Asian Americans lower insulin resistance on traditional diet

A Joslin randomized clinical trial now has demonstrated that both Asian Americans and Caucasian Americans at risk of type 2 diabetes who adopted a rigorously controlled traditional Asian diet lowered their insulin resistance. (A leading risk factor for developing the disease, insulin resistance is a condition in which the body struggles to use the hormone insulin, which helps to metabolize sugar.)

Moreover, when both groups of participants then switched to consuming typical western fare, the Asian Americans experienced greater increases in insulin resistance than did the Caucasian Americans, says Dr. King, senior author on a paper on the study published in the journal PLOS One.

The 16-week pilot trial was completed by 24 East Asian Americans and 16 Caucasian Americans, who had an average age of 34 and were either of normal weight or overweight but not obese. All the volunteers had a family history of type 2 diabetes or another indication of diabetes risk such as gestational diabetes.

For the first eight weeks, all the participants ate a traditional high-fiber East Asian diet with 70% of calories from carbohydrates, 15% from protein and 15% from fat, and providing 15 g fiber/1,000 kcal. The food was prepared fresh by local chefs and delivered every two days. “Three meals and one snack were included each day, and we made sure that they were nutritious as well as very tasty,” says Ka Hei Karen Lau, a Joslin dietitian and certified diabetes educator.

For the second eight weeks, 33 of the volunteers (20 Asian Americans and 13 Caucasian Americans) transitioned to a typical low-fiber western diet with 50% of calories from carbohydrates, 16% from protein and 34% from fat, and providing 6 g fiber/1,000 kcal. Seven volunteers (4 Asian Americans and 3 Caucasian Americans) stayed on the traditional Asian diet to act as controls for the study.

Meeting with the trial participants every two weeks, the Joslin team adjusted individual diets as needed to keep their weights relatively steady, so that changes in their metabolism were not driven primarily by changes in weight.

Maintaining those steady body weights for trial participants was a challenge, King remarks. “It was almost impossible to prevent people from losing weight on the Asian diet, and that was not because the food wasn’t good!” he says. “And almost everybody gained weight on the western diet, and we had to work very hard so they didn’t gain too much.”

The researchers suggested that the combination of high fiber and low fat in the traditional diet may