Body mass index

From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history

Body Mass Index or BMI is a number calculated using height and weight, and sometimes gender or age (in children) that aims to measure whether someone's weight is within a healthy weight range, or if they are underweight, overweight or obese.[1][2] BMI values are used as a screening tool to aid diagnosis of certain illnesses, for example the presence or severity of anorexia nervosa, and metabolic syndrome, and to assess risk factors and demographic associations for many illnesses, and for some medical procedures.[1]

BMI chart[edit | edit source]

BMI ranges in adults[edit | edit source]

The United States CDC uses these ranges for adults. For children and adolescents, alternative ranges are used.[3][1]

Under 18.5 Underweight
18.5 - under 25 Healthy weight
25.0 - under 30 Overweight
30.0 - under 35 Obesity class 1
35.0 - under 40 Obesity class 2
40.0 or higher Obesity class 3 (severe obesity)

The CDC regards a Body Mass Index of 30 or higher in adults as obesity.[2]

Criticisms[edit | edit source]

BMI evolved from an attempt to develop better health risk assessments for the United States health insurance industry than the height/weight tables used in the early 1900s, and were largely based on values for White adult men.[4] In the 1990s, the World Health Organization adopted BMI as a medical measure and published ranges. Today BMI is widely regarded as as measure of "fat-ness" and has been found to contribute to both social stigma and bias or stigma from doctors and clinicans.[4]

Key criticisms include:

  • the EPIC study of over 350,000 adults in Europe (aged 25 to 70) found that increased mortality was associated with a BMI of less than 21 or over 30, which is significantly different from the BMI ranges in use, men with a BMI of 26.5 had the lowest risk, similar results were found in the larger NIH–American Association of Retired Persons study
  • BMI is a relatively poor measure of fat-ness, and does not take into account waist circumference or muscle mass, it may assess some people with a high proportion of fat as in a healthy range and some with a healthy proportion as overweight or even obese
  • Older adults typically have reduced muscle mass, and higher amounts of fat, which means BMI may be too high for them[5]
  • Mortality is often associated with a higher BMI, but a higher mortality in "wasting diseases" such as tuberculosis is associated with a lower BMI
  • Risk of developing diabetes, metabolic syndrome and coronary heart disease has been found to be more closely associated with accumulated fat stores in the upper body than overall[4]

Alternatives[edit | edit source]

A number of alternative measures exist that may be more accurate or provide additional information when screening for health risks:

  • waist circumference
  • abdominal/hip circumference ratio
  • skin-fold thickness measurements in different areas of the body
  • percentage body fat can be measured by underwater weighing, air displacement and density determination (using a Bod Pod), a bioelectrical impedance analyzer, and a determination of the isotopically labeled water mass
  • a DEXA x-ray scan can estimate fat accumulation around organs[4]

Subgroup[edit | edit source]

ME/CFS[edit | edit source]

Body mass index is not considered a risk factor or an indicator for disease progression or for severity in ME/CFS - people with moderate ME/CFS typically have a higher BMI than those with severe ME/CFS.[6] Studies looking at the small minority who have recovered from ME/CFS have not found BMI or any other factors predictive of recovery, except for short illness duration and milder illness.[7][8]

Most people with ME/CFS have a BMI in the healthy range, although obesity is relatively common in United States patients with ME/CFS.[9]

Cost and availability[edit | edit source]

BMI is extremely easy to measure and calculate, and can be assessed by patients at home.

See also[edit | edit source]

Calculators[edit | edit source]

Learn more[edit | edit source]

References[edit | edit source]

  1. 1.0 1.1 1.2 "Healthy Weight, Nutrition, and Physical Activity Section | About Adult BMI". Centers for Disease Control and Prevention. June 11, 2021. Retrieved January 11, 2022.
  2. 2.0 2.1 "Defining Adult Overweight and Obesity". Centers for Disease Control and Prevention. June 7, 2021. Retrieved January 11, 2022.
  3. "Body Mass Index Table 1". National Heart, Lung and Blood Institute. Retrieved January 12, 2022.
  4. 4.0 4.1 4.2 4.3 Nuttall, Frank Q. (2015). "Body Mass Index: Obesity, BMI, and Health: A Critical Review". Nutrition Today. 50 (3): 117–128. doi:10.1097/NT.0000000000000092. ISSN 0029-666X.
  5. "BMI calculator | Check your BMI". National Health Service. October 28, 2021. Retrieved January 12, 2022.
  6. Nacul, Luis Carlos; Mudie, Kathleen; Kingdon, Caroline C.; Clark, Taane G.; Lacerda, Eliana Mattos (2018). "Hand Grip Strength as a Clinical Biomarker for ME/CFS and Disease Severity". Frontiers in Neurology. 9: 992. doi:10.3389/fneur.2018.00992. ISSN 1664-2295.
  7. Schur, Ellen A.; Noonan, Carolyn; Smith, Wayne R.; Goldberg, Jack; Buchwald, Dedra (January 1, 2007). "Body Mass Index and Fatigue Severity in Chronic Fatigue Syndrome". Journal of Chronic Fatigue Syndrome. 14 (1): 69–77. doi:10.1300/J092v14n01_07. ISSN 1057-3321.
  8. Carruthers, BM; van de Sande, MI; De Meirleir, KL; Klimas, NG; Broderick, G; Mitchell, T; Staines, D; Powles, ACP; Speight, N; Vallings, R; Bateman, L; Bell, DS; Carlo-Stella, N; Chia, J; Darragh, A; Gerken, A; Jo, D; Lewis, DP; Light, AR; Light, KC; Marshall-Gradisnik, S; McLaren-Howard, J; Mena, I; Miwa, K; Murovska, M; Stevens, SR (2012), Myalgic encephalomyelitis: Adult & Paediatric: International Consensus Primer for Medical Practitioners (PDF), ISBN 978-0-9739335-3-6
  9. U.S. ME/CFS Clinician Coalition (July 2020). "Diagnosing and Treating Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)" (PDF) (2 ed.). p. 4.