Calorie calculation when baking products with sourdough

Leya from Romania has asked...

I wanted to ask you a question about calorie calculation when baking products with sourdough. 
Not only bread, but pies and cookies and all sorts.

I know that the sourdough starter has the capacity to change the carb proportion and lower it, but I can’t seem to find by how much.

I am trying to calculate all these calories for different products for my friend’s bakery, and I don’t know where to find this info or if anyone has hit this problem before.

My baker friend is now required by law to have all the nutritional markers on her products and she would like to do a pretty accurate job.

Can you help please?