Wednesday, October 8, 2008

Fat Asians

Obesity is a huge emerging problem that I talked about last month. The most common measurement is BMI, which is flawed in many ways. BMI or Body Mass Index measures your weight compared to your height. It does not take into account muscle or particularly kind of fat (healthly or non-healthly). Muscular men seem to be considered overweight (>25 kg/m^2) or obese (>30 kg/m^2) even appearing very fit and having very low % body fat.

Muscular men are not the only ones mischaracterized by this measure; a 2004 Paper from the Lancet suggests that Asians are at greater risk of obesity related diseases (cardiovascular disease, diabetes) at lower BMIs than Caucasians. Asians appear to have increased subcutaneous and upper body fat that is not captured by the BMIs. These fat measurements can be captured in other ways like body fat percentage....

a study in new york measured the following:
Body Fat % at BMI of 25 kg/m^2
Males: Whites: 19.2, Asians: 23.6
Females: Whites: 34.2 Asians: 36.8

Based on the these finding in others the WHO recommended (pdf) the following:

"For many Asian populations, additional trigger points for
public health action were identified as 23 kg/m2 or higher,
representing increased risk, and 27·5 kg/m2 or higher as
representing high risk. The suggested categories are as
follows: less than 18·5 kg/m2 underweight; 18·5–23 kg/m2
increasing but acceptable risk; 23–27·5 kg/m2 increased
risk; and 27·5 kg/m2 or higher high risk."
To summarize/oversimplify, an overweight Caucasian has a BMI over 25, while an overweight Asian has a BMI over 23. No worries my deceivingly chubby Asian friends, the WHO also mentions that the overweight cutoff varies by Asian population from 22-25. My suggestion for those of all races is to get your body fat percentage measured along with your waist/hip ratio - assuming you need more motivation to eat healthy and exercise (or if you just like numbers). Hopefully in the future the health community can improve on the BMI measure and use a less archaic measurement that is less misleading.


allovertheeowl said...

It's ironic because I think the stereotype is that Asians are skinny and small compared to their fatter American counterparts.

Japan has instituted fines for businesses who have employees with excessive waistlines...

What do you think is the cause of the difference in body fat proportion between Caucasians and Asians?

Dan said...

yeah that's interesting what Japan has done, i think it might be a bit extreme for my taste.

Just a guess - but I think it might have to do with how the ancestors of each had to evolve. Maybe caucasians were in areas that were more difficult to hunt/farm, and only those with better fat storage survived. Asians maybe had it easier and didn't need to develop that fat protection. My history is a bit weak so that could be off - but i still it somehow has a natural seletion basis to it.

Bo said...

that-a-way dan explain everything with evolution.

Very interesting stuff. I definitely am surprised reading this when Asians are the only race identified under the US Census not having Heart Disease as their number 1 killer. Also, they have a lower rate of diabetes compared to other major races in America.

Of course lifestyle differences will alter health outcomes. But for Asians to be at a higher risk for heart disease and diabetes, yet have a lower mortality in both categories is confounding.

Within the next few decades as we Americanize more Asians they may face large problems Heart Disease/Obesity/Diabetes.

Dan said...

"Of course lifestyle differences will alter health outcomes. But for Asians to be at a higher risk for heart disease and diabetes, yet have a lower mortality in both categories is confounding."

I don't know if you can say Asians are at high risk for those diseases, just that BMI does a poor job of measuring Asians. I feel like that this research is saying that an asian and a caucasian could have the same lifestyle habits and the caucasian will probably have the higher BMI. However that doesn't mean the caucassian is more at risk for CHD/Diabetes than the asian.

Another thing to consider is that there are much fewer overweight/obese Asians compared to Caucasians (i think in both body fat and BMI measurements). Their diet is better, and so their mortality rate of those diseases are lower as of now.

I think the big trigger is consumption of animal fat. that at least plays a big role in certain cancers, and why their incidence is higher in the US than in some asian countries.