The photo shows increased buttock/thigh fullness with a pronounced lower gluteal crease and some contour transition near the upper thigh. After a 30 lb weight gain, this can come from fat distribution, skin laxity, cellulite/tethering, posture, or the way the lower buttock and posterior thigh meet. An in-person exam is needed to tell which is the main cause. A BBL can improve shape by adding fat to selected areas and sometimes combining liposuction of the waist/flanks/thighs for better balance, but it does not reliably fix loose skin, cellulite, or a fold caused by skin laxity. If your weight is still changing, I would first stabilize your weight for several months, because further gain or loss can change the result. Depending on the exam, options may include weight management, targeted liposuction, fat grafting for shape, skin tightening for mild laxity, or a lift procedure if there is significant loose skin. If you consider BBL, choose a board-certified plastic surgeon who follows current safety standards, including fat placement only in the subcutaneous layer.