I feel out of out gas... I've been strict keto for about 3 months and a half months and I'm down 30 lbs. Recently I've felt like I have no energy. 

I have a pretty physical job rigging for Cirque du Soleil. I climb a lot of ladders, stairs, run a lot of rope, and other physical things. And I'm struggling now 

Is this normal? Or are my calories too low?

I'm currently 5'10" 202.3lbs. And I'm on average around 1500-1600 calories.