The cost of the procedure may vary depending on how long it takes
The cost may not necessarily be more because of increased weight, but because of the time involved to complete the procedure.
The time to complete the abdominoplasty may take longer in heavier patients.
There are in general 4 components to the cost of a surgical procedure: Operating Room, Anesthesia, supplies(garments, implants etc), and the professional fee by the surgeon. Many operating rooms and anesthesiologists charge based on time.