After Getting a Breast Lift, How Much Weight Can I Loose and Still Maintain the Surgery Results?

I would concur that anything above 20 lbs tends to affect the results in a detrimental fashion.  This has some variability as a 20 lb weight loss in a 220 lb woman may have less of an effect than a 20 lb weight loss in a 120 lb woman.

I would encourage you to loose weight before the procedure.  The shape of your breasts after a mastopexy may change significantly after weight loss.   You may even need to consider the use of implants depending on how much weight you are considering loosing.

weight loss can significantly affect breast size , shape and contour in some women.

your past experience with weight changes and your own breasts is the best indicator

There is not defined weight loss that will determine if the breasts deflate it is a combination fo factors including your fat/breast tissue ratio of the breast.  If I had to guess, I would say that if you lost 15-20 pounds or more, it may impact your overall breast shape.

The answer to this question depends entirely on your body habitus and amount of breast fat present. Typically, the nipple position stays the same, but the breast tends to "deflate" with significant weight loss. This can lead to a flat, wide appearing breast. Unfortunately, without photos or an exam, it is impossible to give you any more specific information.