Hazbin
I think the chemist nailed it partially on the head, but I think Cortisol is also part of the problem.Believe it or not, when the body releases cortisol due to stress, a person can lose huge amounts of weight.I seen a study on meth addicts who would lose up to 15lbs in one day from andrenaline output, and the anxiety of cortisol.
I am not saying your a tweeker but most tweekers are paranoid.So there body releases tons of cortisol.
Hazbin I think when your getting ready for a show you get so anxious and stressed, because you think your going to screw up or your not going to peak that your body releases tons of adrenealine and Cortisol.
I guarantee if you leanr to relax and take it easy, you will be just fine.Learn to meditate, or just chill.
You look great, your just letting your emotions get the best of you.
I have been there.I have been in the best shape of my life then got nervous, and strresed out to only watch my vacularity fade right before my eyes.