic ovary syndrome (PCOS). There are also eating disorders such as binge-eating disorder and bulimia nervosa which can lead to obesity or weight gain.

Medicines

Some medicines cause weight gain by disrupting the chemical signals that tell the brain a person is hungry or by making it harder for the body to burn calories. These include some antidepressants and antipsychotics, beta-blockers (used to treat high blood pressure), and steroid-based drugs (glucocorticoids), which are often used to treat autoimmune disease. Some drugs used to treat diabetes can cause weight gain, such as insulin and sulfonylureas. A doctor may be able to recommend a similar drug that does not affect weight.

Environmental Chemicals (Obesogens)

There is currently considerable research underway exploring whether chemical pollutants in the environment can cause obesity. Such obesogens might be more disruptive during fetal or early childhood development. Examples of chemical compounds under study include Bisphenol A (BPA) found in many plastic products, flame retardants, pesticides and insecticides such as DDT, phthalates, polychlorinated biphenyls (PCBs), and tributyltin.

Diagnosis

The most common way to determine if a person has overweight or obesity is to calculate BMI, which is an estimate of body fat. BMI is defined as the body mass (in kilograms) divided by the square of the body height (in meters) and expressed in units of kg/m2. An adult's BMI can be determined using a BMI calculator. For adults ages 20 and older, BMI classifications are:

Healthcare providers use BMI, along with information about additional risk factors, to determine a person's risk for developing weight-related diseases. Usually, the higher a person's BMI, the higher the risk of disease. Always talk to a healthcare provider about what your BMI means for your overall health.

It is important to remember that although BMI is a common way to estimate how much body fat a person has, it does not measure body fat directly and does not account for factors like muscle, bone, and body water, which may also contribute to excess weight. As a result, it is not reliable in all cases. In addition, health risks can be higher for a given BMl for Asian racial or ethnic groups.

Knowing your waist size also helps tell if a person has excess body fat or an unhealthy distribution of body fat, because extra fat around the abdomen increases the risk for certain health problems. A waist circumference of more than 35 inches for women or more than 40 inches for men increases the risk for heart disease and type 2 diabetes. To correctly measure waist circumference, stand and place a tape measure around the middle, just above the hipbones, and measure just after breathing out.

Body fat can also be estimated using the thickness of a skinfold (a pinch of skin and fat). Doctors may also use technology such as ultrasound or bioelectrical impedance analysis (BIA) that are more precise than BMI or waist circumference for assessing body fat. A healthcare provider can help determine if such tests are necessary. There are also commercially available personal BIA devices and photo-based apps for smart phones that can be used for home-based estimation of body fat.

Treatment and Management

If diagnosed with overweight or obesity, a person and their healthcare provider can work together to develop a treatment plan. It should address both weight loss and keeping the weight off over time. The goal of the treatment plan is to reduce the risk of obesity-related diseases and maximize quality of life. Obesity diagnosis, counseling, and weight-loss programs may be covered by insurance.

There are many ways to treat obesity, and there is no one correct approach. The important thing is to choose a treatment plan that best suits the individual. All include potentially major changes to daily routine, which can impact family and work life, and all tend to be more successful with professional support. A provider who listens to you can help weigh the benefits and risks of each choice.

With any weight loss program, a person will start to lose weight quickly, but weight loss will slow over time and eventually stop as the body adjusts to the new eating and activity patterns. Keeping the weight off often takes ongoing support and habits that you can maintain long-term. If your plan is not working, talk with your provider about other options.

Consider asking your provider:

• What is a healthy weight for me?
• Is my current weight putting me at risk for other conditions?
• Do any of my medicines or health conditions affect my weight?
• What kind of physical activity or exercise routine should I follow?
• Are there any weight loss groups or plans you suggest?
• Would any medicines or surgery help with my weight management?
• How often should I follow up with you?

Behavioral Weight-Loss Programs

Your doctor may refer you to an individual or group behavioral weight-loss programs where a team of trained healthcare professionals, such as a registered dietitian and nutritionist (RDN), psychologist, or exercise physiologist, will work with the patient to develop a customized weight-loss plan. The plan will likely include a reduced-calorie diet, physical activity goals, and behavioral strategies to stick to those goals over the long run.
Safe and successful weight-loss programs typically include:

• 14 or more weight-loss counseling sessions conducted over 6 months
• An eating plan that meets your nutritional needs and includes foods that you enjoy and can afford
• A plan to build up to at least 150 to 300 minutes per week of moderate-intensity aerobic physical activity, such as brisk walking or cycling
• Daily monitoring of food intake and physical activity, and weekly monitoring of weight
• Regular feedback and support from specialists

When choosing a behavioral weight-loss program, consider whether the program offers the services of multiple professionals, provides customized goals, provides individual or group counseling, and teaches long-term strategies to deal with problems that can lead to future weight gain.

Medicines

When healthy lifestyle changes are not enough, a provider may treat overweight and obesity with medicines. There are now many anti-obesity medicines available, but not all of them are approved by the Food and Drug Administration (FDA), and there are a lot of unofficial sources of approved drugs that may not provide the right drug in the right doses. 

It is very important to work with a trusted healthcare provider and make sure that you only use drugs from a trusted source and an approved manufacturer. Most of the approved drugs reduce hunger, either by acting directly on the brain or by slowing food absorption in the gut. Almost all of them are associated with side effects and should only be started under the supervision of a healthcare provider who will increase the dose slowly in order to reduce unpleasant experiences and optimize the likelihood of sticking with them. Some people may not experience substantial weight loss with one drug and may want to switch to another with a different mechanism of action. It is important to understand that most people who stop taking anti-obesity medicines regain at least some of the weight that was lost and this should be discussed with a doctor before starting treatment. 

Weight-loss medicines should be combined with lifestyle changes for the best chance of losing weight and maintaining the reduced weight long-term.

Surgery

Weight-loss surgery, also called metabolic and bariatric surgery, includes several types of operations that help a person lose weight by making changes to the organs of the digestive system. A doctor may recommend weight-loss surgery if a person has a BMI of 35 or higher. Some doctors and professional groups recommend weight-loss surgery for people with a lower BMI if they have a serious health problem related to obesity, such as type 2 diabetes or sleep apnea.
The most common types of weight-loss surgeries include:

Vertical Sleeve Gastrectomy

A surgeon removes a big portion of the stomach to reduce the amount of food that can be eaten and produce early satiety (or fullness)

Gastric Bypass Surgery

A surgeon creates a small stomach pouch and connects it to the middle part of the intestine. This bypasses the majority of the stomach and the first part of the intestine, reducing the amount of food that can be eaten

Although these procedures are highly effective for the treatment of obesity, some people may experience complications from the surgery or regain their weight over time.

Maintaining a Healthy Weight

Maintaining a healthy weight for the long term is challenging, and it is important to continue the treatment plan and adopt healthy lifestyle changes that can be maintained for life. As with other chronic diseases, long-term treatment with medicines or surgery may be needed to maintain weight loss and reductions in obesity-related conditions.

Healthy Eating

Following a healthy eating plan can help you achieve and maintain a healthy weight. See our health information page on healthy eating for more information.

Physical Activity

Being physically active and reducing sedentary behavior is an important way to help reduce the risk of overweight and obesity and maintain a healthy weight. It is recommended that adults engage in at least 150 to 300 minutes a week of aerobic activity and do muscle-strengthening activities for major muscle groups on 2 or more days each week.

Good-Quality Sleep

Experts recommend 7 to 9 hours of sleep per night for adults. To help get the recommended amount of sleep, create a relaxed bedtime routine, avoid computers and phones an hour before bedtime, avoid alcohol or caffeinated beverages or large meals close to bedtime, keep the bedroom dark and cool, and try to wake up and go to sleep at about the same time every day.

Stress Management

Lowering stress can help you reach and stay at a healthy weight. Stress reduction strategies include taking deep breaths, stretching, or meditating; practicing relaxation techniques such as progressive relaxation; taking breaks from stressful information; taking time to do an enjoyable activity; talking about feelings with a trusted friend, family member, counselor, doctor, or faith leader; and participating in a stress management program.

Keeping Track and Setting Goals

• Talk about goals and progress with a health provider.
• Use an app or a journal to record daily food intake and physical activity.
• Weigh yourself frequently, which has been shown to help with long-term weight maintenance.
• Set specific, doable goals, such as "walk 30 minutes, 5 days a week" or "eat a serving of vegetables with each meal."
• Be realistic--don't change too much at once, as slow changes lead to success

Staying Motivated

• Learn from mistakes. If work, the weather, or family causes an occasional slip, find out what triggered it and restart the eating and physical activity plan.
• Celebrate success by rewarding yourself along the way as goals are met.
• Identify temptations and learn what environments or social activities may prevent you from meeting your goals.

Social Support

Losing weight and managing a healthy weight can be challenging, but having social support and personal networks can help. Try joining a weight loss program with a buddy or ask a friend or family member to join you on your journey. Plan regular physical activity with a friend, as you are more likely to stick with an activity if you and a friend have committed to it together. Support from family and friends can also help relieve stress and anxiety.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find NIH clinical trials on overweight and obesity.

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.

NIH conducts and supports research on obesity and overweight and on many associated disorders. Multiple NIH Institutes and Centers work together as part of the NIH Obesity Research Task Force to address the obesity epidemic in the U.S.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.