Hmm. From my experience you will know if this becomes a problem. You will start to feel very fatigued at the gym and will struggle to do your workouts.
But it also depends on your goal.
If you want to build or maintain muscle then you will need to keep your calories (and protein) in check i.e. not too high, not too low.
At 281lbs, I had lots of fat and some muscle to spare so it did not matter going very low on calories and losing both.
At 170-ish pounds, however, I now need to keep an eye on the muscle so too few calories while doing cardio could eat into that and weight training could have little effect in building or retaining muscle.
I also make sure I get enough protein to help with muscle recovery, retention and building.
So, if you are big I would not sweat it unless you are feeling tired before the gym. If you are smaller looking to build muscle mass, then you may need to check you are getting enough calories and protein.
Last edited by IanG; 04-12-2014 at 12:00 AM.