Friend's obsession with working out has begun to drive other friends away from each other. Advice?

Summary: A long time friend of mine and I started weight training five months ago. While we are both very much into it, he has taken it to a new level. Lifting weights and showing off snapchats of him working out have become the only thing he has been interested in for about a month now. This is annoying our other friends and they are starting to avoid hanging out with us due to how annoying my friend has gotten with his lifting obsession. Advice for how to bring my friends back together?

Full version: Back in May, my friend and I (We will refer to him as Mikey from now on) both joined gyms and started weight training. I also signed up for a weightlifting class this year, so we are both very into it. We still workout together frequently and give each other advice, and It's become something Mikey and I talk about almost all of the time. Mikey is much, much more obsessed with his weight training than I am, and it's starting to drive away some of our friends.

Recently, a friend who has been close to both of us for a long time has recently stopped talking to us. He avoids seeing us in between classes, going to the same parties as us, general hanging out, etc. and it's because of my friend's constant talk about how much he can bench. When we do end up striking up a conversation with this friend, Mikey does nothing but pressure him into joining the gym and to start working out. What should I do to stop this?