The Master Cleanse is not a true fast. However, I do not consider it going into starvation mode either. The Maple syrup provides plenty of glucose when the cleanse is done correctly. Lemon juice provides magnesium, potassium and sodium. Simple sugars are needed to allow electrolyte minerals to be properly absorbed by the body. Properly done The Master Cleanse can be a valuable tool, especially for those who cannot or are not ready to attempt water fasting. Still, remember, technically it is a cleanse and not a true fast. Just as with juice fasting, there are many benefits including rapid weight loss associated with nutritive "fats". However pure Water Fasting is best for healing and deep cleansing.