This is utter rubbish. The natural age-related fall in T levels is only a few tenths of a percent per year. Healthy men tend to retain good T levels well into old age.
J Clin Endocrin Metab.doi:10.1210/jc.2012-3842 Longitudinal changes in testosterone over five years in community-dwelling men
(abstract at end)
However for many other reasons, T levels can dramatically fall. Some of these reasons in include medications, stress, various diseases.
A common example is men who are on cortico-steroid medication for inflammatory or auto-immune conditions. Cortisol reduces T levels, reduces its effectiveness, and operates in the opposite manner (ie catabolic versus anabolic).
Longitudinal changes in testosterone over five years
in community-dwelling men
Zumin Shi 1 *,MD, PhD, Andre B. Araujo 2 ,PhD, Sean Martin 1 ,
Peter O’Loughlin 3 ,MD, PhD, and Gary A. Wittert 1 ,MD, FRACP
1
Discipline of Medicine, University of Adelaide, S Australia; 2 Epidemiology, New England Research
Institutes, Inc., 9 Galen St, Watertown, MA 02472, United States; 3 Institute of Medical and Veterinary
Science Pathology, Adelaide, S Australia
Context. There are few population-based studies reporting longitudinal changes in total tes-
tosterone (T), luteinizing hormone (LH), follicle stimulating hormone (FSH), and sex hormone
binding globulin (SHBG) levels, and limited information on risk factors for their change.
Objective. The objective of the study was to examined 5-year changes in serum T, LH, FSH, and
SHBG levels among Australian men.
Design. A randomly selected, community based cohort of 1,588 men age 35 or older at recruit-
ment (mean age 54؎11y), with available data at two visits. Men on medications known to affect,
or with established pathology of, the hypothalamo-pituitary gonadal axis were excluded, leav-
ing 1,382 for analysis.
Results. Mean baseline and follow-up T levels were 16.2؎1.4nmol/L and 15.6؎1.4nmol/L; a
change of -0.13nmol/L/y. Annualized T changes were associated with being unmarried, obesity,
and smoking at baseline, but not diabetes, hypertension, or cardiovascular disease. T declined
in men with persistent depression, or who developed chronic disease, and increased in men who
were married, as compared to unmarried, at both time points. In the multivariate analysis,
smoking cessation, development of central (waist >100cm) or generalised (BMI > 30) obesity
resulted in T decreases of 0.36, 0.25, and 0.20nmol/L/y respectively. Quitting smoking, developing
obesity, and having persisting depression were inversely related to SHBG change.
Conclusions. An age-related decline in T levels is not inevitable but largely explained by smoking
behaviour and intercurrent changes in health status, particularly obesity and depression."