We have talked a lot about how overweight/obesity leads to Type 2 Diabetes, but there is another very important clinical manifestation of overweight/obesity that is probably not talked about as much as it should: sex hormones. Excess adiposity has the potential to disrupt the normal physiology of sex hormones in both women and men, and this can lead to significant quality of life issues in the present as well as health complications for the future. In women, it causes Polycystic Ovarian Syndrome, a common cause of sub fertility and infertility, and in men, overweight/obesity can cause Male Obesity Secondary Hypogonadism (MOSH). This is a low or lowered testosterone level associated with
overweight/obesity. While there are many clinics, online and otherwise, that will simply provide testosterone replacement therapy, the results of this approach alone are disappointing for some men and may be missing the bigger picture as well. Let’s look a little closer at the underlying causes today of lowered testosterone levels in men and how it relates to the increase in overweight/obesity. There may be a better way, or at least another way or a more complete way.
Overweight and moderate obesity lower free testosterone levels by increasing sex hormone binding globulin levels (SHBG) binds to testosterone, making it inactive. So, increasing the amount that is bound and inactive can lead to a normal total testosterone level (which is what is usually measured) but a low physiologically active level. With more marked obesity, total testosterone decreases due to decreased stimulation for its production from the brain in the form of lowered leutenizing and follicle stimulating hormone levels. This may also be when fertility is reduced. What causes this? Recall the blog on how excess fat tissue is hormonally and metabolically active? In the inflamed, insulin resistant state, adipose tissue expresses the enzyme aromatase, which turns testosterone into a form of estrogen known as estradiol. This hormone then also feeds back to the pituitary to reduce the hormone to stimulate sex hormone production, causing a “double whammy” of lowering testosterone and then turning off the signal to produce more, while increasing estradiol, the female hormone. How can you tell if this is happening to you? A man’s waist circumference is a better predictor of testosterone level than BMI. If your waist is large compared to your chest and shoulders, this may be playing a role. You may be able to see some signs by looking to see if your body proportions have changed, even without any blood work.
Which comes first, the chicken or the egg, or the obesity or the low-testosterone? Like insulin resistance and adipose, the answer is probably that it is a cycle. Once you reach a certain “tipping point”, normal physiology is disrupted, and that disruption leads to more disruption. In other words, once you start to get mildly overweight, the sex hormone binding globulin increases, binding up a larger portion of testosterone than normal and rendering it inactive. One large study showed that becoming obese lowered testosterone levels the same as aging 10 years. This may cause mild symptoms such as fatigue, less exercise tolerance, reduced recovery from exercise, mild depressive symptoms, which may lead to more fat gain, which may lead to more severe obesity, which may lead to increased estrogen and suppression of the normal stimulus for testosterone production. This may lead to more symptoms of low testosterone including muscle loss, fat gain, insulin resistance, prediabetes, reduced libido, and erectile dysfunction. So, once the testosterone