If you’ve spent 15 seconds in a CrossFit box, you know what Paleo is. If you’ve spent 30 seconds, you’ve probably already cooked your first batch of Brussels sprouts and bacon on a bed of purple potatoes.

But what is this “keto” thing that’s popping up all over the Internet (and in many a CrossFitter’s kitchen)?

The staples of the two diets are actually pretty similar, and the limitations line up almost exactly. People on both diets are constantly eating butter by the pound — in their coffee, on their steaks and sometimes on its own like a slice of quadruple-cream brie (hold the cracker).