Honestly, you’re better off using a program like Cron-o-Meter. It supports net carbs on the web and the mobile app and does a much better job. See my review of Cron-o-Meter here.
If you do still want to use MyFitnessPal:
- Do the install, as instructed on this page
- Next you’ll want to set up your “macros” in MyFitnessPal:Go to: Home -> Goals -> Change Goals
Select “Custom” and click continue
I have mine set up as 70% Fat, 25% Protein and 5% Carbs.
- You also need to add Fiber as a column to track so the script can calculate Net Carbs for you:Go to: Food -> Settings
Add Fiber to your list of nutrients to track. Make sure you at least have carbs, fiber, fat and protein selected. These are what you need to track for a low carb or ketogenic diet.
It ends up with a cool pie graph and net carbs on the tables (this is for a full day on Ketofood, plus a pepperjack cheese stick as a snack… and 30 minutes of intense elliptical exercise):