A couple of weeks ago I went over the handlebars on my bicycle and broke my collarbone, needed 5 stitches on my forehead, got a little road rash on my hip, and an avulsion (?) fracture on one finger resulting in mallet finger. I'm 54 and have noticed that I'm healing much more slowly than I remember healing when I was a teenager.
Mostly, things are going smoothly and the only thing I'm really worried about is the mallet finger. I've been told to keep it in a splint for 8 weeks and if I accidentally bend it a little before then any healing will have to start over and I might end up needing surgery for it.
If anybody here has had mallet finger, I'd love to hear how it went for you.
Oddly enough I had a similar injury 10 years prior on a different finger and that healed up in 6 weeks as if nothing ever happened to it.
Fat adaptation is a real thing. Endurance athletes focused on longer events will target some of their training around that energy system. This is more complex than can really be explained in an online comment but basically you want to do long training sessions below your lactate threshold in a glycogen depleted state.