ohashi said:
I never understood how people manage to lose muscle with T3. There must be another factor at play here that I do not understand
There is a rationale behind it: synthetically induced hyperthyroidism has been shown to:
1)increase SHBG levels
2)decrease free Testosterone levels
3)elevate estradiol and progesterone serum concentrations
4)higher rates of androgen:estrogen conversion
5)decreased insulin secretion
^^not an anabolic environment if you're 'natural', eh?
Chopra IJ, Tulchinsky D. Status of estrogen-androgen balance in hyperthyroid men with Graves' disease. J Clin Endocrinol Metab. 1974 Feb;38(2):269-77.
Ridgway EC, Maloof F, Longcope C. Androgen and oestrogen dynamics in hyperthyroidism. J Endocrinol. 1982 Oct;95(1):105-15
Lovejoy JC, Smith SR, Bray GA, Veldhuis JD, Rood JC, Tulley R. Effects of experimentally induced mild hyperthyroidism on growth hormone and insulin secretion and sex steroid levels in healthy young men. Metabolism. 1997 Dec;46(12):1424-8
Loric S, Duron F, Guechot J, Aubert P, Giboudeau J. Testosterone and its binding in hyperthyroid women before and under antithyroid drug therapy. Acta Endocrinol (Copenh). 1989 Sep;121(3):443-6.
Southren AL, Olivo J, Gordon GG, Vittek J, Brener J, Rafii F. The conversion of androgens to estrogens in hyperthyroidism. J Clin Endocrinol Metab. 1974 Feb;38(2):207-14.
On top of that:
1)increased oxidative energy metabolism (calorie deficit would further skew homeostasis)
2)increased Na/K/Ca ATPase which would be a sign of increased metabolism but in calorie deficit (cutting - that's what T3 is for ain't it) maintaining these substrates is virtually impossible which leads to cell death
3)increased heart work - heart want more energy/ATP
Clin Endocrinol (Oxf) 1980 Nov;13(5):489-506 Metabolic aspects of the calorigenic effect of thyroid hormone in mammals. Sestoft L.
Annu Rev Nutr 1995;15:263-91 Thermogenesis and thyroid function. Freake HC, Oppenheimer JH
Clin Endocrinol (Oxf) 1980 Nov;13(5):489-506 Metabolic aspects of the calorigenic effect of thyroid hormone in mammals. Sestoft L.
Endocrinology 2002 Feb;143(2):504-10 Are the effects of T3 on resting metabolic rate in euthyroid rats entirely caused by T3 itself? Moreno M, Lombardi A, Beneduce L, Silvestri E, Pinna G, Goglia F, Lanni A
Concomittant administration of androgens is recommended but could be avoided by maintaing proper nutrition level and supplementing with 'stuff'