You didn't specify what aircraft or any details, but fuel loading by tank concerns not only aircraft control but wing bending moment. Fuel load may be attached to structural and operational limitations, such as being limited to certain speed ranges at certain altitudes, at certain fuel states or with certain tanks filled or not filled. One may be required to maintain a greater fuel difference outboard than in, in some aircraft, for wing bending moment purposes. Some of these restrictions won't necessarily affect aircraft control, but will affect the stresses places on the airframe (specifically the spar, and associated load-bearing structure).