Home Insider The Body Mass Index – A Pointer to Good Health?

The Body Mass Index – A Pointer to Good Health?

The Body Mass Index has become a health marker that supposedly indicates a person’s health, disease risk and fitness level. It is used by medical insurance companies and organizations that need to estimate the healthcare costs of their employees, not to mention doctors, health specialists and of course, the common man who finds himself putting on weight and is a bit worried how much weight he can afford to put on without jeopardizing his health.

While the poor struggle to procure two meals a day, the elite grapple with the reality of expanding waistlines, trying to rein in the weight gain and somehow gorge on sumptuous rich food and yet stay slim. This is not just to look good any more, it is more about staying healthy as health risks loom dangerously for those considered overweight. The overweight and obesity indicator in most cases, is inevitably, the easy to calculate BMI.

What is BMI .

The BMI is a numerical value derived from the weight and height of a person. It attempts to quantify the muscle, fat and bone mass of the person and based on the value derived, classify him or her as obese, normal or underweight. Also called the Quetelet Index, it was developed by Adolphe Quetelet a Belgian statistician and mathematician, in 1832, while analyzing human physical attributes and human growth. His conclusion was that “body weight increases as the square of height”. This concept was given the name of Body Mass Index by Ancel Keys in 1972, and has since, become popular globally in medical circles and day-to-day life as a measure of fitness and health. The BMI is a good measure of thickness or thinness of the human body and a helpful tool for medical professionals to gauge a patient’s health and the risk of diseases like hypertension, diabetes, coronary heart disease, arthritis etc occurring. The higher the patient’s BMI, the greater the risk of one or more of these diseases, by and large. It is calculated by taking a person’s weight in kilograms divided by the square of his height in meters.

The ideal BMI falls between 18.5 and 24.9, which is considered the normal range of weight for the person’s height. A BMI level less than 18.5 is indicative of being underweight and a level between 25-29.9 puts the person in the overweight range, and any level above 30 means the person falls in the obese category. The BMI for children is calculated differently depending upon their age and sex. Overweight and obese people are at risk of developing diseases that can be limiting and incapacitating, and therefore need to lose weight and target a lower BMI to be fit. Thus it serves as a broad indicator or health marker that cannot be taken literally and exclusively, and does require other checks and tests to get a detailed certificate of health.

Is BMI a true indicator of health?

A tall, well built 70-year old woman, felt some discomfort in her chest and, being a doctor, was convinced that this might be the first indication of lifelong, coronary heart disease. Her body mass index was over 30 (putting her in the obese segment) and her physical appearance, made people think of her as highly overweight, if not obese. A series of laboratory and diagnostic tests including the treadmill stress test revealed that she had a healthy heart of a 30-year old, and was perfectly healthy in all respects. This is just one out of thousands of cases of perfectly healthy people getting alarmed when they see their body mass index above normal, permissible limits and being termed obese or at least, overweight. In truth the BMI, as it is popularly known, is merely a basic, general indicator and cannot be taken seriously enough to consider one’s life in danger or even at risk of a serious, life-threatening disease or alternatively, ignore other indicators just because the BMI is within normal limits.

The BMI was meant to serve as a simple method of classifying an average sedentary, inactive population with a very average body composition. The easiest to use, it has been the first step test for good health as the outcome of individual weight levels. It is neither time consuming nor expensive and doesn’t require any exposure to machines, devices or laboratory tests.

It is perhaps the ease of use that transformed the BMI into a fad and an accepted norm, a topic of conversation and discussion and a value converted and checked by one and all, sending many on a crash diet to lose weight and others whose levels were in the normal range, went on an eating binge, which caused more problems, instead of solving them.

The BMI concept is fraught with problems and inaccuracies. It was devised by a mathematician who had no background in medicine, health or fitness, and based his formula on empirical evidence gathered from a section of the young population. It was created for a section of the male population but now is used for women as well and the same formula is applied for both genders. Over the years, a series of limitations of the BMI concept have come to the fore. These include:

  • The BMI overestimates the amount of body fat in people with a muscular build and in the case of athletes.
  •  It underestimates the body fat in older people and those who have less muscle or lost muscle as part of the ageing process.
  •  It ignores variations in physical characteristics of individuals. Thus two people with entirely different physiques may have the same BMI but one may be at risk and the other may not.
  •  The index cannot differentiate between body mass and muscle mass, leading to erroneous figures.
  •  It does not take into consideration whether the body has more fat, muscle or water; nor does it look at where the fat is stored. Latest research about health risks points towards fat around the waist being more dangerous than in other sections of the body.
  •  Data collected for research at Mayo Clinic, Rochester revealed interesting facts about the BMI index in 40 studies carried out on 250, 000 people suffering from heart disease. It was found that the obese patients were at a higher risk of death, while the overweight ones had fewer heart issues than those who had a normal BMI. Many call it ‘the obesity paradox’. This can be attributed to the muscularly built people having a BMI level that put them in the overweight category even though they were physically more fit than the ones with normal levels.
  •  BMI provides an incomplete representation of health since it is not able to correlate other vital health markers like cholesterol and triglyceride levels.
  •  The one size fits all approach in the BMI is not right since weight, height and physique vary with race, age and country depending on the eating habits and climatic conditions of the place.

Alternatives to BMI

The BMI has been sufficiently criticized but not completely discarded and remains in use, though cautiously so. Medical experts feel that the BMI should either be combined with other tests and indicators. In the recent past, the waist circumference has been seen as a better indicator of health risks. This is because the latest research reveals that belly fat, called visceral fat, is more dangerous than fat that is found under the skin in the rest of the body. Visceral fat is harmful since it is deposited deep in between the muscles and organs like the liver, and prevents the body from balancing its energy needs through the release of certain hormones. Hence, ‘apple shaped’ bodies seem to be more at risk of developing health problems than ‘pear shaped’ ones. Weight around the hips is considered potentially less dangerous. Experts believe that waist circumference for men should be less than 40 inches and less than 35 inches for women.

Other indicators being used include the BAI-the Body Adiposity Index, which is the body fat calculator, the waist-to-hip ratio and hydrostatic weighing. The bottom line of course, is pursuing a healthy lifestyle with sufficient physical activity, healthy food choices while avoiding overeating, and regular medical checkups to nip an illness almost as soon as any symptoms appear.

The final word on BMI

The BMI was created as a measure of fatness and became an indicator of fitness instead. In the midst of availability of plenty, we look at the ideal weight, the ideal diet, the perfect lifestyle but wish to get away with a few excesses. We seek reaffirmation that we are on the right track with numbers that seem to indicate our fitness levels and encourage us to continue on our pursuit of eating for pleasure, while health takes a back seat. The secret to health and fitness, looking great and feeling good, radiating peace and calm and feeling the same within, comes from balance -the ability to weigh the good and bad, moderate the excesses and seek a middle path so that the end result is towards the positive and a precursor of a long, healthy life.