Another related finding of interest is something called CAG repeat polymorphism. This refers to a coding in a person’s DNA that determines the structure of the androgen receptor. When the CAG repeat polymorphism is longer, more androgen receptors are produced. In men, those with a greater number of repeats have greater lean mass and tend to have less body fat.25
It is likely that optimizing fat loss requires a close attention to both testosterone levels and the testosterone:estrogen ratio. The gain in fat mass seen with aging is related to a drop in both testosterone and estrogen, but the drop in testosterone is much greater, allowing estrogen levels to rise in relation to testosterone.19 However, it is important to note that estrogen can’t simply be eradicated from the system. Men who suffer from a genetic inability to produce estrogen due to aromatase deficiency are insulin resistant, suffer from metabolic challenges and are abdominally obese.26 Of course, the opposite extreme also affects body fat, as men who are genetically prone to generate high levels of estrogen cause a female pattern of fat deposition.27

These findings suggest several avenues of research in treating obesity in men. The simplest may be to provide a moderate, supraphysiologic course of testosterone. This mimics the recreational use of anabolic steroids, which has proven successful for improving body composition and appearance for a vast majority of adult male users. Another avenue may be to investigate the use of a mild aromatase inhibitor. Healthy men given a low dose of an aromatase inhibitor see a dramatic rise in circulating testosterone, as the feedback that regulates testosterone production is dependent, in part, on estradiol.28 By inhibiting estrogen formation, testosterone production is maintained at a higher output. It is important not to fully suppress aromatization, as bone strength is dependent upon estrogen and men who are genetically deficient in aromatase suffer from several metabolic challenges and develop abdominal obesity.