Dumb question from a complete beginner

When it says 3 cups of oatbran in a Dukan recipe, what is that in grams or oz?

I looked it up on the internet and it said 3 cups was 450g, but that doesn't seem right!

Whoa there that is an awful lot of oatbran. I have measuring cups so I would presume it means those, which could well weigh as much as 450g - but that amount of oatbran should be lasting you weeks - 1.5 tbspns in Attack and 2 tbspns in cruise.

That's what I thought. Following that conversion rate, it would be nearly a whole packet of 500g. Even though the recipe is to serve 4, it's way too much...