Testosterone replacement therapy (TRT) in men with low testosterone has consistently shown to produce positive benefits with minimal side effects. Also, benefits of testosterone therapy can be both physical and mental. Restoring testosterone levels to within the normal range by using testosterone replacement therapy has shown to:
- Increase lean body mass
- Decrease fat mass
- Increase bone mineral density
- Improve sexual function
- Improve mood and well-being
Although some benefits appear in the first month of therapy, most effects begin to take place over the first few months. Learn more about these specific positive benefits of testosterone therapy below.
A Note on TRT
All these benefits have made testosterone replacement therapy usage increase substantially over the past several years. While TRT is usually well tolerated as long as testosterone is kept within normal, physiologic levels, side effects can occur. It is important for you and your physician to be aware of different administration methods and potential side effects.
Page Table of Contents
Increase in Lean Body Mass
Testosterone replacement therapy produces a moderate increase in lean body mass (muscle mass) in men with low testosterone.1-9 TRT users typically gain between three and six pounds of lean muscle mass in the first six months of treatment.
Why’s That Important?
As a man ages, he loses muscle mass, typically about 0.5 to 1.0% per year after the age of 40. This loss becomes progressively faster after the age of 40 and is worse if he has low testosterone.10 Muscle contributes a great deal to an individual’s resting metabolism. Therefore, losses in muscle slow down resting metabolism.
The increase in muscle mass brought about by testosterone therapy can be highly beneficial. It increases your lean body mass and thus raises your metabolism. The higher your resting metabolism, the more calories you burn at rest and the less likely you will be to put on any excess fat as you age.
Do not, however, worry about becoming muscle bound. TRT users typically gain between three and six pounds of lean muscle mass in the first six months of treatment.1-7 Once testosterone levels are stabilized within normal range, increases in muscle mass typically taper off. This stabilization usually occurs after about six months of treatment.
Expanded Detailed Explanation
In trials of TRT for elderly men, the benefits of testosterone on body composition (muscle mass and fat mass) and strength have been the most extensively studied area of research. Studies show that testosterone administered to men with low levels has a tendency to increase lean body mass.1-9 These results occur over a wide array of administration methods, including transdermal skin gels,3 scrotal patches,4 oral pills,5 and intramuscular injections.1,2,6,7 This increase in lean body mass is not surprising considering testosterone has muscle building effects, including protein synthesis, increasing muscle fiber cross-sectional area, and reducing muscle degradation.6
Decrease in Fat Mass
Testosterone therapy produces a moderate decrease in fat mass, especially abdominal fat mass, in elderly men with low testosterone.1,3-7,11-14 Typical fat loses range between five to ten pounds in the first six months of TRT treatment.
Why’s That Important?
As men age, they typically gains fat mass, especially abdominal (AKA visceral) fat. Besides giving you an undesirable gut, this increase in visceral fat increases the incidence of cardiovascular problems. TRT for men with low levels can keep you thinner and healthier since long-term studies consistently show a decrease in fat mass.
Expanded Detailed Explanation
In trials on TRT for elderly men, the effects on body composition and strength have been the most extensively studied area of research. Studies indicate that testosterone administration in men with low levels consistently decreases fat mass with rare exceptions. 1,3-7,11-15 A large number of studies have documented that abdominal obesity is associated with low total levels.16-19 Returning levels to normal physiological levels with TRT may reverse this fat deposition in the abdomen while simultaneously increasing muscle mass.
Increased Bone Mineral Density
Evidence shows that the benefits of testosterone therapy include the slowing or even reversing of the loss of bone mineral density due to decreased testosterone levels associated with aging.4,20-25
Why is Bone Mineral Density Important?
Osteoporosis and consequent fractures are NOT just a women’s health problem. This problem belongs to men just as it does to women. Hip fractures are not uncommon for men over the age of 65.23,24 Not only will a hip fracture or a fracture of another bone cause you to lose your functional independence, but it will also significantly increase your likelihood of death, particularly within one year of the fracture.7 One of the primary benefits of testosterone therapy is an increase in bone mineral density.
Expanded Detailed Explanation
Many studies indicate that one of the primary benefits of testosterone therapy is the prevention of bone loss.4,20-25 These studies showed an increase in bone mineral density at the lumbar spine compared to placebo controlled groups. One study reported no change in bone mineral density in the group receiving TRT but a small significant decline in bone mineral density in the placebo group.3 Thus, TRT resulted in an overall positive treatment. It also shows that, while TRT may not increase bone mineral density, it may slow and/or prevent decreases in bone mineral density typical of aging.
Improved Sexual Function
There are two essential elements of sexual function: tactile sensation (physical contact) and mental stimulation (thoughts and visual images as known as libido). When given to men with low testosterone, TRT increases sexual thoughts and sexual desire.26-28 So, testosterone benefits libido.
The benefits of testosterone therapy on physical sexual function are not conclusive. Erectile dysfunction can be related to one or more of many potential underlying medical conditions unrelated to testosterone levels. Thus, taking testosterone may not necessarily fix these unrelated underlying problems. Nevertheless, recent reviews on the effects of testosterone on erectile potency are encouraging.29-31 Also, in certain instances, testosterone used in conjunction with PDE-5 inhibitors (like Viagra) improves erectile function more than PDE-5 inhibitors alone.32-36
Improved Mood and Well-Being
Low testosterone is associated with behavioral changes that include decreased mood and well-being as well as depression. Due to the aforementioned association between low testosterone and decreased mood, it would make sense that testosterone benefits mood and well-being.
Some studies on the effect of testosterone therapy have shown testosterone benefits mood and overall quality of life as well as depression.4,22,37,38 Other studies have shown no benefit of TRT on these factors.3,15,39,40 Anecdotal evidence shows that many men do have an enhanced sense of well being from TRT. Nonetheless, these positive effects are not consistent and have yet to undergo rigorous scientific evaluation.
The Take Home Message
Testosterone replacement therapy is not a cure-all answer for mood disorders associated with low testosterone of aging. Depression is a serious problem. In fact, it is the most common psychiatric disorder in older men. If you are depressed, you are not alone. It is important to be aware that while TRT may help mood and well-being, it will not definitely cure your depression. Thus, if you think you may suffer from depression, talk to your physician or other medical professional.
External Resources: NCBI: Benefits of Testosterone Therapy
Updated: May 4, 2015
1. Page ST, Amory JK, Bowman FD, et al. Exogenous testosterone (T) alone or with finasteride increases physical performance, grip strength, and lean body mass in older men with low serum T. J Clin Endocrinol Metab. Mar 2005; 90 (3): 1502-1510.
2. Tenover JS. Effects of supplementation in the aging male. J Clin Endocrinol Metab. Oct 1992; 75 (4): 1092-1098.
3. Kenny AM, Prestwood KM, Gruman CA, Marcello KM, Raisz LG. Effects of transdermal testosterone on bone and muscle in older men with low bioavailable levels. J Gerontol A Biol Sci Med Sci. May 2001; 56 (5): M266-272.
4. Snyder PJ, Peachey H, Hannoush P, et al. Effect of treatment on bone mineral density in men over 65 years of age. J Clin Endocrinol Metab. Jun 1999; 84 (6): 1966-1972.
5. Wittert GA, Chapman IM, Haren MT, Mackintosh S, Coates P, Morley JE. Oral testosterone supplementation increases muscle and decreases fat mass in healthy elderly males with low-normal gonadal status. J Gerontol A Biol Sci Med Sci. Jul 2003; 58 (7): 618-625.
6. Ferrando AA, Sheffield-Moore M, Yeckel CW, et al. Testosterone administration to older men improves muscle function: molecular and physiological mechanisms. Am J Physiol Endocrinol Metab. Mar 2002; 282 (3): E601-607.
7. Blackman MR, Sorkin JD, Münzer T, et al. Growth hormone and sex steroid administration in healthy aged women and men: a randomized controlled trial. JAMA. Nov 2002; 288 (18): 2282-2292.
8. Frontera WR, Hughes VA, Fielding RA, Fiatarone MA, Evans WJ, Roubenoff R. Aging of skeletal muscle: a 12-yr longitudinal study. J Appl Physiol. Apr 2000; 88 (4): 1321-1326.
9. Sinha-Hikim I, Cornford M, Gaytan H, Lee ML, Bhasin S. Effects of supplementation on skeletal muscle fiber hypertrophy and satellite cells in community-dwelling older men. J Clin Endocrinol Metab. Aug 2006; 91 (8): 3024-3033.
10. Lambert CP, Evans WJ. Adaptations to aerobic and resistance exercise in the elderly. Rev Endocr Metab Disord. May 2005; 6 (2): 137-143.
11. Rebuffé-Scrive M, Mårin P, Björntorp P. Effect of testosterone on abdominal adipose tissue in men. Int J Obes. Nov 1991; 15 (11): 791-795.
12. Rolf C, von Eckardstein S, Koken U, Nieschlag E. Testosterone substitution of hypogonadal men prevents the age-dependent increases in body mass index, body fat and leptin seen in healthy ageing men: results of a cross-sectional study. Eur J Endocrinol. Apr 2002; 146 (4): 505-511.
13. Mårin P, Arver S. Androgens and abdominal obesity. Baillieres Clin Endocrinol Metab. Oct 1998; 12 (3): 441-451.
14. Mårin P, Odén B, Björntorp P. Assimilation and mobilization of triglycerides in subcutaneous abdominal and femoral adipose tissue in vivo in men: effects of androgens. J Clin Endocrinol Metab. Jan 1995; 80 (1): 239-243.
15. Sih R, Morley JE, Kaiser FE, Perry HM, Patrick P, Ross C. TRT in older hypogonadal men: a 12-month randomized controlled trial. J Clin Endocrinol Metab. Jun 1997; 82 (6): 1661-1667.
16. Seidell JC, Björntorp P, Sjöström L, Kvist H, Sannerstedt R. Visceral fat accumulation in men is positively associated with insulin, glucose, and C-peptide levels, but negatively with testosterone levels. Metabolism. Sep 1990; 39 (9): 897-901.
17. Khaw KT, Barrett-Connor E. Lower endogenous androgens predict central adiposity in men. Ann Epidemiol. Sep 1992; 2 (5): 675-682.
18. Després JP, Couillard C, Gagnon J, et al. Race, visceral adipose tissue, plasma lipids, and lipoprotein lipase activity in men and women: the Health, Risk Factors, Exercise Training, and Genetics (HERITAGE) family study. Arterioscler Thromb Vasc Biol. Aug 2000; 20 (8): 1932-1938.
19. Tchernof A, Labrie F, Bélanger A, et al. Relationships between endogenous steroid hormone, sex hormone-binding globulin and lipoprotein levels in men: contribution of visceral obesity, insulin levels and other metabolic variables. Atherosclerosis. Sep 1997; 133 (2): 235-244.
20. Reid IR, Wattie DJ, Evans MC, Stapleton JP. TRT in glucocorticoid-treated men. Arch Intern Med. Jun 1996; 156 (11): 1173-1177.
21. Amory JK, Watts NB, Easley KA, et al. Exogenous testosterone or testosterone with finasteride increases bone mineral density in older men with low serum levels. J Clin Endocrinol Metab. Feb 2004; 89 (2): 503-510.
22. Crawford BA, Liu PY, Kean MT, Bleasel JF, Handelsman DJ. Randomized placebo-controlled trial of androgen effects on muscle and bone in men requiring long-term systemic glucocorticoid treatment. J Clin Endocrinol Metab. Jul 2003; 88 (7): 3167-3176.
23. Bilezikian JP. Osteoporosis in men. J Clin Endocrinol Metab. Oct 1999; 84 (10): 3431-3434.
24. Orwoll ES, Klein RF. Osteoporosis in men. Endocr Rev. Feb 1995; 16 (1): 87-116.
25. Poór G, Atkinson EJ, Lewallen DG, O’Fallon WM, Melton LJ. Age-related hip fractures in men: clinical spectrum and short-term outcomes. Osteoporos Int. 1995; 5 (6): 419-426.
26. Davidson JM, Kwan M, Greenleaf WJ. Hormonal replacement and sexuality in men. Clin Endocrinol Metab. Nov 1982; 11 (3): 599-623.
27. Kwan M, Greenleaf WJ, Mann J, Crapo L, Davidson JM. The nature of androgen action on male sexuality: a combined laboratory-self-report study on hypogonadal men. J Clin Endocrinol Metab. Sep 1983; 57 (3): 557-562.
28. Skakkebaek NE, Bancroft J, Davidson DW, Warner P. Androgen replacement with oral testosterone undecanoate in hypogonadal men: a double blind controlled study. Clin Endocrinol (Oxf). Jan 1981; 14 (1): 49-61.
29. Jain P, Rademaker AW, McVary KT. Testosterone supplementation for erectile dysfunction: results of a meta-analysis. J Urol. Aug 2000; 164 (2): 371-375.
30. Morley JE, Kaiser FE, Perry HM, et al. Longitudinal changes in testosterone, luteinizing hormone, and follicle-stimulating hormone in healthy older men. Metabolism. Apr 1997; 46 (4): 410-413.
31. Gooren LJ, Saad F. Recent insights into androgen action on the anatomical and physiological substrate of penile erection. Asian J Androl. Jan 2006; 8 (1): 3-9.
32. Aversa A, Isidori AM, Spera G, Lenzi A, Fabbri A. Androgens improve cavernous vasodilation and response to sildenafil in patients with erectile dysfunction. Clin Endocrinol (Oxf). May 2003; 58 (5): 632-638.
33. Kalinchenko SY, Kozlov GI, Gontcharov NP, Katsiya GV. Oral testosterone undecanoate reverses erectile dysfunction associated with diabetes mellitus in patients failing on sildenafil citrate therapy alone. Aging Male. Jun 2003; 6 (2): 94-99.
34. Shabsigh R. Testosterone therapy in erectile dysfunction. Aging Male. Dec 2004; 7 (4): 312-318.
35. Chamness SL, Ricker DD, Crone JK, et al. The effect of androgen on nitric oxide synthase in the male reproductive tract of the rat. Fertil Steril. May 1995; 63 (5): 1101-1107.
36. Chou TM, Sudhir K, Hutchison SJ, et al. Testosterone induces dilation of canine coronary conductance and resistance arteries in vivo. Circulation. Nov 1996; 94 (10): 2614-2619.
37. Bakhshi V, Elliott M, Gentili A, Godschalk M, Mulligan T. Testosterone improves rehabilitation outcomes in ill older men. J Am Geriatr Soc. May 2000; 48 (5): 550-553.
38. English KM, Steeds RP, Jones TH, Diver MJ, Channer KS. Low-dose transdermal testosterone therapy improves angina threshold in men with chronic stable angina: A randomized, double-blind, placebo-controlled study. Circulation. Oct 2000; 102 (16): 1906-1911.
39. Janowsky JS, Chavez B, Orwoll E. Sex steroids modify working memory. J Cogn Neurosci. May 2000; 12 (3): 407-414.
40. Janowsky JS, Oviatt SK, Orwoll ES. Testosterone influences spatial cognition in older men. Behav Neurosci. Apr 1994; 108 (2): 325-332.
