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You need more calories. If you are strength training and only consuming 1400-1600 calories, that is most likely not adequate. If you are Celiac, you are not absorbing everything you need from a nutrient perspective already, then you burn the rest up on exercise... Additionally, have you drastically reduced your carb intake? Hopefully not if you are active. You'll need those carbs. I inadvertently cut my carbs drastically. When I went gluten free, I mistakenly was eating an Atkins-esque diet without meaning to. I didn't know the right way to cut out gluten and ended up not getting carbs. I eventually started experiencing Ketosis. Bad stuff. I dropped to 137 lbs and I'm 5'11.
I started eating 2800-3000 calories per day and stopped working out altogether to get my weight up. 7-8 months later, I'm checking in at 172 and have finally started biking and went for a run last night. Anyhow, when my caloric intake was down along with my weight, I was tired, anxious, and depressed.
You may not be in the same boat as I was but you are working out much harder than I was and you aren't getting enough calories in my opinion but then again, I don't know what your fitness/health goals are...
