But for the purposes of this guide, we’ll focus on the World Health Organization’s (WHO) definition of obesity: abnormal or excessive fat accumulation in the body that may pose a risk to your health. Below, discover how doctors determine whether someone is obese, as well as causes and risk factors of obesity, treatment options for obesity, and much more. As a medical term, obesity is defined by body mass index, or BMI, according to the Centers for Disease Control and Prevention (CDC). BMI takes both a person’s height and weight into account and is expressed in units of kilograms per square meter (kg/m2). You can also use this formula to get your BMI: Divide your weight in pounds by your height in inches squared. Then multiply the amount by 703.
BMI Ranges
BMI levels for adults are categorized as follows:
Normal weight: 18.5 to 24.9Overweight: 25 to 29.9Obese: 30 or greater
Obesity is further classified as:
Class 1 obesity: 30 to 34.9Class 2 obesity: 35 to 39.9Class 3 obesity: 40 or higher
But keep in mind BMI is extremely limited. When using obesity as a way to measure health risk, the aforementioned ranges may be inappropriate for many groups of people. For instance, “Asians and Asian Americans may have increased health risks at a lower BMI," notes the Joslin Diabetes Center at Harvard University in Boston. Same goes for Black people. An article published by the Harvard T.H. Chan School of Public Health notes that some studies have found that Black people have lower body fat and higher lean muscle mass than white people at the same BMI; meaning that at the same BMI, they may have a lower risk of developing obesity-related diseases. All the same, BMI can be a good starting point as a screening tool, says Ali. But because it takes into account only height and weight, and not muscle composition or other factors, BMI is ultimately an imperfect measurement. Learn More About Obesity and BMI Levels
BMI Calculators
There are many online tools that will calculate your BMI. Adults can use a BMI calculator to determine their BMI. For children, doctors tend to use a percentile system instead. The CDC provides a BMI calculator for children ages 2 through 19. The Joslin Diabetes Center has created a BMI calculator for Asian people, and this resource lowers the beginning point for overweight BMI to 23 and the beginning point for obesity to 27. While there isn’t an adjusted BMI scale for Black people, other methods may be more accurate. An older study, published in 2013 in The Yale Journal of Biology and Medicine (PDF), found that percent body fat measurement could be used to more accurately assess obesity in African American women. Learn More About BMI Calculators
Obesity in Children
Obesity can not only lower quality of life during childhood but may increase the chance that the excess weight will persist into adulthood, says Sheila Perez-Colon, MD, who is a double-board-certified pediatric oncologist and practices at Elite Endocrine MD in San Juan and Dorado, Puerto Rico. Obesity also raises the risk a child will develop obesity-related diseases such as type 2 diabetes, heart disease, high cholesterol, high blood pressure, stroke, and certain types of cancer as an adult. “It could even lead to anxiety and depression,” she adds. The CDC reports that in the United States, obesity affected 19.7 percent of youth ages 2 to 19 in the years 2017 to 2020, and was more prevalent in Hispanic (26.2 percent) and non-Hispanic Black children (24.8 percent) than in non-Hispanic white children (16.6 percent). Parents of children who are developing obesity or its complications may not recognize the warning signs, says Dr. Pérez-Colón. “You see a progressive increase in weight gain, and when plotted in the growth chart, the BMI is increased. You may see what we call central obesity, which is when fat accumulates around the abdominal area. You may also see darkening around the neck known as acanthosis nigricans, which is associated with insulin resistance and an increased risk for diabetes. “Signs or symptoms for diabetes include increased urination, increased thirst, and increased hunger among others.” she adds. “If the child has any of those, it’s important to get evaluated by their doctor.” Learn More About Childhood Obesity Behavior Not getting regular physical activity and having unhealthy eating habits can contribute to obesity risk. Community Environment Living under conditions that do not enable and encourage safe movement and access to healthy food can increase a person’s chances of developing obesity. Childhood adversity, such as maltreatment, is also associated with a higher risk for obesity, as a study published in January 2019 in Translational Psychiatry notes. Other Diseases Cushing’s syndrome, depression, diabetes, and polycystic ovary syndrome (PCOS) are among the disorders that are associated with obesity. Genetics Having one obese parent gives you a 40 percent chance of being obese, and if both your parents are obese your chance is higher at 80 percent, according to an article in the Journal of Clinical Research in Pediatric Endocrinology summarizing studies on identical twins and their parents. But the reasons for developing obesity are complex and involve both inherited predispositions and a shared environment. “Only a very small number of people suffer from known genetic disorders causing severe obesity, and we are contending with an addictive environment that hijacks our evolutionarily designed reward system, making it harder to control when and what we eat,” says Jamie Kane, MD, the director of weight management at Northwell Health in Long Island, New York. Such monogenic disorders can be pinpointed to a single gene variant through testing. MCR4 (melanocortin 4 receptor) gene mutations are the most common among them, he says. The CDC explains that MCR4 changes affect hunger in children and cause a tendency to overeat. Perez-Colon says genes related to leptin (LEP), a hormone produced by fat cells, and leptin receptor (LEPR), which affects appetite, are also sometimes tested for. She recommends genetic counseling for families who have a history of such mutations, as the CDC also notes. Yet the CDC states that in most people with obesity, no single genetic cause can be identified. Drugs Some medications can cause weight gain, such as steroids and certain antidepressants. Race and Ethnicity Being Black or Hispanic is associated with higher risk for obesity compared with white or Asian people. Socioeconomic Status People who don’t have a college degree may have a higher risk of obesity than people who do. Among men, middle-income status puts you at higher risk for obesity; among women, middle or lower income puts you at higher risk. Learn More About Obesity Causes Depending on the physician, they may also take other factors into account before making a final diagnosis, such as muscle composition, says Mir Ali, MD, a bariatric surgeon and the medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, California.
Prognosis of Obesity
Being merely overweight (a BMI of 25 to 29.9) will not necessarily take years off your life, but having class 3 obesity (a BMI of 40 to 44.9) was associated with an estimated shorter life of about 6.5 years compared with people who have a normal weight. People with class 3 obesity who had even higher BMIs had even shorter life spans. Plus, obesity sets you up for an increased risk of health complications including high blood pressure, high cholesterol, type 2 diabetes, heart disease, stroke, gallbladder disease, osteoarthritis, sleep apnea, and serious COVID-19 disease.
Diet and Lifestyle Changes
First, make daily changes to how you eat and live. “We always encourage patients to try to diet and exercise first because that is the most safe method for weight loss,” says Dr. Ali. Be sure to speak with your doctor and potentially a registered dietitian-nutritionist before embarking on any diet or exercise plan, to ensure you are making changes that are safe and appropriate for you. Diet There are a variety of diets that may help support your efforts to lose and maintain weight loss, but 2020–2025 Dietary Guidelines for Americans (PDF) say that whichever you choose should do the following, whether you are trying to lose or maintain weight:
Emphasize nutrient-dense foods and beverages, which include fruits, vegetables, whole grains, and fat-free or low-fat milk and milk products, fortified soy beverages, lean meats, poultry, fish, beans, eggs, and nuts and seeds (with a greater emphasis on beans and peas, soy products, nuts, and seeds if you are vegetarian).Minimize your intake of saturated fats, trans fats, cholesterol, sodium, and added sugar.Derive less than 10 percent of calories per day from added sugars from age 2.Derive less than 10 percent of calories per day from saturated fats from age 2.Stay within your daily calorie needs.
Calorie needs vary by age, sex, height, weight, activity level, and whether you are trying to lose, gain, or maintain weight. For adult women the recommended range is 1,600 to 2,400 calories per day, and for adult men the range is 2,000 to 3,000 calories per day. For children ages 2 to 8 the range is from 1,000 to 2,000, and for older children and adolescents the range is 1,400 to 3,200. The dietary guidelines include a chart where you can find the calorie target that suits you best.Your primary care doctor and a registered dietitian-nutritionist, among other specialists, can help provide more individualized advice, especially in cases where you are looking to manage other underlying health conditions. Exercise According to federal physical activity guidelines for Americans (PDF), aim for the following level of physical activity, even if you are not trying to lose weight: For adults:
Do at least 150 minutes to 300 minutes a week of moderate-intensity exercise (like walking briskly, line dancing, yoga, playing doubles tennis, or raking leaves).Alternatively, do 75 minutes to 150 minutes a week of vigorous-intensity aerobic physical activity, such as jogging, running, cycling more than 10 miles an hour, or high-intensity interval training (HIIT).Older adults with chronic conditions should do as much activity as their health allows.
For youth:
Preschool-age children should remain active throughout the day and be encouraged to play or otherwise move their bodies.Children ages 6 to 7 should do an hour or more of moderate to vigorous physical activity daily.
“In the National Weight Control Registry over 90 percent of those who maintained long-term weight loss engaged in at least 60 minutes per day of physical activity,” Dr. Kane notes. Meanwhile, if you are at the beginning of your weight loss journey and have a lot of weight to lose, be patient with yourself, he advises. Patients with obesity beginning an exercise program must think of the long term. In the end they will want to be engaged in regular physical activity, but it takes time to build up strength, endurance, and flexibility. Be persistent, but safe.”
Medication Options
If diet and exercise alone aren’t enough to get you to a healthy weight, and your BMI is 30 or more (or your BMI is 27 to 29.9 and you have a complication such as type 2 diabetes or high blood pressure), your doctor may prescribe medication to add to your regimen, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Among the more common medications listed by the NIDDK that are approved by the U.S. Food and Drug Administration (FDA) for long-term use are:
orlistat (Xenical), which is available at a lower dose without a prescription under the name Alliphentermine-topiramate (Qsymia)naltrexone-bupropion (Contrave)liraglutide (Saxenda), an injectable that is also FDA approved at a lower dose to treat type 2 diabetes under the name Victozasemaglutide (Wegovy), an injectable that is also FDA approved to treat type 2 diabetessetmelanotide (IMCIVREE), an injectable that is also FDA approved for children with Bardet-Biedl syndrome who are 6 or older
Perez-Colon notes that these medications are approved for children:
orlistat (Xenical)phentermine-topiramate (Qsymia)phentermineliraglutide (Saxenda), an injectable that is also FDA approved at a lower dose to treat type 2 diabetes under the name Victoza
She says that the type 2 diabetes medication metformin (Glucophage) has sometimes been prescribed for weight loss in adolescents, along with other interventions, but it is not FDA approved for that use because studies are mixed. A review that followed overweight or obese people who were given metformin found that adults experienced a small amount of weight loss over time. “[Some] obesity medications at higher doses can cause more rapid weight loss, but one typically sees weight regain without continuing them indefinitely,” Kane cautions. Mounjaro (tirzepatide) is a newly FDA-approved medication used to improve blood sugar control in adults with type 2 diabetes. It may soon also get approval to treat obesity, according to October 2022 reporting by Reuters. Weight loss medications can be pricey, and they’re not always covered by health insurance, which makes them inaccessible to many people.
Mental Health Options for Behavioral Change
Research suggests there’s a two-way relationship between obesity and mental health. A previous analysis of studies determined that obesity increases the risk of depression, especially among Americans; and also that depression is a risk factor for developing obesity. The CDC reports that 43 percent of adults with depression were obese, compared with 33 percent of adults without depression, as of 2010. This greater risk of obesity was especially strong in white women. Rates of obesity by depression status did not differ among men across groups, nor did they differ in Black and Mexican American women and men. “The good news is that weight loss efforts, with the help of a mental health professional, can help one cope and develop strategies to reverse or at least diminish the negative feelings,” says Dominick Gadaleta, MD, a bariatric surgeon in Bay Shore, New York. Also notable is people who have a history of childhood trauma may be at an increased risk for health conditions such as obesity, research suggests. If you are seeking professional counseling related to your weight or your perception of it, speak with your doctor for a referral, or do a key phrase search for “obesity" and “weight-loss” in the American Psychological Association’s Psychologist Locator to find a therapist in your area.
Surgery Options
For people with severe obesity who have not been able to lose the weight they desire to through diet, exercise, and medication, weight loss surgery may be an option. Ali says that patients who come to him for surgery are typically 100 pounds overweight. The American Society for Metabolic and Bariatric Surgery (ASMBS) says other qualifications for bariatric surgery include having a BMI of 40 or greater (even if you are less than 100 pounds overweight); or having a BMI of 35 to 39.39 along with obesity-related complications such as type 2 diabetes, high blood pressure, heart disease, osteoarthritis, nonalcoholic fatty liver disease, sleep apnea, or other breathing problems. Candidates usually undergo thorough psychological counseling and a medically supervised diet before surgery, according to the organization, per the ASMBS. Weight loss surgery leaves a patient with a stomach that can hold far less food than before, and most options also restrict the body’s ability to absorb calories and nutrients. The procedures are typically minimally invasive laparoscopic surgeries, according to the ASMBS. Ali says the most common surgery types are: Laparoscopic Sleeve Gastrectomy (Sleeve) About 80 percent of the stomach is surgically removed from the body, leaving a banana-shaped pouch, as the ASMBS describes it. The amount of food that can be consumed is drastically reduced by the procedure, and changes happen in gut hormones that suppress hunger, make you feel full when you eat, and reduce high blood sugar. People lose around half of their excess weight on average within the three- to five-year time frame, and maintain that level of loss in the long term, according to the association. Other less common bariatric surgeries include biliopancreatic diversion with duodenal switch (BPD-DS) gastric bypass and laparoscopic adjustable gastric band (lap band), says Ali. The ASMBS describes how they work. Roux-en-Y Gastric Bypass (Gastric Bypass) As the ASMBS explains, in this procedure, the stomach is divided into two sections by a surgeon and only one small part of it holds the food you eat. The lower part of the small intestine is attached directly to that small stomach pouch, so that food can bypass most of the stomach and the upper part of the small intestine. As a result, the body absorbs fewer calories. Then the bypassed section is connected further down to the lower part of the small intestine — still attached to the main part of your stomach — so digestive juices can move from your stomach and the first part of your small intestine into the lower part of your small intestine. Rerouting the food stream alters gut hormones that suppress hunger, make you feel full when you eat, and reduce high blood glucose (sugar). People lose on average 60 to 80 percent of their excess weight, and maintain a loss of at least 50 percent in the long term, according to ASMBS. Intragastric Balloon Therapy (IGB) For people who have a BMI of 30 to 39.9, with or without other chronic health conditions, this less-invasive procedure is an option. According to the FDA, a surgeon places one or more inflatable balloons into the stomach endoscopically or through a capsule that is attached to a catheter and swallowed. The balloons are then filled with gas or saline and then sealed to take up space in the stomach and delay the exit of food from the stomach into the small intestine. The balloons are removed at a later date. According to the Mayo Clinic, typical weight loss is about 7 to 15 percent of your body weight during the six months after balloon placement, and total excess weight loss is in the 30 to 47 percent range. After the surgery, people must stick to a high-protein, very low carbohydrate diet with small portions per meal, says Ali. The regimen helps to prevent dumping syndrome, in which overly rapid movement of food into the small intestine can cause abdominal cramping, nausea, vomiting, and low blood sugar, the Cleveland Clinic explains. “As long as you are getting the amount of calories your body needs each day and not eating in excess of that, then you can maintain the weight loss,” says Ali. Learn More About Weight Loss Surgery
Complementary and Integrative Approaches
Several complementary and integrative approaches can be used along with conventional medical interventions to help with obesity treatment. “There is a role for a traditional physician, and there’s also a role for an integrative health practitioner,” said Laura Purdy, MD, a board-certified family medicine physician who operates a virtual clinic. “It is so important to have good communication between all of the people on your healthcare team, so that you can have the very best transparent, patient-centered care possible,” she added. These approaches include, per the National Center for Complementary and Integrative Health:
Dietary supplements (though research on their efficacy is limited)Mind-body approaches such as yoga and meditation
While many of these practices are considered low-risk, Dr. Purdy still recommends talking to a physician before choosing an integrative approach to add to your treatment. With supplements in particular, work with your healthcare team to ensure what you’re interested in taking doesn’t interfere or negatively react with any medications you may be taking. Learn More About Obesity Treatment For children specifically, Pérez-Colón discourages drinking sweetened beverages such as juice and soda, eating late at night, eating large portions, or frequently having second portions. Not eating enough fruits and vegetables is also associated with childhood obesity. Furthermore, she cautions against children not getting enough sleep or enough exercise and having too much screen time on phones, computers, or TV. “ “Nowadays, children and adolescents prefer to play with electronics instead of going outside to play. They’re sitting there for a long time, which predisposes them to obesity.” The CDC has tips to help children maintain a healthy weight. While preventing obesity in children usually comes down to lifestyle changes, which should include all family members, Pérez-Colón says in rare cases a genetic component or other diseases may be the reason, particularly if the weight gain begins when the child is younger than 5.
Complications of Obesity in Adults
For instance, in adults, excessive body fat is linked to the following conditions, according to the CDC:
High blood pressure (hypertension)High cholesterol (dyslipidemia)Type 2 diabetesHeart diseaseStrokeGallbladder diseaseOsteoarthritisSleep apnea and other breathing problemsMany types of cancersSerious COVID-19 diseaseMental health disordersDifficulty with physical functioningBody painLow quality of lifeAll causes of death
Complications of Obesity in Children
Perez-Colon says, “Child obesity is a risk factor by itself to develop adult obesity and the associated comorbidities.” Insulin resistance, which can set the stage for diabetes and may be diagnosed as early as the onset of puberty, is just one example she gives, supported by an article published in July 2016 in Current Diabetes Reports. According to the CDC, children with obesity can also experience:
HypertensionHigh cholesterolType 2 diabetesBone and joint problemsSleep apneaAsthmaType 2 diabetesHeart diseaseStrokeFatty liver diseaseGallstonesAcid refluxBullyingDepressionPoor self-esteem
Learn More About Obesity Complications In women, obesity is associated with anovulation (lack of ovulation, or release of eggs from the ovaries), according to the U.S. Department of Health and Human Services (HHS). It can also prevent fertility treatments such as IVF from working. PCOS, a common cause of infertility, is linked to obesity. In men, obesity is associated with low semen quality, decreased libido, and erectile dysfunction, according to a review of literature published in the Central European Journal of Urology in 2015. For obese women who do conceive, HHS cautions that obesity raises the risk of such pregnancy complications as:
Gestational diabetesHigh blood pressureMiscarriagePreeclampsia (a serious complication of late pregnancy)Abnormal labor, often leading to cesarean section
Fetuses of overweight or obese women have a higher risk of:
PrematurityStillbirthCongenital anomalies (birth defects)Macrosomia (being overly large)Childhood obesity
Losing weight before pregnancy and minimizing weight gain during pregnancy can help to lower these risks. Learn More About How BMI Affects Fertility and Conception
The prevalence was 40 percent among adults ages 20 to 39, 45 percent among those 40 to 59, and 43 percent among adults age 60 and over.Men (43 percent) and women (42 percent) had similar obesity rates.Obesity affected 18.5 percent of youth ages 2 to 19 in 2016.Obesity created $161 billion excess healthcare costs and $66 billion in lost workplace productivity in the United States.
Learn More About Obesity in America The socioeconomic and environmental factors that can affect access to healthy, affordable food or safe places to move around are known as social determinants of health, as the HHS explained in Healthy People 2030. The CDC notes that “communities with poor social determinants of health such as unstable housing, low income, unsafe neighborhoods, or substandard education” can significantly impact the health of individuals and families downstream. Pérez-Colón, who is Hispanic, says that her own practice experience has taught her that her Black and Hispanic patients are less likely to have access to safe places and green spaces to get exercise. Additionally, cultural norms about body size vary by population, she says. She says when she was growing up, her older relatives believed that gaining weight was a sign of good health in a child, and she now works to dispel that notion in the families of the children she treats.
Black Americans and Obesity
From 2017 through March 2020, Black adults had the highest prevalence of obesity compared with all other racial and Hispanic-origin groups, at about 50 percent. In the same period, about 25 percent of Black children ages 2 to 19 were obese, compared with about 17 percent of white children.
Hispanic Americans and Obesity
From 2017 to 2020, about 46 percent of Hispanic adults were obese, compared with about 41 percent of white adults. Obesity prevalence among Hispanic children in the same years was about 26 percent.
Asian Americans and Pacific Islanders and Obesity
Data from 2017 to March 2020 suggests Asian adults had the lowest prevalence of obesity among all racial and Hispanic-origin groups, at about 16 percent. Likewise, Asian children ages 2 to 19 had the lowest prevalence of obesity of all groups, at 9 percent. But these statistics may be skewed. As previously mentioned, Asians and Asian Americans may have increased health risks at a lower BMI. Joslin’s BMI calculator for this group lowers the floor for overweight BMI to 23 and the floor for obesity to 27.
Native Americans and Obesity
American Indian and Alaska Native adults are more than 50 percent more likely to be obese than white adults, according to the HHS. Twenty-one percent of American Indian and Alaska Native high school students reported being obese, compared with 13 percent of white high schoolers in 2019, according to data from the National High School Youth Risk Behavior Survey. The OMA is a professional organization for those who treat obesity, and claims more than 2,500 members. The news section, though intended for clinicians, contains a wealth of consumer-friendly articles about the treatment of obesity and healthy living, such as, ”Benefits Of Fiber-Rich Foods For Weight Loss” and “How Does Your Brain Affect Your Weight Loss Journey?” If you are seeking a specialist in your area, try the directory of clinicians. American Society for Metabolic and Bariatric Surgery (ASMBS) The ASMBS is a professional organization for surgeons, physicians, and other healthcare professionals involved in the treatment of obesity and related metabolic disorders. It has a robust patient education section that is a must-read if you are considering weight loss surgery or seeking information about life after surgery, with topics such as “Making Choices About Surgery,” and “Medical Tourism.” You can search their directory for a surgeon who performs weight loss or minimally invasive procedures in your area.
Favorite Online Support Networks
Obesity Action Coalition (OAC) This nonprofit is focused on creating a world where those who are affected by obesity can access safe and effective treatments and be treated without bias, regardless of size or weight. The OAC has more than 75,000 members, who connect through a community discussion forum and work together to change healthcare policies affecting people with obesity.
Favorite Resources for Diet Advice and Info
Food Data Central If you want to know the caloric, fat, carbohydrate, and nutrient content of just about anything edible — in a variety of serving sizes — drop this name into the search window for a massive database run by the U.S. Department of Agriculture (USDA). Whether you are counting calories or carbs, having this bookmarked in your browser can be handy. U.S. World and News Report: Best Diets Each year the magazine ranks the most popular diets according to a variety of criteria, including weight loss, commercial plans, plant-based, and many more. This is a great resource if you are searching for the best diet to fit your health goals, or want to know how the newest diet trend measures up. Find out how popular diets ranked in this year’s list in our article. Healthy for Good: American Heart Association The top organization focused on heart health hosts Healthy for Good, which calls itself a movement for creating “lasting change in your health and your life, one small step at a time.” If you sign up for free it gives you access to a microsite with shareable tips, recipes and cooking videos, a YouTube home workout playlist and science-based blog articles.
Favorite Diet and Fitness Apps
MyPlate The USDA has a simple app to help you reach your healthy eating goals across a broad mix of food groups. Once you set your goals, it sends daily notifications to remind you; and if you tap on a reminder for a food group, a recipe suggestion will pop up. Download it in the Apple Store or GooglePlay. Learn more about MyPlate in our comprehensive article. MyFitnessPal This popular app — 1.1 million downloads in the Apple Store and a rating average of 4.7 stars — is about far more than logging your fitness activities. It also includes an interactive food diary to help you keep track of how many calories you are taking in and burning off each day. When you choose an activity or food, the calories attached are automatically added to your daily tracker. The free version does have obtrusive ads. If you upgrade, the monthly plan is $9.99. Download it in the Apple Store or GooglePlay. Further, obesity can decrease your lung capacity and affect the functioning of your immune system, which in turn compromises your ability to recover from COVID-19, says the agency. As mentioned, Hispanic and Black adults have higher obesity rates than their white peers. They are also more likely to have worse outcomes from COVID-19, with higher hospitalization and death rates. Learn More About How COVID-19 Can Affect People With Obesity Additional reporting by Ingrid Strauch.
