Maintenance Mode, Low BF% and Running

TinaDay1114

So I'm at my goal weight (YAY), and have dropped from 18% BF to 12% doing a combination of running, circuit training, and spin over the past 9 months. Now I'm in maintenance mode, and have ALWAYS eaten back my exercise calories -- so I'm now eating about 1,800 - 2,200 in a day, depending on whether I work out or not. I even go over sometimes when I'm especially hungry.

I usually don't eat before my workouts b/c the thyroid meds I take need at least a 1/2 hour without food, so timing breakfast after an hour's workout worked out perfectly for me. But I'm noticing that I'm struggling through my workouts over the past month.

Here's my question (to those of you who know more about physiology than me):
When your body fat drops below a certain %age, does it NEED morning calories to get through an AM workout b/c there's not a lot of reserve there to begin with? Or is that a fiction?

I did sneak in a banana halfway through my circuit training the other day, and felt much better...