This may help, but it may be a PITA to do. There is no one button to click on that I know of to give you what you want. However...:
Go to MyFatSecret (Bar near top of page;>MyFatSecret>MySettings>scroll to bottom of page to Food Diary Nutrition Facts. Check Carbs and Fibers. Now you will have to figure yourself the net carbs.
I hope this works. Oh, and the result of the boxes you check are in your Food Diary MyFatSecret>Food
The Perfect Speed
"any number is a limit, and perfection doesn't have limits.
Perfect speed, my son, is being there.”
Chiang from "Jonathan Livingston Seagull