Preheat oven to 180 degrees C. Lightly grease a 22x13 cm loaf tin and line with baking paper.
In a large bowl, combine sugar, eggs, vegetable oil, pineapple juice and pineapple; mix well. In a separate bowl, sift together baking powder and flour. Stir flour mixture into pineapple mixture. Fold in macadamia nuts. Pour batter into prepared tin.
Bake in preheated oven for 50 to 60 minutes, or until a toothpick inserted into centre of loaf comes out clean.