3 cups of low carb veggies is fine- IMHO you could have 6 cups as long as you count the carbs.

I just checked and their cups are closer than I thought;

Metric cup (Australia and almost everywhere else) = 250 mls

US cup = 236.588395339209 mls

- so close enough, although as I say, I have never tried cramming things into cups, weighing is much easier.

Cheers,

Malcolm