Wanted

An Asian measure of obesity

 
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By Sarita Bahl
Published: Wednesday 15 September 2004

-- Although obesity is today a global pandemic, research on the disease in India is still nascent. This worries experts: nearly 15-30 per cent of the country's urban population and four to eight per cent of the rural population is either overweight or obese, with children forming 16-18 per cent in this group. It is a rising trend, experts say; the rate at which urban Indians are turning overweight or obese already equals that found in Western European cities. An added concern is the parameters by which an Indian -- indeed an Asian -- can be declared overweight or obese.

Twenty years ago, researchers in Europe and the us defined the normal limits of bmi, or body mass index, a measure of obesity. (Expressed in kilogramme per metre square, kg/m2, it is the ratio of a person's weight and height that takes into consideration the total composition of fat, muscle, bone and tissues in the human body.) Surveying around 80,000 Caucasians, researchers correlated the bmi of each person to mortality rates. This led to the first-ever definition of obesity: those with bmi between 25-29.9 kg/m2 were classified as overweight and those with bmi above 30 kg/m2 were classified obese. The International Task Force on Obesity and the World Health Organization (who) accepts these limits -- they are now universally applicable. But these limits are precisely what researchers in Asia are today questioning. They are based on the Caucasian body. How can they be applicable to Asians, whose bodies are different?
One such researcher Five to six years ago, Anoop Misra, a professor at the department of internal medicine, All India Institute of Medical Sciences, New Delhi, became intrigued by a phenomenon: obesity is one of the strongest risk factors for diabetes, but Misra noted that whereas diabetics among his patients were on the rise, these very people couldn't be categorised as obese. Misra began researching this puzzling fact. Officially, not more than five to 10 per cent of Indians had a bmi more than 30 kg/m2. So how was the leap in diabetes cases to be explained?

Universally, bmi is measured by two rules: body fat as a standard and comparing the bmi against it; and by comparing bmi against diseases. Misra found that, in Indians, at lower bmi the body fat was high. "Suppose at a bmi of 25-26 kg/m2, 10 per cent of Caucasians have diabetes, then Indians achieve that 10 per cent at a bmi of 22 kg/m2 itself," says Misra. In other words, Indians become classifiable as overweight or obese at a lower bmi. According to him, this warrants the bmi limit for which Indians should be labeled as overweight to be less than 25, thereby redefining the global limit (see table: New definition). "It is not the question of diabetes alone," Misra says.

New definition
WHO is yet to make this redefinition mandatory
Definition Existing BMI criteria globally (kg/m2) New BMI criteria for Asian Pacific population (kg/m2)
Normal 18.5-25 18.5-23
Overweight 25-29.9 23-27.5
Obese > 30 > 27.5
"It is the question of lipid disorders, heart disorders and heart diseases. A lot of these diseases are noticed in the Asian population at a lower bmi."
Why are Indians different? Genetic makeup, feels Misra. Indians in any case have less muscle content and more fat content when compared to Caucasians. And what if diet and lifestyle is taken into consideration, as overwhelming evidence shows it must? "It is a saga of multiple adversity," says Misra. As diets become increasingly laden with saturated fats, more carbohydrates and less fibre -- a diet that goes with a more "westernised" lifestyle, meaning one that includes eating more meat, eating out regularly and eating more 'fast' or 'junk' food -- Indians gain fat really fast, without bloating up. Another factor that contributes to lower muscle mass among Indians, speculates Misra, is under-nutrition among pregnant mothers, which results in lower protein content in their children, and so lower muscle content. When the body is starved of proteins, it may begin to store up fat, much as a misguided miser hoards up coins; the fat gets stored in body spaces that need to be filled up by muscles. "But this needs to be backed up by research," he admits.

While Misra's mission has been to redefine the bmi for Indians (see: interview), official apathy to obesity must go. Policy changes should begin by targeting school children from class five onwards. Their curriculum should include preventive health issues and simple preventive messages on obesity and communicable diseases. Labeling the calorific value on processed food will be a big help. Misra suggests the government should disseminate audio-visual informative and educative messages, to get people in the risk category to go in for a early screening.

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