Overweight and obesity are associated with metabolic syndrome and insulin resistance and both have an effect on sexual function. However, the presence of abdominal obesity correlates more strongly with cardiovascular risk factors than a high body mass index (BMI). Therefore, waist circumference measurement is recommended in order to identify the corresponding body weight component of the metabolic syndrome and more than 50% of obese people have a low free testosterone.
Some male patients may develop multiple metabolic risk factors when the waist circumference is only increased to a negligible degree e.g. 94 – 102. These patients often show an important genetic contribution to insulin resistance. These patients should benefit from changes in dietary habits.
-Identification of the metabolic syndrome:
Presence of 3 of the following parameters or risk factors
Waist circumference Abdominal obesity:
-men > 102 cm
-women> 88 cm
Triglyceride level > 150 mg/dl
HDL cholesterol level
-men < 40 mg/dl
-women < 50 mg/dl Blood pressure >130 maximum or systolic
> o = 85 minimum or diastolic
Fasting blood glucose > o = 110 mg/dl
-Insulin Resistance Index: HOMA
Insulin resistance is a decrease in the biological function of insulin characterised by the requirement of a high level of plasma insulin to maintain metabolic homeostasis. It would be involved in several diseases such as type 2 diabetes mellitus, coronary heart disease and high blood pressure. This fact justifies the need for a simple method of determination to identify individuals at risk in the general population.
Matthews et al. presented a mathematical model, homeostasis model assessment (HOMA), which allows for the estimation of insulin resistance and function of pancreatic beta cells by means of fasting plasma glucose and insulin concentrations. This method explores the homeostatic characteristics of a metabolic system to infer the degree of insulin sensitivity compatible with these characteristics. In recent years, this method has been used in several clinical and epidemiological studies, all of them using healthy individuals to establish normal ranges.
-Abdominal fat and erectile dysfunction
Insulin resistance, which results largely from the metabolic disorders caused by abdominal obesity , is one of the factors of the metabolic syndrome, which affects one in four adults. Recent studies in men have shown that abdominal fat increases with age and decreases testosterone concentrations.
Erectile function depends on proper blood filling of the corpora cavernosa of the penis. In people with insulin resistance, the production of nitric oxide that takes place in the internal walls of the arteries (arterial endothelium) is reduced, and that lesser amount of nitric oxide hinders erection.
Too much abdominal fat (the type called visceral adipose tissue that corresponds to 10% of the total normally and not subcutaneous fat that represents 90% of the total) seems to interfere with testosterone production and low testosterone levels create more abdominal fat, unchaining a loop or vicious circle. In addition the production of estrogen which is a female hormone increases.
On the other hand, in a recent study published in 2016, it was found that 50% of obese people with a body mass index (BMI) greater than 30, had testosterone below normal limits. BMI is calculated by dividing weight by height in meters squared.
Therefore in the case of the obese male we are facing the perfect storm to present an erectile dysfunction: a decrease in free testosterone and an increase in estrogen or a hormonal dysfunction coupled with a lower production of nitric oxide, caused by an arterial dysfunction, the two crucial elements for optimal sexual performance.