Press 1 grapefruit through a juicer for fresh grapefruit juice. If you don’t have a juicer, you can use bottled grapefruit juice or simply add 1 whole peeled grapefruit to a high-powered blender.
Add frozen banana slices, pineapple, kale and hemp seeds into the blender with the grapefruit. Blend on high until mixture is smooth and creamy.