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The body mass index (BMI) or Quetelet index is a value derived from the mass (weight) and height of an individual. The BMI is defined as the body mass divided by the square of the body height, and is universally expressed in units of kg/m2, resulting from mass in kilograms and height in metres. The BMI may also be determined using a table〔e.g. the (Body Mass Index Table ) from the National Institutes of Health's NHLBI.〕 or chart which displays BMI as a function of mass and height using contour lines or colors for different BMI categories, and may use two different units of measurement.〔For example, in the UK where people often know their weight in stone and height in feet and inches, – see ()〕 The BMI is an attempt to quantify the amount of tissue mass (muscle, fat, and bone) in an individual, and then categorize that person as ''underweight'', ''normal weight'', ''overweight'', or ''obese'' based on that value. However, there is some debate about where on the BMI scale the dividing lines between categories should be placed. Commonly accepted BMI ranges are underweight: under 18.5, normal weight: 18.5 to 25, overweight: 25 to 30, obese: over 30. ==Usage== The index was devised by Adolphe Quetelet from 1830 to 1850 during which time he developed what he called "social physics". The modern term "body mass index" (BMI) for the ratio of human body weight to squared height owes its popularity to a paper published in the July 1972 edition of the ''Journal of Chronic Diseases'' by Ancel Keys. This found the BMI to be the best proxy for body fat percentage among ratios of human body weight and height. The interest in an index that measures body fat came with increasing obesity in prosperous Western societies. BMI was explicitly cited by Keys as appropriate for ''population'' studies and inappropriate for individual evaluation. Nevertheless, due to its simplicity, it has come to be widely used for preliminary diagnosis.〔(【引用サイトリンク】url=http://www.nhlbi.nih.gov/health/educational/lose_wt/risk.htm )〕 Additional metrics, such as waist circumference, can be more useful.〔(【引用サイトリンク】url=http://www.nhs.uk/Conditions/Obesity/Pages/Introduction.aspx )〕 If pounds and inches are used, a conversion factor of 703 (kg/m2)/(lb/in2) must be applied. When the term BMI is used informally, the units are usually omitted. : BMI ranges from underweight to obese and is commonly employed among children and adults to predict health outcomes. The BMI trait is influenced by both genetic and non-genetic factors, and it provides a paradigm to understand and estimate the risk factors for health problems.〔Fareed M, Afzal M. (2014) Evidence of inbreeding depression on height, weight, and body mass index: A population-based child cohort study. Am J Hum Biol. 26:784–795. PMID 25130378〕 BMI provides a simple numeric measure of a person's ''thickness'' or ''thinness'', allowing health professionals to discuss weight problems more objectively with their patients. BMI was designed to be used as a simple means of classifying average sedentary (physically inactive) populations, with an average body composition. For these individuals, the current value recommendations are as follow: a BMI from 18.5 up to 25 may indicate optimal weight, a BMI lower than 18.5 suggests the person is underweight, a number from 25 up to 30 may indicate the person is overweight, and a number from 30 upwards suggests the person is obese.〔〔 Many (e.g. gymnasts, basketball and soccer players) but not all (e.g. football linemen) athletes have a high muscle to fat ratio and may have a BMI that is misleadingly high relative to their body fat percentage.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Body mass index」の詳細全文を読む スポンサード リンク
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