Protein is an ally in your weight-loss battle for a couple of reasons. First, protein causes the body to secrete glucagon, a hormone that directs your body to stop storing fat and to burn it. Second, because protein creates a higher ratio of glucagon to insulin, your blood sugar stays more stable, which helps you stave off crashes and cravings.
This brings up one of the most important advantages of an animal-protein diet versus a vegetarian or vegan diet when it comes to fat loss. It’s true that you can get all of the essential amino acids your body needs by eating a combination of grains and legumes, i.e., beans and rice. The individual amino acids will be there, but there’s a downside — they come with a high carb load, and thus a high insulin surge. What’s worse, they do not trigger glucagon production. The higher glucagon-to-insulin ratio associated with an animal-protein diet is key for fat loss, sending the message to burn fat, while insulin alone sends the message to store, store, store that fat.
Of course, some proteins are healthier than others. Although most high-protein diets are not picky about the types of protein they allow, Ultimate You encourages you to be selective. For example, conventionally raised red meat contains significantly more saturated fat and fewer superfats like omega-3 fatty acids than grass-fed beef or bison or with fish. The Ultimate You plan recommends organically raised proteins such as chicken, turkey, game meat, grass-fed beef and bison, and wild-caught fish.
Body By Hardware 
Hi Dr. Brooke,
I’ve read your book and love it. But I am in a quandary about this meat-eating requirement. I understand the science behind the glucagon:insulin ratio. I also know that there are vegan body builders (men and women) and vegan athletes who have very little fat (Mike Mahler comes to mind) and am willing to accept that they are genetically predisposed to being very lean.
I am finding it difficult to believe that I would need to compromise my values (and taste, to be perfectly honest) to lose that last 5% body fat. But on your plan, that is exactly what I would have to do, unless I want to eat eggs at every single meal and snack. So, what do you suggest a somewhat insulin resistant vegetarian eats for protein. I know soy is estrogenic. What about seitan? Low in carbs (8g/serving) high in protein (24g/serving). I’m not vegan, if that’s at all helpful.
Thanks!