For example, the study published in Obesity Research tells that the scientists measured testosterone levels in two groups of middle-aged men with obesity. One group underwent a 16-week weight loss program, while the second group did nothing. Each participant of the first group lost 20 kg on the average. And these participants experienced a significant increase in testosterone levels. So, the fight against overweight is very important for those who want to overcome testosterone deficiency. But starvation is strictly forbidden because this is a stressful situation which leads to the sharp decline in T levels.

There is an increased incidence of hypogonadism in men with rheumatoid arthritis. Tengstrand et al (2002) studied hormonal levels in 104 men with rheumatoid arthritis and 99 age-matched healthy men. They divided their subjects into 3 age groups: 30–49, 40–59, 60–69. Mean non-sex hormone binding globulin-bound testosterone (bioavailable testosterone) was lower in men with rheumatoid arthritis for each of the three groups. LH was also found to be lower in the patients with rheumatoid arthritis suggesting a hypothalamic-pituitary cause of the reduced bioavailable testosterone. Of the 104 men with rheumatoid arthritis, 33 had hypogonadism compared to 7 of the 99 healthy controls.

The effects of testosterone in humans and other vertebrates occur by way of multiple mechanisms: by activation of the androgen receptor (directly or as DHT), and by conversion to estradiol and activation of certain estrogen receptors.[109][110] Androgens such as testosterone have also been found to bind to and activate membrane androgen receptors.[111][112][113]

Sharma, R., Oni, O. A., Gupta, K., Chen, G., Sharma, M., Dawn, B., … & Barua, R. S. (2015, August 6). Normalization of testosterone level is associated with reduced incidence of myocardial infarction. European Heart Journal, 36(40), 2706-2715. Retrieved from