Martial Arts and weight loss, just wondering?

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I am a practicing martial artist and am currently trying to loose more weight. Since I have started calorie counting for a week now, I have noticed on the days when I am at the Dojang ( our training center) that I am having more cramping in the muscles or weakness. We work out very hard. Is there anyone else, who has been having similar problems while working out and what did you eat or do to help with these issues before working out.

I am new to this sight, if you'd like to friend me encouragement for either you or I would be fantastic. Thanks