To prepare the grapefruit, slice in half and cut out the wedges of one half. Transfer the wedges and whatever leftover juice you can squeeze out of the grapefruit half you used to the blender.
Add the kale leaves, banana, chia seeds and water. Blend at high speed for about 30 seconds to 1 minute or until smooth. Add more water if needed. If you do not use a frozen banana, consider adding ice to make it colder. Enjoy!