Deceptive Asian metabolic feature

For the same BMI, slim-looking Asians may have increased metabolic risk compared to Caucasians

By Mylene C. Orillo

LOOKS CAN BE DECEIVING—many Asians and Asian-Americans may look slim with a body mass index (BMI) in the normal range, yet they already have increased visceral fats and may have prediabetes or even frank diabetes.

Visceral adiposity leads to increased insulin resistance, which may play an important role in unmasking an underlying less robust B-cell reserve in Asians.

Dr. Wilfred Fujimoto, currently a professor emeritus of Internal Medicine (Endocrinology and Metabolism) at the University of Washington in Seattle and visiting professor at Jichi Medical University-Saitam Medical Center in Japan, was in town recently for the 2nd ECHO (Experts’ Convergence for Health Outcomes) Summit; and conveyed this unique clinical feature of Asians which increases their risk for insulin resistance.

Dr. Fujimoto led the team that conducted the Japanese American Community Diabetes Study in Seattle, Washington, USA from 1983-2001. In their paper that came out in the early 1960s, he reported that diabetes was much more frequent in Asians in Hawaii than their Caucasians counterparts.

In terms of weight and BMI, Japanese-Americans were not as heavy as Caucasians, yet there are three reasons why they have a higher prevalence of diabetes: Visceral obesity, food intake, and inactive lifestyle.

“Visceral obesity (belly fat), or fat accumulation in the upper part of the body, leads to insulin resistance, and Asians are not able to produce as much insulin,” Dr. Fujimoto explained.

The combination of these two factors—insulin resistance although they are not obese, and increased visceral fat relative to size—led Dr. Fujimoto and team to investigate this metabolic profile of Asians and its clinical impact.

“We have evidence that the lifestyle of Japanese-Americans is not conducive to preventing diabetes. They are very susceptible to it,” said Dr. Fujimoto.

When it comes to food intake, Dr. Fujimoto and his coinvestigators also found that the amount of kilocalories consumed by Japanese-Americans and Japanese in Tokyo were exactly the same.

While the Japanese-Americans were not really eating more food, they were heavier although not as heavy as Caucasians or other groups.

“The only difference was Japanese-Americans were consuming more of the calories as fat, especially animal fat; whereas native Japanese consumed more of the calories as carbohydrates, complex ones, not simple sugars,” said Dr. Fujimoto.

Active lifestyle was the second factor affecting Japanese-Americans in Japan. People in Tokyo commute to work, oftentimes, they take the bus, walk up to train stations, walk up the stairs, walk off the train, walk down, and they’ll either take the taxi or bus to work.

In the US, it’s very common for people get out of their homes, go to the garage, get in to their cars, go to work, park their cars as close as possible to the nearest elevators.

“We found in studying Japanese-Americans in Seattle, they have impaired glucose tolerance or prediabetes. They have the risk of developing diabetes in the near future compared to people who have normal glucose tolerance,” said Dr. Fujimoto.

He reminded the audience that exercise is key to a healthy lifestyle.

“Keeping the food intake down is not enough, you have to exercise and it can release hormones that suppress appetite as well. Diet helps you to lose weight, but to keep the weight off, you should exercise,” he said.

Vital Signs Issue 88 Vol. 4, June 1-30 2016