no sodium no sugar are best ways to lose weight excersise daily and work your way up do 10 push ups one day then do 12 the next then 14 the next etc… idk why but i seemed when i ate a banana a day i felt less cramping and protein you can go buy shakes and stuff but its good for muscles and muscle devolpment and go call a fitness center those guys are professional and might have some good secrets but that was my diet i was a chubby 185 and now im a built 145 in 40 days
References :

South Beach Diet is the best and easiest to follow that I’ve seen. It’s something you can do forever.

More extreme is the "Warrior Diet". It is also simple, but it involves not eating at all until dinner, and most find that hard to maintain.
References :
http://www.southbeach-diet-plan.com/
http://www.warriordiet.com/

green vegetables, meat, fish, pasta. stay away from energy drinks and things with ungodly amounts of sugar. drink A LOT of water. propel is really good too but not gatorade. as long as you run 4-5 times a week, you will maintain a good fighting weight, while stay fit and energetic.
References :
expirience, webmd

Your best bet is to go to a licensed nutritionist. Allow them to set up a correct and customized program just for you. It will cost some money but without a doubt you will be able to lose/gain weight you want the correct way without harming your body. Fad diets work for some people but not all. If you are serious about fighting as a sport then you should do it right. I have been fighting for a decade and the only reason my body is able to endure the strenuous activity is because of my diet plan. Good luck with your upcoming fights.
References :
over a decade of boxing