How do you know when you need a back bra lift and not just lipo of the entire back?

Great question.  Usually you need this type of procedure when you have lost weight and have more skin than fat.  I recommend that you sit down with a board certified plastic surgeon for a consultation to assess the areas of concern.  Good luck

Great question.  I see a lot of patients who are concerned about excess "fat" in the braline area but on examination, there not much subcutaneous fat there and the problem is due mostly to loose skin.  I see this even in slender, fit patients.  Even if you can pinch a generous amount of fat, removing it with liposuction alone may not give you a smooth back unless your skin is very elastic and taut.  Your skin elasticity would need to be assessed in person.  A braline back lift will remove the excess skin and liposuction is sometimes done with it.  I recommend seeing a few board certified plastic surgeons in your area to better be able to direct you.  Good luck.