Whilst trying to maintain my weights workouts I'm looking to introduce some cardio ready for some potential events in the summer.

I know doing this will have an impact on my muscle gaining/retention but I want to limit this as much as possible.

I can work out how many cals I've burnt in a session but I just don't know what to replace them with.

So say I'm on a rest day requiring 2000 cals to maintain and I run burning 300 cals, should I replace these one 1:1:1 ratio or step up the protein & carbs ?