Table of ContentsView AllTable of ContentsWhat Is Obesity?TypesWays of Measuring
Table of ContentsView All
View All
Table of Contents
What Is Obesity?
Types
Ways of Measuring
Although the term “morbid obesity” was used in the past to describe severe obesity, healthcare providers now categorize obesity as being either Class 1, Class 2, or Class 3. With each advancing class, not only does the risk of death and disease increase but so too does the cost of healthcare.
In the United States, around two of every five adults meet the definition of obesity, the condition of which costs the American healthcare system over $170 billion annually.
This article explains what obesity is, how each class of obesity is defined, and how the definition can vary in different groups. It also describes the impact of obesity on your health and other ways that obesity is diagnosed in adults.
By way of example, if you weigh 200 pounds (91 kg) and are 6 feet tall (1.5 meters), your BMI would be calculated as follows:91 kg ÷ (1.5 x 1.5 mg) = 40.4 BMI.
Although BMI has certain limitations, it remains the strongest tool for assessing your risk of disease due to obesity, also known as obesity-associated morbidities (OAMs). These include:
The risk of these and other OAMs increases with the degree (severity) of obesity.
Obesity and Depression: Is There a Connection?
Types of Obesity
In the past, obesity was classified as being either “regular” obesity or “morbid” obesity (“morbid” meaning “having symptoms of a disease”). The latter term, first coined during the 1960s, has since been abandoned, in part because any level of obesity is associated with an increased risk of disease, whether symptomatic orasymptomatic.
According to an analysis of the ongoing National Health and Nutrition Examination Survey (NHANES), around 20% of adults in the United States meet the definition of Class 1 obesity, while roughly 9% and 6% have Class 2 and Class 3 obesity, respectively.
Each of these classifications has a direct impact not only on a person’s health but also on their risk of death.
How Obesity Affects Your Blood Pressure (And What You Can Do About It)
Obesity and Morbidity
The OAMs included an array of cardiovascular, metabolic, digestive, respiratory, neurological, musculoskeletal, and infectious diseases.
Not surprisingly, the risk of OAMs was higher among adults with Class 3 obesity than those with Class 1 or Class 2 obesity. Moreover, when compared to people of healthy weight, the risk of having multiple morbidities (like heart disease and diabetes) increased with each obesity class.
Obesity and Mortality
Numerous studies have shown that the rate of mortality (death) also increases with the severity of obesity. This includes disease-specific deaths and “all-cause mortality” (death from all causes).
Other Ways of Measuring Obesity
Body mass index (BMI) has long been the standard for diagnosing obesity. However, as a tool, BMI has its limitations.
Among them, the interpretation of BMIs has long been based on the rate of OAMs in populations that are disproportionately White. In some cases, a BMI considered “unhealthy” in a White population may be regarded as “healthy” in Black populations where these OAMs are less commonly seen.
At the same time, being very short or very tall can lead to misinterpretation of BMI. For instance, a person with a very small frame can proportionately carry more body fat but still have a healthy BMI—a phenomenon referred to as “skinny fat”). On the other hand, a person with a very tall (or large) frame may have fairly low body fat but still fall within the “overweight” or “obese” category.
To this end, there are different ways of diagnosing obesity that may provide more insightful information than a BMI alone:
Body Fat Percentage
Body fat percentage (BF%)is the ratio of the weight of your body fat to your total body weight. This can be estimated using tools like skinfold calipers, hydrostatic weighing,bioelectrical impedance, air-displacementplethysmography, and3D body scans.
By calculating the BF%, a highly trained athlete may be overweight according to their BMI but still be in optimal health. Likewise, a person with a healthy weight based on their BMI may have an unhealthy amount of body fat and be at risk of weight-related diseases.
According to the American Council on Exercise, body fat percentages over 32% for females and 25% for males are diagnostic of obesity.
The problem with BF% is that methods like skinfold calipers and hydrostatic weighing are not all that accurate, while tools like plethysmography and 3D body scans are expensive and not readily available.
Central Obesity
Also known as abdominal obesity,central obesityis the excessive accumulation of fat surrounding your abdominal organs (also known asvisceral fat).
Central obesity is one of the criteria fordiagnosing metabolic syndromeand is strongly associated with an increased risk of heart disease in people with BMIs over 30.
There are several methods used to diagnose central obesity, including:
Summary
Obesity is defined as a body mass index (BMI) of 30 or greater.
There are different classes of obesity: Class 1 is a BMI of between 30 and 34.9, Class 2 is a BMI between 35 and 39.9, and Class 3 is a BMI of 40 or greater. The higher the class, the greater the risk of obesity-related illness and death.
A BMI is not always an accurate measurement of obesity for very short people, very tall people, or people of different races or ethnicities. Other methods may be useful in diagnosing obesity, including measuring body fat percentage (BF%) and central (abdominal) obesity.
14 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.Lin X, Li H.Obesity: epidemiology, pathophysiology, and therapeutics.Front Endocrinol (Lausanne).2021;12:706978. doi:10.3389/fendo.2021.706978Centers for Disease Control and Prevention.Adult obesity facts.Centers for Disease Control and Prevention.Assessing your weight.Abdelaal M, le Roux CW, Cocherty NG.Morbidity and mortality associated with obesity.Ann Transl Med.2017 Apr;5(7):161. doi:10.21037/atm.2017.03.107Celio AC, Pories WJ.A history of bariatric surgery.Surg Clin N Am. 2016;96:655–667. doi:10.1016/j.suc.2016.03.001Sun JY, Huang WJ, Hua Y, et al.Trends in general and abdominal obesity in US adults: Evidence from the National Health and Nutrition Examination Survey (2001–2018).Front Public Health.2022;10:925293. doi:10.3389/fpubh.2022.925293Kivimaki M, Strandberg T, Pentti J, et al.Body-mass index and risk of obesity-related complex multimorbidity: an observational multicohort.Lancet Diabetes Endocrinol.2022;10(4):253-263. doi:10.1016/S2213-8587(22)00033-XPonce-Garcia I, Simarro-Rueda M, Carbayo-Herencia JA, et al.Prognostic value of obesity on both overall mortality and cardiovascular disease in the general population.PLoS One.2015;10(5):e0127369. doi:10.1371/journal.pone.0127369Kitahara CM, Flint AJ, de Gonzalez AB, et al.Association between Class III obesity (BMI of 40–59 kg/m2) and mortality: a pooled analysis of 20 prospective studies.PLoS Med.2014 Jul;11(7):e1001673. doi:10.1371/journal.pmed.1001673Okobi OE, Beeko PKA, Nikravesh E, el al.Trends in obesity-related mortality and racial disparities.Cureus.2023 Jul;15(7):e41432. doi:10.7759/cureus.41432Sperrin M, Marshall AD, Higgins V, Renehan AG, Buchan IE.Body mass index relates weight to height differently in women and older adults: serial cross-sectional surveys in England (1992–2011).J Public Health (Oxf).2016 Sep;38(3):607–613. doi:10.1093/pubmed/fdv067American Council on Exercise.Demystifying body fat percentages: a healthy range explained.Rao G, Powell-Wiley TM, Ancheta I, et al.Identification of obesity and cardiovascular risk in ethnically and racially diverse populations: a scientific statement from the American Heart Association.Circulation. 2015;132(5):457-472. doi:10.1161/CIR.0000000000000223Fang H, Berg E, Cheng X, Shen W.How to best assess abdominal obesity.Curr Opin Clin Nutr Metab Care. 2018;21(5):360-365. doi:10.1097/MCO.0000000000000485
14 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.Lin X, Li H.Obesity: epidemiology, pathophysiology, and therapeutics.Front Endocrinol (Lausanne).2021;12:706978. doi:10.3389/fendo.2021.706978Centers for Disease Control and Prevention.Adult obesity facts.Centers for Disease Control and Prevention.Assessing your weight.Abdelaal M, le Roux CW, Cocherty NG.Morbidity and mortality associated with obesity.Ann Transl Med.2017 Apr;5(7):161. doi:10.21037/atm.2017.03.107Celio AC, Pories WJ.A history of bariatric surgery.Surg Clin N Am. 2016;96:655–667. doi:10.1016/j.suc.2016.03.001Sun JY, Huang WJ, Hua Y, et al.Trends in general and abdominal obesity in US adults: Evidence from the National Health and Nutrition Examination Survey (2001–2018).Front Public Health.2022;10:925293. doi:10.3389/fpubh.2022.925293Kivimaki M, Strandberg T, Pentti J, et al.Body-mass index and risk of obesity-related complex multimorbidity: an observational multicohort.Lancet Diabetes Endocrinol.2022;10(4):253-263. doi:10.1016/S2213-8587(22)00033-XPonce-Garcia I, Simarro-Rueda M, Carbayo-Herencia JA, et al.Prognostic value of obesity on both overall mortality and cardiovascular disease in the general population.PLoS One.2015;10(5):e0127369. doi:10.1371/journal.pone.0127369Kitahara CM, Flint AJ, de Gonzalez AB, et al.Association between Class III obesity (BMI of 40–59 kg/m2) and mortality: a pooled analysis of 20 prospective studies.PLoS Med.2014 Jul;11(7):e1001673. doi:10.1371/journal.pmed.1001673Okobi OE, Beeko PKA, Nikravesh E, el al.Trends in obesity-related mortality and racial disparities.Cureus.2023 Jul;15(7):e41432. doi:10.7759/cureus.41432Sperrin M, Marshall AD, Higgins V, Renehan AG, Buchan IE.Body mass index relates weight to height differently in women and older adults: serial cross-sectional surveys in England (1992–2011).J Public Health (Oxf).2016 Sep;38(3):607–613. doi:10.1093/pubmed/fdv067American Council on Exercise.Demystifying body fat percentages: a healthy range explained.Rao G, Powell-Wiley TM, Ancheta I, et al.Identification of obesity and cardiovascular risk in ethnically and racially diverse populations: a scientific statement from the American Heart Association.Circulation. 2015;132(5):457-472. doi:10.1161/CIR.0000000000000223Fang H, Berg E, Cheng X, Shen W.How to best assess abdominal obesity.Curr Opin Clin Nutr Metab Care. 2018;21(5):360-365. doi:10.1097/MCO.0000000000000485
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.
Lin X, Li H.Obesity: epidemiology, pathophysiology, and therapeutics.Front Endocrinol (Lausanne).2021;12:706978. doi:10.3389/fendo.2021.706978Centers for Disease Control and Prevention.Adult obesity facts.Centers for Disease Control and Prevention.Assessing your weight.Abdelaal M, le Roux CW, Cocherty NG.Morbidity and mortality associated with obesity.Ann Transl Med.2017 Apr;5(7):161. doi:10.21037/atm.2017.03.107Celio AC, Pories WJ.A history of bariatric surgery.Surg Clin N Am. 2016;96:655–667. doi:10.1016/j.suc.2016.03.001Sun JY, Huang WJ, Hua Y, et al.Trends in general and abdominal obesity in US adults: Evidence from the National Health and Nutrition Examination Survey (2001–2018).Front Public Health.2022;10:925293. doi:10.3389/fpubh.2022.925293Kivimaki M, Strandberg T, Pentti J, et al.Body-mass index and risk of obesity-related complex multimorbidity: an observational multicohort.Lancet Diabetes Endocrinol.2022;10(4):253-263. doi:10.1016/S2213-8587(22)00033-XPonce-Garcia I, Simarro-Rueda M, Carbayo-Herencia JA, et al.Prognostic value of obesity on both overall mortality and cardiovascular disease in the general population.PLoS One.2015;10(5):e0127369. doi:10.1371/journal.pone.0127369Kitahara CM, Flint AJ, de Gonzalez AB, et al.Association between Class III obesity (BMI of 40–59 kg/m2) and mortality: a pooled analysis of 20 prospective studies.PLoS Med.2014 Jul;11(7):e1001673. doi:10.1371/journal.pmed.1001673Okobi OE, Beeko PKA, Nikravesh E, el al.Trends in obesity-related mortality and racial disparities.Cureus.2023 Jul;15(7):e41432. doi:10.7759/cureus.41432Sperrin M, Marshall AD, Higgins V, Renehan AG, Buchan IE.Body mass index relates weight to height differently in women and older adults: serial cross-sectional surveys in England (1992–2011).J Public Health (Oxf).2016 Sep;38(3):607–613. doi:10.1093/pubmed/fdv067American Council on Exercise.Demystifying body fat percentages: a healthy range explained.Rao G, Powell-Wiley TM, Ancheta I, et al.Identification of obesity and cardiovascular risk in ethnically and racially diverse populations: a scientific statement from the American Heart Association.Circulation. 2015;132(5):457-472. doi:10.1161/CIR.0000000000000223Fang H, Berg E, Cheng X, Shen W.How to best assess abdominal obesity.Curr Opin Clin Nutr Metab Care. 2018;21(5):360-365. doi:10.1097/MCO.0000000000000485
Lin X, Li H.Obesity: epidemiology, pathophysiology, and therapeutics.Front Endocrinol (Lausanne).2021;12:706978. doi:10.3389/fendo.2021.706978
Centers for Disease Control and Prevention.Adult obesity facts.
Centers for Disease Control and Prevention.Assessing your weight.
Abdelaal M, le Roux CW, Cocherty NG.Morbidity and mortality associated with obesity.Ann Transl Med.2017 Apr;5(7):161. doi:10.21037/atm.2017.03.107
Celio AC, Pories WJ.A history of bariatric surgery.Surg Clin N Am. 2016;96:655–667. doi:10.1016/j.suc.2016.03.001
Sun JY, Huang WJ, Hua Y, et al.Trends in general and abdominal obesity in US adults: Evidence from the National Health and Nutrition Examination Survey (2001–2018).Front Public Health.2022;10:925293. doi:10.3389/fpubh.2022.925293
Kivimaki M, Strandberg T, Pentti J, et al.Body-mass index and risk of obesity-related complex multimorbidity: an observational multicohort.Lancet Diabetes Endocrinol.2022;10(4):253-263. doi:10.1016/S2213-8587(22)00033-X
Ponce-Garcia I, Simarro-Rueda M, Carbayo-Herencia JA, et al.Prognostic value of obesity on both overall mortality and cardiovascular disease in the general population.PLoS One.2015;10(5):e0127369. doi:10.1371/journal.pone.0127369
Kitahara CM, Flint AJ, de Gonzalez AB, et al.Association between Class III obesity (BMI of 40–59 kg/m2) and mortality: a pooled analysis of 20 prospective studies.PLoS Med.2014 Jul;11(7):e1001673. doi:10.1371/journal.pmed.1001673
Okobi OE, Beeko PKA, Nikravesh E, el al.Trends in obesity-related mortality and racial disparities.Cureus.2023 Jul;15(7):e41432. doi:10.7759/cureus.41432
Sperrin M, Marshall AD, Higgins V, Renehan AG, Buchan IE.Body mass index relates weight to height differently in women and older adults: serial cross-sectional surveys in England (1992–2011).J Public Health (Oxf).2016 Sep;38(3):607–613. doi:10.1093/pubmed/fdv067
American Council on Exercise.Demystifying body fat percentages: a healthy range explained.
Rao G, Powell-Wiley TM, Ancheta I, et al.Identification of obesity and cardiovascular risk in ethnically and racially diverse populations: a scientific statement from the American Heart Association.Circulation. 2015;132(5):457-472. doi:10.1161/CIR.0000000000000223
Fang H, Berg E, Cheng X, Shen W.How to best assess abdominal obesity.Curr Opin Clin Nutr Metab Care. 2018;21(5):360-365. doi:10.1097/MCO.0000000000000485
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts.Cookies SettingsAccept All Cookies
By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts.
Cookies SettingsAccept All Cookies
