Optimists say that with enough hard work, patience, and the right nutrition, you can get as big and strong as you want. That there really is no hard ceiling on your potential for whole-body strength and muscularity. To support this rosy outlook, these people often point to top-level bodybuilders and elite college athletes who claim to have never used steroids. I’ve written and spoken about this extensively already, but I wanted to get Lyle McDonald’s take on the limits of natural versus enhanced muscle gain, and particularly how they relate to the fat-free mass index (FFMI). In case you’re not familiar with Lyle, he has been one of the foremost evidence-based fitness researchers and writers for a couple decades now and someone whose work I’ve always liked. He pulls no punches, brooks no bullshit, and makes no apologies when he feels he has the evidence on his side. In this interview, Lyle and I chat about the difference between natural and enhanced muscle gain, what FFMI is and whether 25 is a true natural cutoff, common “fake natty” red flags, and more. Let’s dig in! 11:18 - What is FFMI? 19:27 - Why is a normalized FFMI of 25 a likely ceiling for most people? 53:06 - What is your opinion on the studies on limits with college athletes? 01:16:07 - Would you agree that a FFMI over 25 is a red flag for steroid use? Mentioned on The Show: Shop Legion Supplements Here: https://legionathletics.com/shop/ Lyle's Website: https://bodyrecomposition.com/ Want to get my best advice on how to gain muscle and strength and lose fat faster? Sign up for my free newsletter! Click here: https://www.legionathletics.com/signup/