In the first study (Study 1), 4-wk-old Sprague-Dawley (SD) rats were fed high fat diets containing casein, Alaska pollack, yellowfin tuna, or chicken as the protein source for 28 d. The purpose of this study was to compare the effect of Alaska pollack protein with other animal proteins (casein, yellowfin tuna, and chicken) on the prevention of visceral fat accumulation. We found that Alaska pollack protein was a more potent inhibitor of visceral fat accumulation than the other proteins (p<0.05). In the second study (Study 2), we determined the quantity of Alaska pollack protein needed to have an effect. To test this, 4-wk-old SD rats were fed diets containing different percentages of Alaska pollack proteins (0, 3, 10, 30 or 100%) to replace casein as the protein source for 28 d. The diets with 30 or 100% Alaska pollack protein as the protein source prevented visceral fat accumulation and elevated plasma adiponectin levels. Based on these findings, an inhibitory effect on the accumulation of visceral fats can be achieved by consuming a diet in which 30% or more of the total protein content comes from Alaska pollack.