The invention provides methods for the treatment of cancer, reduction of cancer risk, or prevention of cancer in a companion animal, comprising: identifying the companion animal having cancer or at risk for cancer and feeding a dietary formulation in a therapeutically effective amount to the animal. The dietary formulation can comprise 20% to 60% protein; 10% to 40% fat; 10% to 50% carbohydrates; and 0.01% to 5% alpha-amylase inhibitor, and optionally 1% to 50% resistant starch. The therapeutically effective amount can be effective for the treatment of cancer, the prevention of cancer, or the reduction of cancer risk in the companion animal by lowering the postprandial blood glucose of the companion animal as compared to the postprandial blood glucose of the companion animal ingesting a comparable dietary formulation that excludes the alpha-amylase inhibitor.