First what is Body Mass Index? Like other measurement tools, such as weight, BMI is simply another method to help assess your level of fitness. While statistics show that the BMI is a great predictor of general health factors, it does in fact, have limitations.
Effectiveness of BMI
1. It is the best way to determine a healthy weight for an individual.
It is able to be applied to both sexes, young and old. The calculation of BMI can be used to quickly asses an individual weight classification. BMI also offers better accuracy on estimating the degree of body fat. It also provides a range of scale for ‘normal’ weight measurement. This allows classification and compensation of different body types and shapes.
2. BMI provides quick calculation for classification of an individual.
The simple formulae for calculating BMI provides faster classification to individuals who are also physically inactive and has average body composition. It indicates to them what is considered a healthy, normal weight range of BMI for their height. In addition, many studies have shown that, with the range and classification of BMI, has a possible link of developing obesity related diseases as well as premature death.
3. BMI allows easy reference and indication to an individual regarding being overweight.
BMI is the product of height and weight. With the availability to refer to BMI charts, it is useful in comparing with others of the same age, gender and race. Moreover, the BMI chart can be a source of national indication to a country for the state of health of its citizens. This is because BMI can be calculated with reference to their age according to different age groups as it has different ranges for being overweight, underweight or normal weight.
Limitations of BMI
The accuracy and theory behind BMI system has long been argued. However, the duality of the BMI is that, whilst being an easy to use, general calculation, it is limited in how accurate and pertinent the data obtained from it can be.
1. BMI does not take into account the lean body mass of a person.
Our bodies are made up of bones, muscle, organs and fat. Lean body mass refers to the active mass which is made up of muscle, bones, and other body organs such as the heart, liver and kidneys. The BMI makes no accounting for relative differences in bone mass, muscle mass and fat, and the differing weights of each. In other words, the BMI is unable to differentiate 30 kilograms of muscles from 30 kilograms of fats.
2. Overestimating the body fat in athletes and others who have a muscular build.
Someone with an extraordinarily large amount of muscle mass, such as a bodybuilder, may seem to be at risk (due to the heavy weight) when in fact the amount of fats in their body have been overestimated. The top-rated bodybuilders and the professional athletes who tip the scales at 250 to 300 pounds and stand anywhere from 5'6" to 5'11", are often classified as obese by the BMI standards, showing the flaws in the system.
3. Ethnic and population differences
For example, in comparison, Asian populations may require a lower BMI to describe health risk, while Pacific populations, specifically Hawaiian, may require a higher threshold to indicate that an individual is at risk. This variation can be explained by body type. Because ethnicity has been shown to require adjustments to the levels of concern for the BMI, care must be taken when comparing different population groups.
Furthermore, the percentage of body fat and fat distribution vary between different population groups. Apart from age and sex, ethnicity and physical activity level affect the percentage of body fat. People living near the North Pole generally have more body fat than people living in more moderate temperature zones. The ethnic differences in fat proportion and corresponding risk levels might also stem from differences in relative body type or frame size.
Nevertheless, on a population level, BMI is considered to be an appropriate measure. The required data are easier to obtain on a national level and the BMI is easily calculated on the basis of standard measures. The evaluation of BMI is efficient, requiring minimal training, and results are available in a short period of time.
However, when evaluating the BMI, several characteristics of an individual need to be known. An individual's age, gender, ethnicity, and level of fitness must be considered when using BMI to determine health risk. Also, the significance of the BMI may affected by medical conditions. Thus, BMI should be used in combination with other measures of health, such as the waist to hip ratio, to provide a better judgment of a person’s health. And it is important to note that such judgments should be made with the help of a doctor or other health care professional.
References:
http://www.naturalphysiques.com/tools.php?itemid=31
http://www.topendsports.com/testing/tests/BMI.htm
http://www.foxnews.com/story/0,2933,149807,00.html
http://www.halls.md/ideal-weight/percentile.htm
http://www.emusclemag.com/content.php?cat=10&id=215
http://theopavlidis.com/HealthIssues/bmi_0.htm
http://calorielab.com/news/2009/07/09/body-mass-index-flaws/
http://www.metabolismjournal.com/article/S0026-0495(07)00407-6/abstract
http://www.euphix.org/object_document/o4852n27195.html
http://www.naturalphysiques.com/tools.php?itemid=31
http://www.topendsports.com/testing/tests/BMI.htm
http://www.foxnews.com/story/0,2933,149807,00.html
http://www.halls.md/ideal-weight/percentile.htm
http://www.emusclemag.com/content.php?cat=10&id=215
http://theopavlidis.com/HealthIssues/bmi_0.htm
http://calorielab.com/news/2009/07/09/body-mass-index-flaws/
http://exercise.about.com/od/exerciseworkouts/g/leanbodymass.htm
http://www.faqs.org/nutrition/Ar-Bu/Body-Mass-Index.html
http://spidersport.com/lean-body-mass_en.php
http://www.nhlbi.nih.gov/health/public/heart/obesity/lose_wt/risk.htm
