Will microdermabrasion and/or Retin-A help with loose skin?

Forget microdermabrasion, which is little more than "epidermabrasion," (its original name  a couple of decades ago), i.e. the kind of scaling and exfoliation that you can get from vigorously rubbing your skin with a Buff Puff, Loofah or even a stiff wash cloth. It really won't do much. Retin A can be helpful for maintaining skin (after several months of regular use and after you have received more appropriate therapy), but is unlikely to yield gratifying results as a monotherapy for the condition you describe. The crinkly, crepey skin that follows childbirth may be better, and much more quickly addressed with the use of "skin boosters"  fillers injected in a particular fashion, known as the "the body vectoring technique."  The latter may be accomplished via a fanning injection technique, a grid pattern technique or a combination of both, depending upon the particular  circumstances. In my Upper East Side Manhattan practice I typically opt for Belotero Balance or Restylane Silk for this indication. While some may recommend the use of fraxel lasers, radiofrequency and ultrasound treatments, I have not found the subtle, inconsistent and variable results often obtained with these methods sufficient to justify the time, expense, or discomfort (particularly with ultrasound) enough to recommend or justify their use. In my Israel satellite facility, where a far greater number of regulatory agency approved fillers are available, I typically select Restylane Skin Boosters and Teosyal Redensity II for this indication. For more information on this technique, check out the archives of RealSelf.com and be sure to seek consultation and treatment by a board certified aesthetic physician and not merely places hawking the supposedly "next best thing" devices for treating just about everything. Best of luck to you.

HiRetin A products are good for improving skin texture but can only do so much. You will see a definite improvement in the skins laxity but will need either Medical Needling or surgery to achieve satisfactory results.Hope this helps.

Microdermabrasion does not really do much and you can get the same from a dry washcloth.  Retin A is good for helping the appearance of fine lines and maintaining healthy skin but it sounds like the only way you are going to get the results you want is surgery. If interested see a board certified plastic surgeon