I don't know if you've ruled this out already but sometimes when there's unexplained weight gain it turns out to be an undiagnosed health issue. I know some meds can cause weight gain as well and doctors frequently neglect to mention when it does. This may not be whats going on in your case but I thought I'd throw it out there.

I also agree with Kevin and Edco. Switching it up on the exercise definitely works wonders as well as tracking daily intake. Sometimes it turns out to be as simple as going back over a weeks worth of food logs and finding a hidden culpret. Although you're from what you've posted you're not overweight by any means so I'd be more concerned about not feeling good and the exhaustion. You could just be vitamin deficient in some area but i'd still get it checked out and not just assume its from the work outs. Good luck, hope everything works out ok

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