After doing HIT/HD for a few weeks you won't gain any weight despite getting stronger each workout. I've done 430x20 in the squat at a bodyweight of 160. Nothing was more frustrating than getting stronger with no increase in size.
In my experience, what usually happens is no matter what i'm doing exercise, the more I eat, the better gains I get. now granted.. I was on the skinny end.. going from 135/140 to 165/170. The gains, i'd say, are mostly muscle... hard gained. And no..you can't avoid getting fat in my experience. That was actually what held me back for awhile..I was afraid to really pack on the calories. It's no big deal though.. you just add the muscle, then do a week or 2 of cardio and you're set...
Well, i was able to gain muscle without fat and even maybe losing some fat, i went from 137 to 154 in about 8 months, I eat just a little above maintenance. I guess i would be much bigger if i ate around 500+ calorie above maintenance but i try to stay only between 50 and 250 cals above it. I absolutely hate cardio, thats why i dont want to bulk/cut. I try to get as much protein as i can and as little fat as i can.
It is definitely possible to become stronger without gaining any muscle or fat. I also conducted a 2 month HIT program (one set to failure around 8-12 reps, increase weight every workout) and made tremendous gains in strength without any increase in size. It's a good thing I found HST! There is a more scientific reason for how your muscles get stronger without growing but basically it has to do with your CNS becoming more efficient as you do an exercise over and over.
i have had a few athletes get signicantly stonger while dropping down in weight class coach hale www.maxcondition.com MaxCondition Forum where practicality meets Science