For the same BMI, slim-looking Asians may have increased metabolic risk compared to Caucasians
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.
Diabetes prevention program
The Diabetes Prevention Program in the United States enrolled more than 4,000 individuals who had impaired glucose tolerance.
About 45 percent accounted for minority origin (Blacks, Asians, Hispanics, Native Americans). In the Asian group, reesearchers found out that even if the lifestyle was not very vigorous—just maybe walking about half an hour, five days a week, and then consuming a diet that is reduced in fat—they would lose about five to 10 percent of excess weight.
“If they are trained to exercise vigorously and consume a diet that is reduced in animal fat, more likely the many risk factors that are related to the development of type 2 diabetes can be reduced,” said Dr. Fujimoto.
He added that the weight loss is enough to reduce the risk of diabetes – about 58 percent as compared to a controlled group. Lifestyle changes have broad effects for diabetes prevention and this is shown in a number of other studies as well.
A set of guidelines was developed and literatures on BMI were reviewed that led to recommendations that the BMI cut-off should be lower in Asians.
Dr. Fujimoto said that the American Diabetes Association proposed a BMI of 25 or greater as a basis for screening for increased metabolic risk. “For Asian-Americans, it should be 23, a lower BMI cut-point,” he said.
Based on their data and further studies on visceral fat distribution, their team proposed that some ethnic groups are more prone to gain weight with urbanization and westernization.
Asians constitute an ethnic group that seems to be especially at risk when exposed to these lifestyle changes. Their weight gain, however, does not appear to be the real issue. Rather, their apparent propensity to accumulate central (visceral) fat seems to be the risk factor that increases their risk to develop type 2 diabetes.
Exercise over diet
In another lecture during the ECHO summit, it was proposed that te risk for CVD is lower in those who exercise regularly, at least in women.
Looking at women who are overweight, exercising according to recommendations yielded better outcomes, compared to women who don’t exercise at all though they may maintain their body weight and diet.
“It means that exercise is the main target and diet is maybe secondary,” said Dr. Amos Pines, the cofounder of the Israel Menopause Society and is currently associate professor at the Sackler Faculty of Medicine in Tel-Aviv University.
Dr. Pines added that there should also be a balance between the amount of calories one eats and how he spends it.
During the discussion with media, Dr. Fujimoto said that while walking in the mall or “malling” has become one of the most popular pastimes for everyone including Filipinos, unless it’s done briskly for half an hour without stops, it doesn’t count as a real exercise. He recommended though using the stairs more frequently.
Dr. Fujimoto reminded the audience that exercise is still key to a healthy lifestyle. “People have gone from one diet to another and you would notice that for a few days, you can lose up to 5 lbs., but then you regain it because just 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.