Table of ContentsView AllTable of ContentsClasses of ObesityRisksBMIOther Influencing FactorsTreatmentNext in Obesity GuideObesity Symptoms
Table of ContentsView All
View All
Table of Contents
Classes of Obesity
Risks
BMI
Other Influencing Factors
Treatment
Next in Obesity Guide
Overweight andobesitymeans weighing more than what is thought to be healthy for a person of that height.Body mass index (BMI), which estimates your level of body fat based on your height and weight, is often used to determine if a person has overweight or obesity.
A BMI of 30 to 34.9 is considered obesity class 1, 35 to 39.9 is obesity class 2, and over 40 is obesity class 3.Having obesity is considered a risk factor for a number of health conditions, such as heart disease and type 2 diabetes. The risk for health conditions goes up on a continuum as BMI goes up.
What Are the Obesity Classes?
BMI exists on a continuum, but for clinical and research purposes, BMI measures are divided into categories indicating underweight, healthy weight, overweight, and obesity. Obesity is further divided into the following three classes:
Some clinicians and researchers further divide Class 3 into two more categories:
Obesity classes do not assess an individual’s health but look at overall risks generally associated with those ranges. As a general trend, as BMI increases, so does the likelihood of health problems. These classes may also be used for purposes such as population research and as part of eligibility criteria for treatments such asbariatric surgery.
Risks Associated With Obesity
Compared to people within the BMI category labeled as healthy, people with obesity have an increased risk of developing health conditions such as:
Obesity is one risk factor for these conditions. The more risk factors a person has, the more likely the person is to develop the health problem.
For example, your risk of developing heart disease increases if you have obesity and other risk factors such as:
What Is Body Mass Index (BMI)?
Body mass index (BMI) is a measure of body fat based on a person’s height and weight.On an individual basis, BMI may be used as a screening tool but cannot be used to determine the health of that individual. A healthcare provider needs to perform appropriate health assessments to evaluate an individual person’s health and risks.
How to Calculate Your BMI
Consulting aBMI index chartor using a BMI calculating tool can make this easier.
The CDC offers aBMI calculator for people 20 years old and olderand a BMI calculator for people age 2 through 19.
Beyond Obesity Classes: Other Influencing Factors
BMI has limitations for its accuracy as a tool todetermine a “healthy” weight. For example:
Other tools may also be used to estimate the potential risk for health conditions. These may include:
Many factors influence both the development of obesity and the risk of developing health conditions associated with obesity. These may include:
What Is Considered Underweight?ABMIof less than 18.5 is considered in the underweight range.A BMI of 18.5 to 24.9 is considered in the healthy weight range.A BMI of 25.0 to 29.9 is considered in theoverweightrange.A BMI of 30.0 or higher is considered in theobesityrange.
What Is Considered Underweight?
ABMIof less than 18.5 is considered in the underweight range.A BMI of 18.5 to 24.9 is considered in the healthy weight range.A BMI of 25.0 to 29.9 is considered in theoverweightrange.A BMI of 30.0 or higher is considered in theobesityrange.
Treatment to Go Down an Obesity Class
Achieving the weight or BMIthat is optimal for you involves fostering an overall health-promoting lifestyle.To do this, it’s important to:
More Intensive Weight Loss Treatments
In some cases, particularly for those who fall under the classification of class 3 obesity, weight loss can be difficult to achieve and maintain with lifestyle changes alone.
Your healthcare provider may suggesttreatmentssuch as:
A Word From Verywell
—KARINA TOLENTINO, RD, MEDICAL EXPERT BOARD
Summary
A BMI of 30 or over is consideredhaving obesity. Obesity is divided into three classes, with increasing BMIs. Risk of health conditions increases as BMI goes up. Obesity can increase the risk of developing health conditions such as type 2 diabetes, heart disease, and stroke.
If you have obesity, losing even 5% to 10% of your body weight can reduce the risk of obesity-related health conditions.
If you feel weight loss might be beneficial to you, talk to a healthcare provider. They can help you make a plan that emphasizes healthy ways to achieve and sustain a body weight that is right for you and adopting lifestyle habits that promote health, such as nutritious eating and physical activity.
13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.MedlinePlus.Health risks of obesity.Government of Canada.Canadian guidelines for body weight classification in adults - quick reference tool for professionals.World Health Organization.Obesity: health consequences of being overweight.Harvard T.H. Chan School of Public Health.Body fat.Lorenzo AD.New obesity classification criteria as a tool for bariatric surgery indication.WJG. 2016;22(2):681. doi:10.3748/wjg.v22.i2.681Centers For Disease Control and Prevention.Steps for losing weight.Messier SP, Gill ME, Mihalko SL, et al.Clinical, health‐related quality of life, and gait differences among obesity classes in adults with knee osteoarthritis.Arthritis Care & Research. 2024:acr.25265. doi:10.1002/acr.25265NIH. National Heart, Lung, and Blood Institute.Calculate your body mass index.National Health Service.Body mass index.World Obesity Federation.Obesity classification.Australian Government Department of Health and Aged Care.Body mass index (BMI) and waist measurement.National Health Service.Obesity.National Institute of Diabetes and Digestive and Kidney Diseases.Treatment for overweight & obesity.
13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.MedlinePlus.Health risks of obesity.Government of Canada.Canadian guidelines for body weight classification in adults - quick reference tool for professionals.World Health Organization.Obesity: health consequences of being overweight.Harvard T.H. Chan School of Public Health.Body fat.Lorenzo AD.New obesity classification criteria as a tool for bariatric surgery indication.WJG. 2016;22(2):681. doi:10.3748/wjg.v22.i2.681Centers For Disease Control and Prevention.Steps for losing weight.Messier SP, Gill ME, Mihalko SL, et al.Clinical, health‐related quality of life, and gait differences among obesity classes in adults with knee osteoarthritis.Arthritis Care & Research. 2024:acr.25265. doi:10.1002/acr.25265NIH. National Heart, Lung, and Blood Institute.Calculate your body mass index.National Health Service.Body mass index.World Obesity Federation.Obesity classification.Australian Government Department of Health and Aged Care.Body mass index (BMI) and waist measurement.National Health Service.Obesity.National Institute of Diabetes and Digestive and Kidney Diseases.Treatment for overweight & obesity.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
MedlinePlus.Health risks of obesity.Government of Canada.Canadian guidelines for body weight classification in adults - quick reference tool for professionals.World Health Organization.Obesity: health consequences of being overweight.Harvard T.H. Chan School of Public Health.Body fat.Lorenzo AD.New obesity classification criteria as a tool for bariatric surgery indication.WJG. 2016;22(2):681. doi:10.3748/wjg.v22.i2.681Centers For Disease Control and Prevention.Steps for losing weight.Messier SP, Gill ME, Mihalko SL, et al.Clinical, health‐related quality of life, and gait differences among obesity classes in adults with knee osteoarthritis.Arthritis Care & Research. 2024:acr.25265. doi:10.1002/acr.25265NIH. National Heart, Lung, and Blood Institute.Calculate your body mass index.National Health Service.Body mass index.World Obesity Federation.Obesity classification.Australian Government Department of Health and Aged Care.Body mass index (BMI) and waist measurement.National Health Service.Obesity.National Institute of Diabetes and Digestive and Kidney Diseases.Treatment for overweight & obesity.
MedlinePlus.Health risks of obesity.
Government of Canada.Canadian guidelines for body weight classification in adults - quick reference tool for professionals.
World Health Organization.Obesity: health consequences of being overweight.
Harvard T.H. Chan School of Public Health.Body fat.
Lorenzo AD.New obesity classification criteria as a tool for bariatric surgery indication.WJG. 2016;22(2):681. doi:10.3748/wjg.v22.i2.681
Centers For Disease Control and Prevention.Steps for losing weight.
Messier SP, Gill ME, Mihalko SL, et al.Clinical, health‐related quality of life, and gait differences among obesity classes in adults with knee osteoarthritis.Arthritis Care & Research. 2024:acr.25265. doi:10.1002/acr.25265
NIH. National Heart, Lung, and Blood Institute.Calculate your body mass index.
National Health Service.Body mass index.
World Obesity Federation.Obesity classification.
Australian Government Department of Health and Aged Care.Body mass index (BMI) and waist measurement.
National Health Service.Obesity.
National Institute of Diabetes and Digestive and Kidney Diseases.Treatment for overweight & obesity.
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