It is well-documented that testosterone levels decline with age in men. After the age of 40 years, total T decreases on average -4 ng/dL ( -0.124 nmol/L) per year [1] or 1.6% per year [2], and bioavailable T  by -2 to 3% per year. [2] In older men (over 60 years of age), the average decline in total testosterone levels has been found to be 110 ng/dL every decade.[3]

However, the relative contributions of changes in health and lifestyle to that decline have not been adequately evaluated. A notable study was set out to investigate this…


The objective of this study was to establish the relative importance of aging, health, and lifestyle in contributing to the testosterone decline in aging men.[4]

A prospective cohort study of health and endocrine functioning in randomly selected men with a baseline visit (T1, 1987-1989) and two follow-up visits (T2, 1995-1997; T3, 2002-2004) was conducted.

An observational study of men residing in greater Boston, Massachusetts, was conducted.

Participants included 1667 men aged 40 – 70 at baseline; follow-up was conducted on 947 (57%) and 584 (35%) at T2 and T3, respectively.

There were substantial declines in total serum T and FT levels associated with aging alone. However, many health and lifestyle changes were associated with accelerated decline.

When not taking health status into consideration, declines of -14.5% (range -16.3% to -12.6%) in total T and -27.0% (range -29.1% to -5.0%) free T per decade of aging.

The corresponding estimated trends including only subjects who were apparently healthy were less sharp; among such subjects, declines of -10.5% (range -14.0% to  -7.0%) in total testosterone and -22.8% (range -26.9% to -18.7%) in free testosterone per decade of aging.

A 4- 5 kg/m2 increase in body mass index (BMI), for example a man 5’8 (1.75 m) gaining weight from 176 lb (80kg, BMI 26) to 202 lb (92 kg, BMI 30), was associated with a decline in total testosterone level comparable to that associated with approximately 10 years of aging.


This study[4], and many others [5-8], show that both chronological aging and changes in health and lifestyle factors are associated with declines in serum T. Co-morbidities and lifestyle influences may be as strongly associated with declining testosterone levels as is aging itself.

Another study confirmed these finding by showing that the effect of increasing body fat and waist size on lowering testosterone levels is more substantial, compared with that of age. [5] This later study also demonstrated that body fat/waist size is the most important determinant of the differences seen in total testosterone levels [5], regardless of age. [9] Accumulating research data underscores the major impact of body fat/waist size in determining testosterone levels.[10]

The sharper decline in both testosterone levels in people with poor health, among whom obesity, metabolic syndrome, diabetes and cardiovascular disease is common, indicates that a substantial proportion of the apparent aging effect is attributable to changes in health status. Thus, the age-related testosterone decline can be partially prevented and/or slowed down by adherence to a healthy lifestyle incorporating a sound diet and regular exercise.

1.            Harman, S.M., et al., Longitudinal effects of aging on serum total and free testosterone levels in healthy men. Baltimore Longitudinal Study of Aging. J Clin Endocrinol Metab, 2001. 86(2): p. 724-31.
2.            Feldman, H.A., et al., Age trends in the level of serum testosterone and other hormones in middle-aged men: longitudinal results from the Massachusetts male aging study. J Clin Endocrinol Metab, 2002. 87(2): p. 589-98.
3.            Morley, J.E., et al., Longitudinal changes in testosterone, luteinizing hormone, and follicle-stimulating hormone in healthy older men. Metabolism, 1997. 46(4): p. 410-3.
4.            Travison, T.G., et al., The relative contributions of aging, health, and lifestyle factors to serum testosterone decline in men. J Clin Endocrinol Metab, 2007. 92(2): p. 549-55.
5.            Wu, F.C., et al., Hypothalamic-pituitary-testicular axis disruptions in older men are differentially linked to age and modifiable risk factors: the European Male Aging Study. J Clin Endocrinol Metab, 2008. 93(7): p. 2737-45.
6.            Yeap, B.B., et al., Healthier lifestyle predicts higher circulating testosterone in older men: the Health In Men Study. Clin Endocrinol (Oxf), 2009. 70(3): p. 455-63.
7.            Camacho, E.M., et al., Age-associated changes in hypothalamic-pituitary-testicular function in middle-aged and older men are modified by weight change and lifestyle factors: longitudinal results from the European Male Ageing Study. Eur J Endocrinol, 2013. 168(3): p. 445-55.
8.            Haring, R., et al., Clinical correlates of sex steroids and gonadotropins in men over the late adulthood: the Framingham Heart Study. Int J Androl, 2012. 35(6): p. 775-82.
9.            Goncharov, N.P., et al., Testosterone and obesity in men under the age of 40 years. Andrologia, 2009. 41(2): p. 76-83.
10.          Corona, G., et al., Body weight loss reverts obesity-associated hypogonadotropic hypogonadism: a systematic review and meta-analysis. Eur J Endocrinol, 2013. 168(6): p. 829-43.

  1. Peter K 10 years ago

    Thank you for the article and greatly appreciate your research and writings on this topic. The suggested T levels span all ages and I feel that there should be age based levels. There is so much to say on this topic. My opinion based on personal experience is that diet, lifestyle, and exercise alone will not sufficiently reverse low T. These factors will help, but if someone is at a low level relative to age, a managed TRT program is the only course of action – combined with a healthy lifestyle, a well balanced workout plan, and a healthy diet. I would hope to see more studies on the long term affects of well managed TRT as well as differentiation on the types, frequency, and methods of administration. There is much to learn on this topic and I have found the books by Nelson Vergel, and Jeffry Life interesting as well. More clinical research and data is needed. Thanks again for your research and looking forward to your future writings on this topic

    • Monica Mollica 10 years ago

      Yes, the topic of TRT is indeed large. An important point about TRT as is related to age and lifestyle is the bidirectionality of the effects. For example, elevated body fat mass can cause low-T, and low-T can cause increased body fat accumulation. I will cover this in upcoming articles.
      Like you said, while a healthy lifestyle can reduce the age-induced T decline, T will still decline with age, albeit less in men who adhere to a healthy lifestyle. However, like you point out, a man can be lean and still have sub optimal T levels. What is the optimal T level is a topic that is generating a lot of discussion among researchers and health professionals, and there is no unanimous recommended T threshold or range. The optimal T levels thus has to be set for each man individually, taking into consideration other parameters like symptoms, muscle/bone/fat mass, blood lipids, metabolic parameters (blood glucose, insulin resistance)hemoglobin etc. There are indications that each androgen dependent effect has its own optimal T level.
      Also, there are individual differences in androgen receptor sensitivity, steroid metabolizing enzyme activities etc, which makes it unlikely that there is one single optimal level across the board.
      In a previous article I outlined two 5-year long studies:
      …and more long-term studies are underway…
      The topic of different testosterone formulations and dosing/duration of treatment is another important aspect of TRT.
      I will cover all these issues, and outline the most recent research in the area, in upcoming articles and in my book on TRT that I am in the process of writing. Stay tuned! 🙂

      • Iggy 10 years ago

        I look forward to your new posts!

  2. Chris Ball 10 years ago

    Geezus Will, where have you been? We’ve missed you…
    Great content and excellent insight. Keep the info flowing!

    • Will Brink 10 years ago

      I didn’t write this article Chris (unless you think I had a sex change and become a pretty muscular blond woman…), but I’m around bro! 🙂
      Hope all is well on your end.

  3. Sean 10 years ago

    Another great article by Monica, as us Aussies would say “she is a chick that knows her s#it”

  4. Cal 10 years ago

    Great article. All of your research is well documented. Keep up the good work. I’d like to see an article on aromatase inhibitors. I’m on TRT and found that I’m very good at converting T to E.

    • Monica Mollica 10 years ago

      When it comes to estradiol (the main estrogen) and men; both too low and too high levels can be deleterious.
      So if your estradiol level is too high, taking an aromatase inhibitor might be a good idea. Just remember that men need a little estradiol in the same way that women need a little testosterone, so don’t completely shut down your aromatase.

      • Marko 10 years ago

        Great article again 🙂 Looking forward to new articles 🙂
        Can you tell me the best (light) aromatase inhibitors when on trt ? Is zinc alone ok ? Or I need arimidex or similar ? Thanks

        • Monica Mollica 10 years ago

          Which aromatase inhibitor that is best for you is something you and your doctor will have to figure out. There are no nutrients that work for this.

  5. Kent Ingram 10 years ago

    I would also add sleep apnea to the list of T-killers, whether it’s adult onset or lifelong (since childhood). Treatment doesn’t seem to improve things a whole lot, but that’s an individual thing, I’m sure. At any rate, aging is bad enough but sleep apnea just adds to the misery and is like getting a double-whammy.

    • Monica Mollica 10 years ago

      Low total testosterone levels are associated with less healthy sleep in older men:
      The association of testosterone levels with overall sleep quality, sleep architecture, and sleep-disordered breathing. Barrett-Connor E, Dam TT, Stone K, Harrison SL, Redline S, Orwoll E; Osteoporotic Fractures in Men Study Group. J Clin Endocrinol Metab. 2008 Jul;93(7):2602-9.
      If you have tried TRT and didn’t feel any sleep improvement, maybe you didn’t raise your level high enough.

      • Kent Ingram 10 years ago

        I have yet to get myself tested because of a lack of health insurance, but that is changing. Sleep apnea has plagued me since childhood and I’ve been under CPAP therapy for the last 12 years. However, you have to be tested every couple of years in a sleep lab, to see if you need adjustments to the equipment and replacement of worn equipment, after a length of time. The cost of a sleep lab test, out of pocket, is $1,100.00. New CPAP equipment can run up to nearly the same amount. I did my own research, some years ago, and found the link with sleep apnea and Low-T. Hopefully, a lot of this misery can be mitigated, soon. Thanks for the reply, Monica.

Leave a reply

Your email address will not be published. Required fields are marked *


This site uses Akismet to reduce spam. Learn how your comment data is processed.



I'm not around right now. But you can send me an email and I'll get back to you soon.


Log in with your credentials

Forgot your details?