I've tried several different health and fitness podcasts and wind up eventually unsubscribing after a while. The main ones I've tried are Jillian Michaels' podcast, which I listened to for years off and on but I go through stages where I get frustrated with what she focuses on. I like her personality on there, and I've liked several of her cohosts and guests, but I want more actual fitness content than she provides these days.
I've also tried the Cut the Fat podcast with Ray Hinish and Blythe Wagner, and I appreciate their personal expertise in both food- and exercise-related issues. However, they've started to shift more of their focus to their paying club clients, and I don't appreciate the hard sell there. I also feel like after listening for several years, I've learned about all I can from them. If you want a more science-based podcast that really does keep its focus on food and workouts, though, this is a pretty solid choice.
What I'd honestly love is a podcast that discusses specific types of exercises in depth, describing what muscles the move benefits and how that can translate to fitness goals, but I've never found anything like that.