OK, in the documentary I watched recently, before the volunteers started their 800 calorie per day shake diets, I'm sure the doctors who were running the experiment said that initially, this would cause some physiological problems but that those issues would soon dissipate as the sudden change in their eating habits might be a bit of a shock to their systems, which is fully understandable, but I don't remember exactly what they thought those problems would be, but more than likely it was the issue of their blood glucose levels.
I might need to go back and watch the documentary again but I'm not sure if I saved it or deleted it...!
