gain muscle, keep fat off
OK so stick with me here cos this might get a bit long-winded.
I started boxing like a year ago, 76kg for 1m76, thought I was buff but found out I was really just a fatass. I lost a bit of weight involuntarily by training and stayed around 72 kg for a while, and my trainer was fine with that, said I could fight at middleweight or welterweight.
Then about January this year I changed trainers and my new trainer grabs my tummy and says 'this is fat.' I'm like OK, because by this time I'm getting serious about boxing and am willing to train a lot.
Now I'm around 65 kg after training, though not dehydrated. I walk around at about 67 kg. My trainer says that if I don't want to fight at lightweight (which I really do not want to do) I can cut back a bit on the running and gain a few kilos.
This is all good cos I find myself a little too thin now. I have a brilliant six-pack and pretty good power in my arms, but I'd really like to put on those extra kilos where they are needed and buff up a bit.
So my question is, what's the general template for gaining muscle mass while keeping off the extra fat and even possibly shedding some more? I strength train twice a week and eat relatively healthily, never had to diet or anything. So what burns fat and what burns off muscle? What builds fat and what builds muscle?
I know this is a pretty broad question so any legitimate help would be appreciated. Cheers.