Reddit reviews Instinct Grain-Free Dry Cat Food, Chicken Meal Formula, 12.1-Pound Package

Another option is low carb dry food such as this or this.

The second cat I lost was to weight problems, and all other cats I've had couldn't be called fat, but were certainly overweight. Since moving to the low-carb dry stuff, my cats are at a healthy weight.

I interrogated the cats after making this post based on the replies and took some photographs of the event: http://i.imgur.com/nYSIJ.jpg

It took a little bit to get their attention but they knew how much trouble they were in so they went along with it. Loki seemed pretty nervous during the whole thing though and kept behind Artemis. When I asked Loki if he was the norse god of cat vomit, he fled to my wife. She cut off the interrogation and defended his innocence so now I suspect they might be in on it together.

Artemis was very attentive during the interrogation and after it was over he left and went to sleep; however, it was near the scene of the crime. Why would he choose to sleep there when he has plenty of other places more appropriate like the cat tree they were interrogated on? Several of you mentioned that he might be getting revenge for giving him a girl name so I can't rule him entirely innocent.

When we rescued Artemis from the humane society as a kitten they told us he was a girl and we didn't find out he was actually a boy until two weeks later when we took him to the vet because he had a cold.

vinod1978 and IGottaSnake asked why the guilty cat vomited and questioned the food itself. I think that I can safely rule out the food but in the interest of full disclosure.
This is the kibble they eat: http://www.amazon.com/gp/product/B000GLON6U/
Supplemented with this: http://www.amazon.com/gp/product/B003SE12FM/

When I left for work this morning I couldn't find Loki anywhere but Artemis was watching me walk out the door from around the corner at the top of the stairs. I hope I don't come home to something worse tonight.