Besides the fact that beef and other red meatisn't great for you, deciding to eat a restrictive diet that consists of just one food or food group — and puts all others in the "off-limits" category — is generally a bad idea, because it harms your relationship to food. Food is more than something we consume for fuel; it's meant to be enjoyed for the flavor and pleasure it brings us. While there may be some days when you really crave a juicy steak or a thick hamburger, there may be others when you're jonesing for a satisfying salad or piece of salmon. And you shouldn't deny your body and your cravings simply because you've bought into a carnivore diet belief system.