This certainly could have a lot to do with it, not sure why you're being down-voted. I've seen fighters at my muay thai gym in heavier weight classes drop 20 po

This certainly could have a lot to do with it, not sure why you're being down-voted. I've seen fighters at my muay thai gym in heavier weight classes drop 20 pounds to make weight for a fight in a month. You'll usually cut salt and carbs and manipulate your water weight to make weigh-in. It's certainly not at all healthy, but not uncommon. I've even had days after training where I'm 4-5 pound lighter after class from all the sweating and I'm only in the low 150s range.