I like this guy's podcasts -
Ben Greenfield. (Ignore the iPhone app one, unless... you want an iPhone app.)
The podcasts have pretty sensationalist attention-grabbing titles ("Episode #169: Can You Get A Better Workout By Chomping Down On A Leather Strap Like An Ancient Viking Warrior?") but in fact they typically cover a wide range of Q & A topics that are generally treated with intelligence and seriousness. Most are well over an hour, so suitable for a 10K race (self-deprecatory joke), or decent gym session.
He's a triathlete and ex-body builder. Talks a lot about nutrition, exercise, and pretty much everything fitness-related. There are a lot of charlatans in this game but this bloke really knows his stuff, and has quite an engaging, professional style. He has his opinions alright but tends to present different sides of an argument, and he explains his sources in detail. But best of all is the variety. You never quite know what's coming next.
He runs a commercial operation but doesn't lay on the send-me-money-now thing half as thickly as most of them.
Worth a listen, IMO.
RE: Ben Greenfield - worth a listen