I know that you feel better when you do not eat. But, as you said, this is very, very detrimental to your body and can have devastating affects on your Lupus!
I agree with Sprant, you should discuss this with your doctor who can prescribe some anti-nausea medications to help you eat and retain your food. The shakes are a supplement to your diet, not an alternative to eating. Drinking only those shakes would also be detrimental!
I hope that you and your doctor are able to find a way for you to reduce your nausea and keep your food down so that you can eat a healthy diet!
Peace and Blessings
Look For The Good and Praise It!