You may want to look in to Anavar. I have heard of people taking this with muscle wasting disorders and having great success. If you have seen the movie Bigger, Stronger, Faster there is an HIV patient who was very skinny/weak due to the disease and after taking anavar he was able to put on a good bit of healthy weight and lean body mass. Anavar will help preserve lean mass against catabolism, even at a caloric deficit.
Check out pubmed . com
http://www.ncbi.nlm.nih.gov/pubmed/16540931 Found this in about 2 minutes. It is not 100% conclusive as both parties gained weight, but its a good read and a good start. It also mentions taking testosterone due to shutdown from the Anavar (Oxandrolone)
"CONCLUSION:
Oxandrolone administration is effective in promoting dose-dependent gains in body weight and BCM in HIV-infected men with weight loss."
It's a good place to start researching and they are medically recognized studies.
I started researching this for my uncle who had ALS, unfortunately the doctor's wouldn't listen. Best of luck