The Grain Brain and Atkins diets are similar in that both diets emphasize higher fat consumption while minimizing carbohydrates. It is the specifics of fat type where difference exist in comparing the two programs. For example, Atkins diets can be high in fatty, grain-fed meats which are high in inflammatory Omega-6 fats. Often, the grains used to fatten cattle are worrisome as they are GMO derived.  In Grain Brain we advocate the consumption of meat, fowl, and fish, provided that it is grass-fed, free range, or wild caught.  This provides a favorable fatty acid ratio (high in Omega-3 fat).  However meat consumption is not necessary.  The most important thing is that most of your calories come from high quality fat sources such as organic extra-virgin olive oil, coconut oil, avocados, etc., while consuming ample amounts of above ground vegetables, and substantially limiting consumption of carbohydrates.