Hi Periwinkle,
I would think it depends on the cause of the excess weight, although by balancing the body with Reflexology all conditions could be helped.
Relaxation would help to eliminate stress and reduce stress-induced eating and could stimulate the bodies own weight-reducing elements, such as the brown adipose tissue, into action. Other conditions such as thyroid disorders, PCOS, etc. which can themselves cause great weight gain might also derive benefit from Reflexology in conjunction with standard Medical practices and result in weight loss.
I will be very interested to read the other replies to your question.