Wow. I've said it once, I'll say it again. When Zyg speaks, your note pad better be ready. 90% of that Zyg's 9000 posts are helpful quality feedback from years of experience and knowledge. There are guys on this board who should be paid for the advice they give. You're getting it free and being ungrateful to say the least. Bodybuilders aren't fighters, they are body GURU's. Bodybuilders are masters of the body, hence the name of the sport. If you want to change your body, a BB knows how. Nutrition-training-endocrine are subjects they all must master.
Mr. Fish, I don't know who taught you about MMA but my guess is that you actually don't fight or possibly just signed up at a MMA gym and now think you know all. It's not common that a fighter wants to go up in weight class. There are circumstances where they do, but most of them win a title at a lower class or are naturally prodigal athletes. At 6 ft you have many choices of weight classes. I know for a fact your trainer/coach is not telling you to jump a weight class. Fighters are hard pressed to successfully fight their natural equilibrium.
If your goal is to get to 185 from 170, you CAN NOT train like you are prepping for the next fight. Rather, as Zyg has state, you must modify your training to gain size, then, you can go back to fight prep.
"A fighter can often add or shed muscle mass to move a weight class (sometimes two), but there is generally a weight where their cardiovascular and muscular-skeletal structures are healthy and efficient. Fighting outside this "natural" weight class generally means you're giving up strength, speed, or other." - words from a fighter.
Its ok to be wrong bud. We all knew everything once.