possible to gain back weight

Your pouch will never stretch to anything close to the size of your natural stomach, but you will still be able to eat enough that you can easily gain the weight back if you don't control what, and how much, you eat.  

I can eat enough, for example, that I could probably eat most of a Quarter Pounder with cheese or a Big Mac (if the center piece of bread was removed) and I discarded a bit of the bun.  That would be close to 500 calories (fully half of which is from fat!).  I only eat about 1400 calories in an entire day spread across 6 or 7 meals/snacks, so even though I have three meals that are a bit larger in terms of calories and the snacks are smaller, that would be about 200 calories per meal/snack.  So one fast food burger would be more than double the calories I can consume per meal without gaining weight. I also don't dump unless I eat A LOT of sugar, so I could easily get back into my pre-op habit of having half a cup of ice cream every night before bed. (With my favorite premium ice cream, that's 250 calories and 15g of fat.)

If people go back to grazing and/or drinking with meals and/or eating high fat, high calorie foods and/or eating a lot of slider foods (soft, slippery foods like ice cream or yogurt that don't stay in the pouch and therefore you can eat a lot of), it wold be easy to regain a significant amount of weight.

Of the roughly one dozen people I know IRL who have had either RNY (most of them) or DS (3), one RNYer gained all the weight back and then some, probably half of the RNYers have gained more than 25 pounds back (two of them more than 50 pounds back), and only one DSer has gained any significant amount of weight back (probably less than 25 pounds).  Statistically, someone is LEAST likely to regain with a DS because if the extreme amount of malabsorption.  You are also the MOST likely to have nutritional deficiencies with the DS for the same reason. I  don't personally know anyone with a sleeve, and both people that I knew who had the lap band did not even lose all the weight they needed to lose (let alone RE-gain it).

Lora