Why does an astronaut's diet consist mainly of carbohydrates?

The astronaut´s diet does not consist of carbohydrates - the main idea of the diet is to avoid carbohydrates. It consists mainly protein. The idea of avoiding carbohydrates is that if organism doesn´t get carbohydrates then it starts using fat - both: the one we get with food and the one we have in our bodies.

So, astronaut´s diet does not consist of carbohydrates!