Well , I do kyokushin , i am 69.5 kg ( supposedly ) and I am a short guy , I don't like to watch my food consumption , soooo.. Basically , I am just like you . I always have the problem of loosing weight before tournaments which is really a hard thing to do , my height is 170 therefore I can't fight in the middle weight , if you are any taller then yeah , gain some weight if you want to , but you will do better in the lightweight , I had to fight in the middle weight few times and believe me , it's not as easy as it sounds