I have a pair of MBT tennis shoes and really like them. However, I only got them because of foot pain and problems, not for any fitness benefits. I have not noticed any changes in muscle tone and have definitely not lost any weight, but they are comfortable for my feet--though not a cure. I have been plague by plantar fasciitis, and have had cortisone shots, taping, and custom orthotics despite the shoes. Hopefully I can get it taken care of, and the shoes will help with "maintenance." I would like to get a pair of their sandals too since they are pretty comfy (but expensive, about $250 a pair). Great shoes, but I really can't recommend them for providing fitness or weight assistance.