As of right now, I've been running anavar at 30mg a day for 36 days
Anabolic steroids will also offset the catabolic effects of T3, but by a different mechanism Here is a link to a study I posted a while back about the combined effects of T3 and testosterone:
http://jcem.endojournals.org/cgi/content/full/84/1/207
They took two groups of men, gave one group 50 mcg/day of T3, and the other group got the same 50 mcg plus testosterone enanthate, 200mg/week. They were required to lie in bed for 28 days!
At the end of that period, the T3 group lost an average of 8.6lb, while the T3 + test group lost 2.2lb. Lean body mass in the T3 group declined by 3.3lb while the lean body mass of the T3 + test group increased by 4.4 lbs.
This is lying in bed on only 200mg/week of test, and probably on a poor (by bodybuilding standards) diet.
The group that carried out the insulin and T3 study also carried out another study, Adonis, (albeit again on just six people) under different conditions and arrived at the same conclusion: T3 increases the ability of insulin to inhibit proteolysis. They think this is an adaptive mechanism to reduce muscle wasting in hyperthyroidism:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7573427&dopt=Abstract
People also seem to adapt to T3 administration in that their nitrogen balance becomes less negative over time. See (1) and figure 2 in the paper linked to above:
http://jcem.endojournals.org/cgi/content/full/84/1/207
The group that carried out this and similar studies did not address the mechanism for this. Maybe it is the insulin effect described above.
(1) J Clin Endocrinol Metab 1997 Mar;82(3):765-70
A paradigm of experimentally induced mild hyperthyroidism: effects on nitrogen balance, body composition, and energy expenditure in healthy young men.
Lovejoy JC, Smith SR, Bray GA, DeLany JP, Rood JC, Gouvier D, Windhauser M, Ryan DH, Macchiavelli R, Tulley R.