Up till recently, prednisone has been thought to be about 5x stronger than hydrocortisone, when used for treatment of CAH.  But, a recent study out of Canada has concluded that it may actually be 10-15 times stronger than hydrocortisone.  In other words, much less prednisone might be needed than previously believed. 

Here is the abstract of this article on Pub-Med. I used to have a full length copy , but it’s been a while since I’ve looked for it, so I’m not sure how quickly I can put my hands on it.  It talks more specifically about growth suppression, rather than weight gain, as a side effect of too high of a dose...but, both are well known side effects of oversuppression, so I think it’s fair to say what applies to growth suppression, also applies to uncontrollable weight gain.  

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http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=14517528

1: J Pediatr. 2003 Sep;143(3):402-5. Related Articles, Links 

 
Prednisolone in the treatment of adrenal insufficiency: a re-evaluation of relative potency.

Punthakee Z, Legault L, Polychronakos C.

Endocrinology and Metabolism, Montreal Children’s Hospital, McGill University Health Centre, Montreal, Quebec, Canada.

Prednisolone has unknown growth-suppressing effects relative to other steroids. We retrospectively studied 9 children (6 with congenital adrenal hyperplasia, CAH) receiving hydrocortisone replacement after switching to prednisolone (dose ratio, 1:5). Growth velocity and, in patients with CAH, 17-OHP decreased significantly. Dose reduction reversed these effects. Roughly, growth suppression relative potency for prednisolone:hydrocortisone was 15:1.

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Sooooo.....if we were to go back and evaluate your pred dose, Ash:

At 5’-2" and 175#, your BSA is currently 1.86 m2.  If we assume that the old  pred:hc relative potency of 5:1 is correct, then the dose does not appear to be too high....about the equiv. of 13.5 mg/m2 of hc/day.   But, if we are to believe the new research, then in fact, it could be more equivalent to ~26.88-40 mg/m2 if hc/day....a very high dose, indeed.  If we were to put you at a healthier weight, your BSA would go down some, making these relative doses even higher.

It is not my place or intention to tell you what the right dose for you, but if you were to ask if there is ANY reason to believe that a too high dose of medication could be part of the problem here, I would have to say, "Absolutely!"  Bottom line, you are having a lot of problems doing things the way you have been doing, so---in my opinion---it is not at all unreasonalbe to want to try soemthing new.  I just don’t think that what you should try first is giving up your medication altogether.

Please feel free to email me if you would like to chat further.