Any athlete really knows this to be true. You don't lose weight running/lifting/biking, you lose it in the kitchen.
Multi-day hiking forces the issue as you have to carry the kitchen on your back.
Multi-day hiking forces the issue as you have to carry the kitchen on your back.
Sleep is also a commonly overlooked but incredibly important aspect. You could be busting your ass in the gym, have your diet on point, but not be making gains if you don't sleep or sleep poorly. For hypertrophy focused folks, muscle isn't built in the gym, it's built while you sleep - you tear it down in the gym so that it can rebuild during recovery.