What it is: The Paleo diet is based on the notion that modern-day humans should consume whole and/or unprocessed foods in an attempt to eat more like our paleolithic ancestors, because our bodies haven't evolved the way our food supply has, leading to a diet that isn't optimal for the way our digestive system is designed. Off-limits foods include glutenous grains, legumes, sugar, and processed fare that Paleo dieters like to refer to as "Frankenfoods." Bye-bye, Cheetos!
Why it's annoying: Paleo is more than a diet, it's a lifestyle. Which means you can get ready for some major evangelizing when your best friend decides to make the switch to Paleo. On top of all that, Paleo tends to go hand in hand with CrossFit, which means you should familiarize yourself with lingo like "WOD" and "boxes" unless you'd prefer to remain blissfully ignorant.
Key catchphrase: "Eat like a predator, not like prey."
What it is: A 30-day elimination diet intended to help people determine what effects broad food groups have on the body and brain. That means a month without any -- and we do mean any -- alcohol, dairy, sugar and artificial sweeteners, grains, and legumes. So strict is this program that even trace amounts of alcohol in Dijon mustard are forbidden, which means followers must become obsessive label-readers.
Why it's annoying: Combine all the restrictiveness of a gluten-free diet with all the rabid fervor of Paleo-ites and you've got the Whole30. Get ready to hear all about "defeating the sugar dragon," which is Whole30 slang for dealing with a craving for something sweet, and about the life-changing magic of homemade mayonnaise.
Key catchphrase: "That's not compliant."