What is the best solution for a banana roll deformity?

Reducing your banana rolls, posterior upper thigh excess fat, if done properly and conservatively should give you improvement without making your buttocks drop.

I find that being to aggressive in the area of the leg below the buttock can result in a banana roll or a dip.  A combination of gentle contouring of the bulge with careful fat injections around the bulge to bring areas above and below the banana roll into the same level.  

The best treatment for this is VASER hi definition liposuction to tighten the area and fat transferred around it to lift the buttock and improve the fold.  Best, Dr. Emer.

Physical examination is necessary to see whether the banana role as a product of surplus fat or buckling of the skin. If that is the issue this areas susceptible to treatment. Skin buckling could be corrected with excision along the gluteal fold the most of the time the trade-off is not worth it.

Some banana rolls can be treated with liposuction, and some may need to tighten excess skin. Some laser liposuction is helpful in tightening skin. What you need specifically can be determined during the consultation. I would suggest meeting with a board certified plastic surgeon and discussing all your concerns. You do not have to just live with it.