How much weight do I need to lose to decrease at least one cup size after Breast Augmentation with 425cc/500cc HP Implants?

Thank you for your question.  Weight loss can decrease breast size but if the implants are too large for your body they may need eventually to be replaced.  I agree with your plan to lose 20 pounds if you can do that without damaging your health.  However if he still feel too large after the weight lost you may need smaller implants.

I am sorry you feel to big.  If you cannot get it resolved then Please find an experienced Board Certified Plastic Surgeon and member of the Aesthetic Society using the Smart Beauty Guide. These Plastic Surgeons can guide you on all aspects of facial surgery, breast augmentation and body procedures including tummy tucks or mommy makeovers!

Sizing for implant cases can be challenging, partially because patients don't always know exactly what they are looking for or have a hard time expressing it, and because bra sizes are nonuniform. Weight loss may reduce breast size slightly (perhaps a half-cup size per 20 lb body weight loss, probably not more than that), I think the bigger issue is whether you would be intending to lose weight if NOT for your implants feeling too big. If the answer is no, you are only considering losing weight to reduce breast size, then I suspect changing your implants to a smaller size is a better solution. A board certified plastic surgeon can assess you in the office and help address your concerns directly after a physical examination.