Ideally one should eat a wide variety of proteins from as many animal sources as possible. One need not and should not avoid fatty cuts of meat, particularly if consuming pastured sources. An often overlooked piece of the paleo diet in popular culture is an over-reliance on standard cuts of meat, at the expense of organ meats, bone broth and other collagen sources. For more information on the historical and practical aspects of consuming a more balanced protein intake, check out the Weston A. Price Foundation. If weight-loss is a goal, protein makes you feel satisfied between meals.
Another 2014 study in the European Journal of Clinical Nutrition compared the effects of the Paleo plan to those of a standard low-fat diet on 70 obese, postmenopausal women. After six months, the Paleo group lost 14 pounds on average, while the other group lost nearly 6 pounds. After a year, the Paleo group had lost 19 pounds on average, and the low-fat dieters had dropped 10 pounds. A year later, both groups had regained some weight: The Paleo group was still down 10 pounds, while the low-fat group had dropped an average of more than 6 pounds.
Greg Glassman and Lauren Jenai founded CrossFit, Inc. in 2000. The company was conceived a few years earlier, in 1996, as Cross-Fit. The original CrossFit gym is in Santa Cruz, California, and the first affiliated gym was CrossFit North in Seattle, Washington; there were 13 by 2005, and today there are more than 13,000. Coaches associated with CrossFit include Louie Simmons, John Welbourn, Bob Harper, and Mike Burgener.