What is AIP?
The Autoimmune Protocol, or AIP, is a specialized version of the Paleo diet, with an even greater focus on nutrient density and even stricter guidelines for which foods should be eliminated. Foods can be viewed as having two kinds of constituents within them: those that promote health (like nutrients) and those that undermine health (like inflammatory compounds). Some foods are great diets because they have tons of benefits with very little or no constituents that undermine health—good examples of these superfoods are organ meats, seafood, and most vegetables. There are other foods that aren't so great because they have a ton of problematic compounds—good examples are gluten-containing grains, peanuts, and most soy products.
The biggest difference between a standard Paleo diet and the Autoimmune Protocol is where we draw the line between “acceptable” foods and “unacceptable” foods in order to get more health-promoting compounds and fewer detrimental compounds in our diet. People who are typically quite healthy can tolerate less-optimal foods than those who aren’t. You can think of the Autoimmune Protocol as a pickier version of the Paleo diet; it accepts only those foods that are clearly healthy.