You may or may not experience a Detox effect from Green Smoothies or any diet you may try. I am not sure I understand the process but this is something some Doctors and Green Smoothie Experts say happens to most of us.
When you start and continue to drink Green Smoothies, your body does not have to work as hard packing and hiding away toxins in your body, which it normally does to keep some toxins from hurting us. When our bodies do not have to work as hard hiding toxins away, it uses this time to start pulling them out because the levels are lower and flushes them away through our urine, sweat, breath, and other waste.
Our bodies have multiple ways to get rid of waste, our urine, feces, breath, mucus (snot), and sweat glands. The way I understand the process is our body starts detoxifying or getting rid of accumulated wastes. Some books and web sites mentioned the process is a lot like a withdrawal symptoms from a drug addiction. You may feel run down and/or tired in in the first few weeks or for a few days. Or maybe not because you are probably not surviving only on Green Smoothies but are eating other meals too.
For me it happened during my second to third week and lasted about three days. I was tired and felt run down. I had an overly runny nose for a few weeks, three I think, but it was the cold and flu season so it may not be related to Green Smoothies. So if you start feeling tired and run down, it may not be a cold, just a minor body detox. I understand this process is common for almost any diet and maybe eating changes.