Body Mass Index BMI Validity and Reliability The Quetelet Index for calculating

Body mass index bmi validity and reliability the

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Body Mass Index (BMI) Validity and Reliability The Quetelet Index for calculating BMI (body weight (kilograms) divided by height 2 (meters)) was developed by Keys et al., in 1972 (Nuttall, 2015). Nuttall (2015), stated that squaring the height reduces the contribution of leg length to the equation and normalizes body mass distribution at each level of height, reducing the effect of a variance in height in the relationship of weight to height. This was an important change because most of body fat is in the trunk. According to Nuttall (2015), the BMI is a poor representation of a person’s percent of body fat. BMI, though an index of obesity, does not differentiate between body lean mass and body fat mass, meaning that a person can have a high BMI but still have a very low fat mass and vice versa. The poor correlation between percent of body fat mass and BMI was recently shown in the NHANES III (National Health and Nutrition Examination Survey) database in which bioelectrical impedance was used to estimate body fat (Nuttall, 2015). Among individuals with a BMI of 25 kg/m2, the percentage of body fat in men was between 14% and 35%, while that of women varied between 26% and 43%. According to Nuttall (2015), these results then motivated the National Institute of Health (NIH) to suggest new criterion to define obesity, based on percent of body fat. Another limitation of the BMI is that it does not capture body fat location information, even though this is an important variable in assessing the metabolic and mortality consequences of excessive fat accumulation (Nuttall, 2015). Fat accumulation in the upper part of the body is
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associated with an increased risk for coronary heart disease, diabetes, gallstones and gout, as opposed to fat accumulation in the lower part of the body, reducing the prevalence of these complications as well as mortality rates in individuals who accumulate excessive fat in the lower segments of their bodies (Nuttall, 2015).
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