Are carbohydrates essential?
Carbohydrates are an important source of energy providing glucose for the body, and public health advice recommends that half our fuel from food should come from carbohydrates.
Some cells in the body need a steady supply of glucose to function effectively, such as red blood cells and the brain. In the absence of glucose from carbohydrate the body can switch to making glucose from protein. While this is okay for a short period, long term it can have adverse effects on the body.
More on the truth about carbs via NHS choices website.