weight loss post op

Obesity is also hormonal, as well as calorie-based.  Your body is readjusting.  Also, for months there is swelling, water retention, med changes, etc.  It takes months, not weeks, to recover from abdominal surgery.  The body is also fighting to retain nutrition to heal.  It requires a tremendous amount of resources.

We lose weight during the pre-op diet because we are shedding glycogen due to the severely low carb nature of the diet.  Glycogen is the stored form of glucose.  We store it in muscles and our liver - 1 gram of glycogen for 3 grams of water.  Maybe?  I don't remember the ratio.  Anyway!  This means that a crapload of that weight is, literally, water.  That is why we lose it rapidly.  The body is burning through glycogen because it is going "holy crap where is our glucose?!" The body then reverts to burning fat.  The 5 pounds you lost are all fat.  The weight pre-op was likely 80% water.  That's where the "liver shrinking" comes from.  A VLC or ketogenic diet would accomplish the same effect.

Reasons weight loss is slow too is many people eat stuff like refried beans early on (carbs cause slow weight loss because insulin triggers fat storage), and don't hydrate as much, etc, etc.  Normally it's a global set of small things.

5 pounds in two weeks is a lot of weight to lose.  You've lost 2/3 of a gallon of milk worth of mass. :) No small feat for the body.

I had no stalls until 12-13 months out when my hubris/bad habits caused it.  However, I was very cautious with intake and also stayed in liquids longer due to Harvey-the-sleeve rebelling slightly