I saw a Cat eating lots of grass

I was having lunch and I couldn't help but stare at this cat who was on a grass patch beside me. He was munching and gobbling away the grass for like 30 minutes!
That's weird... I know cats eat plants once in a while but this one was gobbling grass like a goat. And I saw him choking once in a while.
I wonder why he's eating so much grass...

Cats will eat a lot of grass if something has upset their stomach - it'll make them vomit. Smaller amounts adds some fiber to help things pass. Plants serve as a source of B9, too.

Jake used to eat grass but not for 30 minutes straight. He always had a little bit each time we went outside this summer though. He also likes bananas.

Cats will eat grass when their stomach is upset for sure. You can buy pet grass for inside kitties as well they really seem to like that.

My only guess is he was hungry or upset stomach.