Study on Asians found that individuals with normal weight were far less likely to die from cancer, heart disease or other causes than those with very high or low BMI.
If you are an Asian, you don't have to be obese to suffer from obesity related diseases. Are Asians on a different obesity scale?
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Dr. Wei Zheng of Vanderbilt-Ingram Cancer Center, Tennessee and his colleagues observed that most studies evaluated the association between BMI and risks of death from specific causes on European populations but the validity of these criteria in Asian populations is yet to be determined. According to Dr. Zheng, "A large number of Asians are very thin and the impact of a severely low BMI on the risk of death has not been well evaluated until now". This observation made them perform pooled analyses to evaluate the link between BMI and risk of death in Asians.
The study which was conducted as part of the "Asia Cohort Consortium" included health status and mortality information of more than 1.1 million individuals from East and South Asia over a period of 9.2 years. BMI was defined as weight in kilograms divided by the square of height in meters.
In East Asians including Chinese, Koreans, and Japanese, the lowest risk of death was noticed among individuals whose Body-Mass Index (BMI) was in the range of 22.6 to 27.5, which is considered as normal to slightly overweight. The risk increased in people with BMI either higher or lower than that range.
East Asians with a raised BMI of 35.0 or higher had a 50 percent higher risk of death. Interestingly, the study found that the same does not hold true for Indians and Bangladeshis. This goes to show that a high BMI does not affect all ethnic groups in the same way.
"The most unexpected finding was that obesity among sub-continent Indians was not associated with excess mortality," said Dr. John D. Potter of Fred Hutchinson Cancer Research Center, Washington, who was one of the researchers in this study. He further added, "This may be because many obese people in sub-continent India have a higher socioeconomic status and so have better access to health care."
Associate Investigator Paolo Boffetta, MD, Professor at Mount Sinai School of Medicine, New York explained, "Severe underweight was highly prevalent in Asia in the past, and we can still observe its important impact on mortality. However, prevention of overweight and obesity deserves the highest priority."
John D. Potter added, "This confirms that most people are at a higher risk for dying early if they are obese and is a clear message not to gain weight as we age".
The authors concluded that their study provides strong evidence of biologic relevance that weight contributes to a higher risk of death. Being underweight is associated with increased risk of death in all Asian populations. However, the excess risk of death associated with a high BMI has been seen among East Asians but not among Indians and Bangladeshis.