I just had breast reduction and lift two days ago, and I have a lot of fluid retention?

Usually after any surgical procedure that is multiple hours requiring general anesthesia and IV fluids, there can be a few pound weight gain as well as "water retention".  As long as you are healthy, you will shed the water and pounds by a week or so.  If this does not happen then you should see your primary care doc.

There are several reasons this may happen which will all resolve over time. First, the anesthesiologist generally give you some IV fluid. Second, there is always some swelling of the breasts immediately after surgery. Third, the pain medication may make you constipated, causing you to retain more abdominal weight. Four, you are also less active after surgery, therefore burning fewer calories. Altogether, once all these resolve, you will be right on track and if you haven't overeaten while recovering, you should weigh slightly less than you did prior to surgery.

Undoubtedly excess weight is related to fluid retention. You get a lot of IV fluids that the anesthesiologist gives you and it's not unusual to have swelling throughout your body. Usually the fluid will start to go away on day three of four. It will get better, be patient