Body Mass Index
Original Editor - Lucinda hampton
Top Contributors - Lucinda hampton, Kim Jackson and Naomi O'Reilly
Introduction[edit | edit source]
Body mass index, or BMI, is used to determine a person’s healthy weight range for their height. It is useful to consider BMI alongside waist circumference, as waist measurement helps to assess risk by measuring the amount of central fat. BMI is a useful measurement for most people over 18 years old. However it is only an estimate and not taking into account age, ethnicity, gender and body composition.[1] At the cellular level, an increase or decrease in BMI can have a significant effect on physiology. Research has shown associations with BMI to insulin resistant states, inflammatory states, and cognition.[2]
Definition and Classification[edit | edit source]
Body mass index or BMI is a statistical index using a person's weight and height to provide an estimate of body fat in males and females of any age. It is calculated by taking a person's weight, in kilograms, divided by their height, in meters squared, or BMI = weight (in kg)/ height^2 (in m^2). The number generated from this equation is then the individual's BMI number.
While BMI can provide a useful estimate of healthy weight, individual variations do exist. BMI alone is insufficient as the sole means of classifying a person as obese or malnourished. For example, elite athletes and body-builders, an elevated BMI does not directly correlate to their health status due to their increased muscle mass and weight falsely increasing their BMI.[3]
The BMI number and classifications are listed below, these classifications for BMI are in use by the NIH and the World Health Organization (WHO)[3]
- White, Hispanic and Black individuals
- Severely underweight - BMI less than 16.5kg/m^2
- Underweight - BMI under 18.5 kg/m^2
- Normal weight - BMI greater than or equal to 18.5 to 24.9 kg/m^2
- Overweight – BMI greater than or equal to 25 to 29.9 kg/m^2
- Obesity – BMI greater than or equal to 30 kg/m^2
Asian and South Asian Population:
- Overweight - BMI between 23 and 24.9 kg/m^2;
- Obesity - BMI greater than 25 kg/m^2[3]
Related Tests[edit | edit source]
When individuals are identified as an abnormal weight, certain testing should be done.
- BMI >30 kg/m2: Lipid panel, thyroid function tests, and diabetes screening should be performed. Patients should be advised on a healthy diet and exercise.
- BMI< 18 kg/m2: Tests for thyroid function, comprehensive metabolic panel, psychiatric screening for an eating disorder, and evaluation of malabsorption conditions should be conducted. If weight loss was rapid and unintentional, a test for cancer should also be considered.[2]
BMI and Physiotherapy[edit | edit source]
The growing obesity epidemic and increasing population with high BMI numbers are significant concerns. Physiotherapists play an emerging role in addressing obesity, providing exercise guidelines and support for individuals with high BMI. In cases of eating disorders, BMI is used to determine appropriate exercise guidelines. See Anorexia Nervosa
References[edit | edit source]
- ↑ Heart Foundation BMI Available: https://www.heartfoundation.org.au/bmi-calculator (accessed 13.8.2021)
- ↑ 2.0 2.1 Zierle-Ghosh A, Jan A. Physiology, Body Mass Index. [Updated 2020 Jul 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan Available:https://www.ncbi.nlm.nih.gov/books/NBK535456/(accessed 13.8.2021)
- ↑ 3.0 3.1 3.2 Weir CB, Jan A. BMI Classification Percentile And Cut Off Points. In: StatPearls. StatPearls Publishing, Treasure Island (FL); 2023. PMID: 31082114 .Available:https://europepmc.org/article/nbk/nbk541070 (accessed 14 June 2024)
