Detoxification happens at different levels during a juice fast. The first week is the hardest bit, and then everything is downhill from there. This is an estimation of how the body detoxes, but please note that no two humans were created equal, and this will differ in each person, since you have an interaction of medication, environment, past diets, health, etc. Also, do not let this discourage you. Some people experience very little symptoms, and some experience more than what’s mentioned here.
The following stages were written by Tom McGregor, author of Eating in Freedom.
Stage 1 (Day 1 To Day 2)
On the first day of fasting, the blood sugar level drops below 70 mg/dl. To restore the blood to the normal glucose level, liver glycogen is converted to glucose and released into the blood. This reserve is enough for half a day. The body then reduces the basal metabolic rate (BMR). The rate of internal chemical activity in resting tissue is lowered to conserve energy. The heart slows and blood pressure is reduced. Glycogen is pulled from the muscle causing some weakness. The first wave of cleansing is usually the worst.