Meat was the biggest source of energy for our caveman ancestors—who, of course, went hunting for their own lean, wild game instead of buying prepackaged, grain-fed farm animals at the grocery store. So with Paleo, you’re encouraged to pile on the protein, seeking out fresh, naturally raised, grass-fed and wild-caught varieties while shunning corn- or grain-fed animals and cured, processed meats. Paleo tends to favor red meat in all its glory, from beef to bison, and fish and shellfish are prized too—especially fatty ones, like salmon. (Familiar proteins like chicken, pork, hamburger and eggs are fine too, as long as their sourcing complies with the standards above.)
But wait, this sounds like too much meat…right? Critics of the diet slam its saturated fat content, but Paleo experts claim you’re retraining your body to rely on fat—not carbs—for energy. “In our world, it’s ridiculous that you would avoid eating saturated fat, provided you are also cutting back on processed carbs and the types of sugars that raise insulin and cause havoc,” says Mark Sisson, a former world-class marathoner, Ironman triathlete, and author of The Primal Blueprint, one of the most popular guides to Paleo-style eating.