A body mass index (BMI) of 25, internationally considered the cut-off for a healthy body weight, can no longer be applied to Indians or other South Asians.
The American Diabetes Association (ADA) has said that the BMI cut-off for Asians should be 23, endorsing what researchers and experts have long been maintaining – that the Asian, and particularly south Asian, population comprising Indians, Bangladeshis and Pakistanis are more vulnerable to diabetes even with a lower BMI. In fact, doctors say, a BMI of 23 should set alarm bells ringing for Indians.
BMI is the approximate measure of whether an individual is overweight or underweight, calculated by dividing their weight in kilograms by the square of their height in metres.
“We have been working on BMI specifically for Asian Indians for nearly 15 years and on various international fora for diabetes and obesity it was agreed and accepted that there is a need for a lower BMI cut-off to prevent the diabetes epidemic, said Dr Anoop Misra, chairman, diabetes and metabolic diseases, Fortis CDOC Hospital, Delhi.
“Additionally, the fact that we need to take into account the waist circumference was also acknowledged. Now that ADA, which can be considered even ahead of WHO in the subject, has acknowledged that Asians need to have a lower BMI cut-off is an international recognition of our belief and it will help not just people within the country but also Asian migrants across the world in prevention of diabetes,” said Dr Misra said.
In its January 2015 issue, ADA has recommended that Asians, as against their white counterparts, must screen for diabetes after reaching the BMI of 23. The study by ADA said, “South Asian, Chinese, and black subjects developed diabetes at a higher rate, at an earlier age, and at lower ranges of BMI than their white counterparts. Our findings highlight the need for designing ethnically tailored prevention strategies and for lowering current targets for ideal body weight for non-white populations."
“There have been ample studies from India as well in which we have concluded that our BMI and weight are not equal to that of our western counterparts,” said Dr V Mohan, eminent diabetologist and researcher based in Chennai. “In a consensus statement released by us that comprised diabetologists and bariatric surgeons from across the country, we unanimously agreed that the BMI cut off for South Asians needed to be lower as we have more fat and less muscle in the same BMI category compared to westerners,” Dr Mohan said.
Asians exhibit unique features of obesity – excess body fat, abdominal adiposity, increased intra-abdominal fat and fat deposits in ectopic sites (liver and muscle). Obesity is a major driver for the widely prevalent metabolic syndrome and type 2 diabetes in Asians. Based on percentage of body fat and morbidity data, limits of normal BMI are narrower and lower in Asian Indians than in white Caucasians.
“The recommendation made by the ADA has concurred what we have advocated for long. For a race like ours even at a BMI of 23 there is invisible fat that makes us vulnerable to diabetes compared to any other population. The fact that one should start worrying even with a BMI of 23 needs to be common knowledge,” said Dr Shashank Shah, head of obesity surgery at Fortis Hospitals, Mumbai.
While BMI remains the most widely used clinical method of measuring obesity, in the case of the Indian population, the measurement of waist circumference (WC), too, should be considered as important as BMI if not more.
Shedding light on the best measure for diagnosis of obesity, a consensus statement by Indian researchers said, “Waist circumference should be used as a measure of abdominal obesity with Asian Indian specific cut-offs. Both BMI and WC should be used together [with equal importance] for population- and clinic-based metabolic and cardiovascular risk stratification.”
Dr Anil Bhoraskar, chair elect, International Diabetes Federation, South East Asia, said, “I do not entirely agree with the recommendation made by the ADA. For Asians, and especially our population, the bigger risk factor is the waist circumference, not the BMI. An Indian is more likely to have a BMI of 23 or lower but a greater waist circumference. For men a waist circumference of 90 centimetres and 89 in women is a more telling cut-off.”
# What is diabetes?
Diabetes is a condition that occurs when the body does not produce insulin or is unable to use the produced insulin. High blood sugar or hyperglycaemia happens because of uncontrolled diabetes and, over a period of time, could lead to serious damage to various parts of the body such as nerves and kidneys.
Diabetes is mainly of two types: Type I and Type 2. Type I usually develops in childhood or adolescence and the person has to take life-long insulin injections.
Type 2 develops in early adulthood and is generally due to an unhealthy diet, obesity and lack of exercise. This is the most common type of diabetes.
# What is Body Mass Index (BMI)
Healthcare professionals around the world often use Body Mass Index (BMI) when determining whether patients are underweight, a healthy weight, overweight or clinically obese. People who are clinically obese have a greater risk of developing diabetes, stroke, some cancers and cardiovascular diseases.
# How to calculate BMI
There are two methods for working out your BMI – the metric and imperial systems:
* Metric system
Divide the person’s weight in kilograms by their height in metres square.
Weight 90 kg
Height 1.92 metres
1.92 = 3.61 metres square
90 divided by 3.61 = BMI is 24.93
* Imperial system
The person's weight in pounds, multiplied by 703, divided by the square of their height in inches.
Weight 190 lbs
Height 72 inches (6 feet)
722 = 5,184 inches
190 multiplied by 703 divided by 5,184 = BMI 25.76
# BMI cut-offs as per new recommendations:
BMI of 23 kg/m2 will now be considered overweight (compared to the earlier level of 25)
BMI of 25 will be considered clinically obese (compared to the earlier level of 30)
The waist circumference considered unhealthy for Indian men is now 90cm or 35.4” (it is 102cm/40.1” globally) and 80cm or 31.5” for Indian women (as opposed to 88cm/34.6”).*