Well, there's more than just a simple yes/no answer to gaining lean muscle mass while on any sort of caloric deficit. One, you're on keto, so your energy is coming from fat synthesis vs. carbohydrate synthesis. Gilg is a big guy with a lot of fat currently, so his energy stores should be fine as long as he is in keto and not bouncing back and forth in low carb. Second, he's not lifting a lot of weight. What he's pushing, especially given his size, are largely cardio numbers. When someone is fat and able to actually walk around, they generally -have- to have some muscle mass and strength because of their shear weight. As long as you aren't Baron Harkonnen, a fat dude is going to have much stronger leg muscles than a skinny dude who isn't a super consistent weightlifter. Arms and upper body might be a different story, but a lot of the reduced "power" is going to come from a vastly compromised cardiovascular system. The strength gain is mostly just maintenance and a reduction of secondary weight (flaps o' fat) in the very large, especially if they aren't putting up "big" numbers. He might have what are referred to as newbie gains, as his body acclimates to lifting stuff and being active. This is basically expected in anyone who has taken a long time off lifting or whom has never/rarely lifted before.
The thing is, Gilg is almost certainly increasing his lean muscle mass while he cuts, because he's not doing marathon sessions of lifting, and is mostly doing cardio while holding weights. Which fits into a fat-loss regimen absolutely perfectly. His body isn't looking for muscle to break down with 15-20 minutes on an elliptical. It most certainly isn't breaking down muscle stores for energy lifting 140lbs in a power lifting bench routine (5x5? or something. I'm lazy and don't want to check) nor curling 25s occasionally while doing LoL. Fat synthesis for energy happens more rapidly on keto, and his relative intensity is almost entirely heart related at his weight, so he shouldn't be worried about losing strength. If anything, as he reduces his weight down to only slightly obese levels (260 or so given his weight/size) he should notice positive strength gain almost across the board. Simply being lighter is going to mean he's going to be able to put more on the various bars because he's no longer carrying around a cheerleader on his back while walking around normally.
The people who I personally argue about worrying regarding their gains while at a caloric deficit are people who are losing at a reasonable rate (1-2lbs a week) and concerned when they spend 2 hours in the gym lifting that their numbers aren't going up or are going up very slowly. Or in a lot of cases, going down. Even on keto, there's some physical limits to how much energy you get from fats. And especially on keto, this means you go right into proteins when that threshold is hit/surpassed. This is why you should probably stick with a higher protein content if you are an active person while cutting weight on keto. 160g is great for someone losing at a normal rate and they have roughly 80lbs of lean muscle mass on them (closer to 60, but whatever) If you are on keto and actually spending a decent to reasonable amount of time in the gym, you definitely need to consume more than that, or you are going to notice a decrease in strength over time, because odds are you are burning through your protein intake to keep energy going and there's not a ton of proteins (well, amino acids) left over for muscle repair. And 2 hours in a gym is going to require a lot of muscle repair if you aren't a bro-lifter.
The other type of person is someone who is just low carb. Low carb but non-ketosis diets are -shit- for lifting, across the board. If you are just in a low carb diet (post keto atkins, for example) then it is absolutely insane to expect "gains" while at a caloric deficit once you are out of newbie gains. And even your newbie gains will be truncated. This is especially true for people doing marathon type exercises (hour+ of cardio) or lifting heavy. Without carbohydrates or the enhanced fat synthesis speed of a ketogenic lifestyle, you're at a serious energy source disadvantage. And if you spend long periods in the gym, you -are- going to burn through protein and muscle stores to make up for the fact that your fats simply can't keep up in a low carb but non keto lifestyle. -those- are the people I think are silly for expecting quick weight loss -and- gains. But for the big folks who are -very- big and reducing weight? Keep slowly increasing your weights as you lose fat, and you'll keep gaining lean muscle mass (admittedly, very slowly) as you reduce. Your lifts will increase probably commiserate with the speed of weightloss, until you hit a point where the amount of extra weight on the bar is no longer being countered by a loss of extra body fat. -That's- when you might get some flack from some of us if you are trying to lose weight but complaining about gains. Until then, have at em.
