Tone Matters
While my experience is limited, I think muscle tone DOES matter. I have always had a low body fat percentage and always been ticklish, so I admit I do not have a comparison point.
But I agree with what others have said, on hard digging tickling, fat deposits would afford some protection. Toned muscle can be accessed more easily.
The dudes who used to tickle the crap out of me in wrestling favored "claw" tickling, digging their fingers under muscles, like the edge of a pec, or edges of abdominals and dig under. Went ballistic trying to get away, sort of an almost painful tickliing if you keep it up too long.
I dont see what difference tone will make on the soft tickling though.
Another thought, the person tickling may tickle more if they like the visual of how your leaner body responds to tickling. If they like the desperate flex of your bod, they may just go to town. Then again, lers usually don't need a lot of encouragement.
Then again, most of my tickling was with sadistic wrestling buddies, have not got to experience a true female ler yet. So I guess my soft tickling experiences are mostly yet to come, I hope.