Yes, it's all about fiber recruitment. Muscle size has a lot to do with calorie intake. It's totally possible to increase strength at the same time one is losing weight - up to a point. Once one has full recruitment, increases will have to come from size increase, the desirability of which will depend on one's sporting goals. IME as long as one lifts several sets with the last rep to near failure, one will improve fiber recruitment, the number of reps desired depending on the strength/endurance balance desired. Rock climbers are perhaps one end of this continuum, up to say 50 reps increasing strength and endurance but not weight. I remember a RAAM winner some years ago being able to leg sled 500 lbs. for 50 reps. There's a goal for you. I've also seen pro body builders sledding enormous weights for 100+ reps. They eat a lot. Working to failure or one rep from failure is the trick, the latter being safer. That's been my practice for many years. I start over every fall, using 3 sets of 12. By summer, I've been using 2 sets of 5, also to near failure, once a week for maintenance - less stress in the gym, more stress on the road.