I've been cutting for about 11 weeks now, and I've lost 21 pounds so far. I'm 29 years old, 6'1", 212 lbs. I've tailored my diet to the cutting sticky in this forum, and feel like I've gotten good results. That said, I've got a few questions about my cardio.

I run on a treadmill 5 days a week, first thing in the morning on an empty stomach. I take about 5 grams of glutamine with water beforehand (I had some laying around so figured why not). I keep my pace as low as I possibly can without going insane, so like level 5 to 5.5. My heart rate sometimes gets up to 140-145bpm. I've been reading that the optimal heart burning zone is 60-70% of my max heart rate, which would be between 115-130bpm (depending which formula you use).

My question is, how much is running on a treadmill affecting my fat loss? Would it make that much of a difference to use an eliptical machine or bike just to get my heart rate down another 10bpm? Or do you guys think I'm good to keep running? Thanks