This problem usually occurs because one object has different scale parameters than another, like when you create, and revolve a curve. The revolved surface and curve scale differently because of their different parameters.
One thing you could try is freezing the transformations which should make the parameters equal, or you can create a group, which should make all your body parts have equal parameters.
Then u can ungroup when youre done scaling.
"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man."
George Bernard Shaw - Man and Superman