Carbohydrates are a complex set of foods that come in three forms:
Monosaccharides (Glucose), Disaccharides (Cane Sugar) and Polysaccharides (breads). All carbohydrates can be broken down in the body into sugars.
It doesn't make a lot of difference to your body in which form you consume these carbohydrates.
The total calorific value is the same and all carbohydrates affect your blood sugar levels in a negative way.
Therefore the "healthy" grains like bread, pasta and rice we are all encouraged to eat actually eventually affect our blood sugars in a similar way to sweets and sugar - all the time contributing to diabetes, obesity and possibly even cancer.
Contrary to what we are taught in nutrition or by our doctors, refined carbohydrates are not an essential part of our nutrition. The only carbs we need to eat are vegetables and fruit.
They are not necessary "building blocks" and the body can survive very well on just protein and fats and these types of carbohydrates - even athletes!
By limiting your carb intake to your fruit and vegetables means you get the minimum carbohydrate intake but with the maximum input of the important minerals and nutrients.