Originally Posted by Steven Wingo
If you are doing it only 2x per week, I doubt there is much risk you will start to burn away muscle as long as you are eating enough. I say that assuming you are not out there running 15k with her or something like that and that this is a relaxing run of 15-20 minutes or so. That is not a lot of running.
Each person may be different as well so you will just have to monitor it. Some people who have trouble keeping on weight have to be very careful, such as me--I drop weight fast when doing a lot of running or cycling. But for me that was running 6-8 hours weekly or cycling 12+ hours weekly. That is very different than a couple of runs a week for 15-20 minutes. I'd say go spend the time with your wife running with her, make sure you eat enough, and don't worry about it.
My purpose is to help aid fat burning and increase cardio. I don't drop weight that easily, nor do I gain it easily. I am somewhat stocky. But have a "naggingly small" spare tire I'm working on getting rid of.