Let us first see what BMI is, its significance and current relevance. Thereafter also study other different indices to measure health of a person.
(1)BMI:
Body Mass Index (BMI) is a person's weight in kilograms (or pounds) divided by the square of height in meters (or feet).
For example if body weight of a person is 95 kg and height is 5 feet and 9 inch equal to 1.75 meter.
BMI= 95/1.75×1.75
=95/3.06=31.04
BMI is 31.04
Category:Obese
BMI is 31.1 indicating person weight is in the Obesity category for adults . BMI is a screening measure and is not intended to diagnose disease or illness.
BMI screens for weight categories that may lead to health problems, but it does not diagnose the body fatness or health of an individual.BMI is an inexpensive and easy screening method for weight category:underweight, healthy weight, overweight, obesity and very high obesity.
The 5 categories of BMI:
Normal Weight Ranges: Body Mass Index (BMI)
(i)Underweight: BMI is less than 18.5.
(ii) Normal weight: BMI is 18.5 to 24.9.
(iii) Overweight: BMI is 25 to 29.9.
(iv) Obese: BMI is 30 or more.
(v) Very obese :35 or more
The main flaw: It's an indirect measure of body fat that doesn't take into account important details about age, sex, bone structure, and fat distribution, one study in the International Journal of Obesity explained. Again, it's just deal with two numbers: weight divided by height squared.
Flaw meaning imperfection or weakness and especially one that detracts from the whole or hinders effectiveness .
Cardiovascular disease and Osteoarthritis are two health risks people face with a BMI above 25.
Factors such as age, sex, ethnicity, and muscle mass can influence the relationship between BMI and body fat. Also, BMI does not distinguish between excess fat, muscle, or bone mass, nor does it provide any indication of the distribution of fat among individuals. It does not differentiate between fat and lean body mass. For example, an athlete or bodybuilder with a large amount of muscle mass could very easily fall into the overweight or obese or very Obese categories based on their BMI.It is an Indirect and imperfect measurement- it cannot measure between body fat and lean body mass. It is not as accurate with the elderly persons as it is with children and adults.BMI does not account for muscle mass and only takes weight into account. If someone has high muscle mass they will have a high BMI but they are not necessarily overweight they just have high muscle mass and low-fat mass.For example Athletes, Gymnastics, Wrestler
.
BMI can be inaccurate:
More and more research shows that there are biological and genetic differences in the relationship between weight, muscle mass and disease risk among different groups of people. BMI does not account for that. Certain genetic factors can affect BMI accuracy because of their effect on weight distribution and muscle mass.Thus BMI is inaccurate and misleading one.
Body Mass Index' biggest flaw is that it does not take into account the person's body fat versus muscle (lean tissue) content. Muscle weighs more than fat (Muscle is denser, a cubic inch of muscle weighs more than a cubic inch of fat).
BMI may not be accurate for everyone.Whereas someone with a lower weight and a much higher body fat to lean mass ratio could fall under the normal to healthy range. Plus, BMI doesn't account for gender, age, or ethnicity, so it may not be an equally valid test for all populations.
BMI doesn't account for body composition, which means it misses the difference between muscle mass and fat. or overweight based on their BMI alone.
You can have a high BMI even if you have very little body fat, especially if you're male and very muscular.Your muscle mass makes up most of your weight. It doesn't take into account your waist circumference, which can be a good measure of your risk for certain diseases, including heart disease and type II diabetes mellitus.Your muscle mass makes up most of your weight.
(2)Waist-to-height ratio (WHtR).:
An alternative index of health to BMI is the
Waist-to-height ratio (WHtR).
The cousin of the BMI, waist-to-height ratio compares you guessed it waist circumference to height, rather than overall weight to height squared.
The guideline says a healthy waist to height ratio is 0.4 to 0.49, indicating no increased health risks. A ratio of 0.5 to 0.59 puts people at increased risk of health issues, while 0.6 or more puts them at the highest risk of health problems.
Waist to height ratio is an indicator of your risks for obesity, heart disease, diabetes, stroke, and hypertension. It is obtained by dividing waist size by height. Men and women should keep their waist circumference, no more than half their height.
Waist to height ratio should not be confused with the 'Waist to Hip Ratio' which is used to measure body fat distribution. Both, however, can be used to screen possible health problems.
Waist-to-height ratio (WHtR)
WHtR is more accurate than BMI because it takes central fat into consideration. Central fat is important because it collects around the organs in your midsection and has been closely linked to conditions such as heart disease.
Waist to height ratio is an indicator of your risks for obesity, heart disease, diabetes, stroke, and hypertension. It is obtained by dividing waist size by height. Men and women should keep their waist circumference, no more than half their height.
Waist to height ratio should not be confused with the 'Waist to Hip Ratio' which is used to measure body fat distribution. Both, however, can be used to screen possible health problems. Waist circumference has a direct correlation with the risk of developing heart disease, because it measures the critical levels of fat accumulated between internal organs and the torso, that is, visceral fat. Visceral fat is directly connected to strokes and heart disease. Greater the waist circumference, the higher the morbidity and mortality from heart disease, diabetes, stroke and hypertension.
The waist-height ratio indicator is equally valid for children and adults, irrespective of age, although the parameters for waist circumference, height and waist-height ratio could vary between races and ethnicities.
(3) Waist-to-hip ratio (WHR) is one of several measurements your doctor can use to see if excess weight is putting your health at risk.
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Waist-to-hip ratio chart:
Risk Women. Men
low. 0.80 or low 0.95 or low
moderate 0.81-0.85. 0.96-1.0
high 0.86 or high 1.0 or high
Higher Waist circumference has a direct correlation with the risk of developing heart disease, because it measures the critical levels of fat accumulated between internal organs and the torso, that is, visceral fat. Visceral fat is directly connected to strokes and heart disease. Greater the waist circumference, the higher the morbidity and mortality from heart disease, diabetes, stroke and hypertension.
The waist-height ratio indicator is equally valid for children and adults,irrespective of age, although the parameters for waist circumference, height and waist-height ratio could vary between races and ethnicities.
Though it has been used for decades as the go-to measurement for health based on body size, it has been widely criticized for its oversimplification of what being healthy really means. In fact, many claim BMI is outdated and inaccurate and shouldn't be used in medical and fitness settings.
(4) Relative Fat Mass Index, or RFM:
Now scientists think they've come up with a new and improved alternative: say hello to the relative fat mass index, or RFM.
RFM has replaced BMI.
relative fat mass index
BMI not a good health indicator.Relative Fat Mass (RFM):It is a simple formula for the estimation of overweight or obesity in humans that requires only a calculation based on a ratio of height and waist measurements. High body fat is associated with increased risks of poor health and early mortality.
Relative Fat Mass (RFM) is a simple formula for the estimation of overweight or obesity in humans that requires only a calculation based on a ratio of height and waist measurements. High body fat is associated with increased risks of poor health and early mortality.
Relative fat mass(RFM) is more accurate than BMI:
Researchers at the Cedars-Sinai Diabetes and Obesity Research Institute developed the relative fat mass index, a measurement designed to be more accurate than BMI at predicting health risks.
Good fat mass:
Men and women need different amounts of fat. For a man, 2–5% fat is essential, 2–24% fat is considered healthy, and more than 25% classifies as obesity. For a woman, 10–13% fat is essential, 10–31% fat is healthy, and more than 32% classifies as obesity.
Conclusion:
Current Relevance of BMI:
As a single measure, BMI is clearly not a perfect measure of health. But it's still a useful starting point for important conditions that become more likely when a person is overweight or obese.
Body mass index, or BMI, is currently the most widely used method for assessing whether someone is overweight or underweight.
“BMI isn't an accurate representation of health because it takes the ratio of height and weight and doesn't factor into account the type of weight a person may have, such as muscle compared to fat,” explains Kearn
BMI which is based on the height and weight of a person, is an inaccurate measure of body fat content and does not take into account muscle mass, bone density, overall body composition, and racial and sex differences, say researchers from the Perelman School of Medicine, University of Pennsylvania.
BMI isn't necessarily an Indicator of your overall health.Your muscle mass makes up most of your weight.BMI doesn't account for body composition, which means it misses the difference between muscle mass and fat. or overweight based on their BMI alone.A reliable way to determine whether a person has too much body fat is to calculate the ratio of their weight to their height squared.
Doctors still use BMI because Body Mass Index Is a Good Gauge of Body Fat.
The most basic definition of overweight and obesity is having too much body fat-so much so that it “presents a risk to health.” However other indices waist to height ratio;waist to hip ratio and relative fat mass mentioned here must also be taken in to consideration for the measurement of health of a person.
Information compiled by: Dr. Bhairavsinh Raol
