shot gut/rapid transit/weight gain

I am so sorry that your son is going through this.
No real answer for you, or at least not directly. It all depends on how much gut they had to remove. Not having a colon is not enough to create short-gut syndrom...most of us on this site lost theirs years ago and have no long term problems. People with pouches tend to have their pouches slowly adopt some of the functions of their colon and start to absorb fluids and certain nutrients through the pouch...But that takes some adaptation time. It took me years to start putting on weight but once I did it just wouldn't stop. I have had my K pouch (same pouch, just a different exit strategy) for 34yrs and have needed a few revisions that cost me guts...and I came back from it without any problems...that said, I do use suppliments religiously (chewable multi-vits, liquid Vit Bs, various other minerals etc) plus when I am very active I can add protien powders or other things.
I haven't been following your post enough but am curious about his age and how recent the surgery is? Guys (most of them) tend to burn calories faster, have higher metabolisms (sigh) and remain thinner longer. Then there is thyroid function, heridity etc which are serious considerations.
You need to give it time, sometimes a few years...keep his nutrition up, make sure that he isn't suffering from deficiencies and doesn't get dehydrated...the rest will come in time.
Sharon

Thanks - this is interesting for me to hear that there is still improvement years out. My son is 13 and had his surgery in April - so he is 9 months out. He has developed Crohns (takes humira and methotextrate) still seems antibiotic dependent - so is taking augmentin or cipro all the time and has started a pretty restricted diet which has cut down his frequency but things still move through him quickly and weight gain not happening.
Just wondering about this concept of "functional short bowel" ....
Which protein powders do you use? Thanks.

A friend of mine with a Koch pouch has a short bowel. He has had this for over 20 years and has no problem with diet or nutrition. In fact, he gains weight too easily.

Had a discussion about short bowel syndrome - just yesterday with my surgeon
My small intestine has 2 metres of functional bowel (2 metres up to ileostomy, 40 cms none functioning beyond that)
I had read on the internet that small intestine was around 7 metres long - and wanted to know why mine was only 2 metres long(I have not lost any small bowel, other than a small amount to make j pouch that is not functioning)
I have a high out put stoma, but as my haemoglobin levels are increasing and blood tests are fairly normal - then I don't have short bowel syndrome - he said. He suggested it might be a problem in someone with a small intestine 1 metre or less in length