OBJECTIVE -To determine whether diet and endurance exercise improved adiposityrelated measurements in Japanese Americans with impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS -This study compared the effects of an American Heart Association (AHA) step 2 diet (Ͻ30% of total calories as fat, Ͻ7% saturated fat, 55% carbohydrate, and Ͻ200 mg cholesterol daily) plus endurance exercise for 1 h three times a week (treatment group) with an AHA step 1 diet (30% of total calories as fat, 10%

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... saturated fat, 50% carbohydrate, and Ͻ300 mg cholesterol) plus stretching exercise three times a week (control group) on BMI, body composition (% fat), and body fat distribution at 6 and 24 months of follow-up in 64 Japanese American men and women with IGT, 58 of whom completed the study. RESULTS -At 6 months, the treatment group showed significantly greater reduction in percent, body fat (Ϫ1.4 Ϯ 0.4 vs. -0.3 Ϯ 0.3%); BMI (Ϫ1.1 Ϯ 0.2 vs. -0.4 Ϯ 0.1 kg/m 2 ); subcutaneous fat by computed tomography at the abdomen (Ϫ29.3 Ϯ 4.2 vs. -5.7 Ϯ 5.9 cm 2 ), thigh (Ϫ13.2 Ϯ 3.6 vs. -3.6 Ϯ 3.0 cm 2 ), and thorax (Ϫ19.6 Ϯ 3.6 vs. -8.9 Ϯ 2.6 cm 2 ); and skinfold thickness at the bicep (Ϫ2.0 Ϯ 0.6 vs. 1.1 Ϯ 0.6 mm) and tricep (Ϫ3.7 Ϯ 0.8 vs. -0.9 Ϯ 0.6 mm), which continued despite moving to home-based exercise for the last 18 months. CONCLUSIONS -Diet and endurance exercise improved BMI, body composition, and body fat distribution and, thus, may delay or prevent type 2 diabetes in Japanese Americans with IGT.