Fat High, T Low
By: Jerry Brainium
Those interested in increasing their testosterone levels in a completely natural manner'without using any type of drug or even food supplement'may be interested in what follows. One caveat, however: The information applies only if you have excess bodyfat. Studies show that testosterone levels bear a direct relationship to bodyfat levels. Generally, the fatter you are, the lower your total testosterone levels.
That's due to either a decreased level of a protein that carries testosterone in the blood or a decrease in the pituitary hormones that dictate testosterone synthesis and release. The blood protein that carries testosterone, sex-hormone-binding globulin (SHBG), is usually lower in men who have higher percentages of bodyfat. On the other hand, testosterone isn't active when it's bound to this protein. Only unbound, or free, testosterone can interact with cellular steroid receptors.
Most studies show little or no effect of bodyfat levels on free testosterone, but some show an inverse relationship between free testosterone levels and obesity. A lowered free-testosterone level most often reflects a problem with the release of pituitary hormones that control testosterone release, such as luteinizing hormone (LH). Decreased SHBG levels lower total testosterone levels because unbound testosterone is more subject to degradation or conversion into estrogen by aromatase enzymes, which are found in many tissues but particularly in bodyfat.
A new study sought to clear up the confusion over the relationship between testosterone, both free and bound, and bodyfat levels.1 The study featured two groups of obese men, ages 20 to 68. The subjects ate a 1,200-calorie diet for six months, and researchers monitored their hormone levels before and after the diet. To make the dieting process easier for the men, they were also given dexfenfluramine (15 milligrams a day) to help curb their appetites. They were compared to 20 other men who had normal bodyfat levels.
One reason obesity leads to a reduction of total testosterone is that higher levels of bodyfat are associated with elevated insulin levels. Insulin, in turn, decreases the synthesis of SHBG in the liver, leading to the drop in circulating total testosterone. As SHBG drops, free testosterone should increase, but with higher levels of bodyfat it's simply converted into estrogen by aromatase enzymes in fat tissue. The same holds true for pro-hormone supplements used by people who have higher bodyfat levels.
Losing bodyfat results in lower resting insulin levels, which leads to increased production of SHBG in the liver and, consequently, higher total testosterone levels in the blood. In the study discussed here, total testosterone and insulin levels didn't differ significantly between massively fat and moderately fat men, but the moderately fat men did show higher free-testosterone levels than the extremely fat men.
Once bodyfat exceeds a certain level, secretion of pituitary hormones that control testosterone release, such as luteinizing hormone, is blunted. Recent studies link that process to increased levels of leptin, a protein released from fat that acts as a fat signal to the brain. Fat people show higher levels of leptin, ostensibly due to a lack of leptin interaction in the brain. Higher leptin levels also interfere with testosterone synthesis in the Leydig cells of the testes, which explains the lower free-testosterone levels in very fat men.
But this study reported that both moderately and massively obese men showed higher total and free-testosterone levels, as well as higher LH levels along with lower insulin levels, after they lost bodyfat by dieting. Despite the decreased level of free testosterone in the very fat men, their sex lives and sex drives weren't noticeably affected. Free testosterone controls sex drive in both sexes, so the finding indicates that the obese men apparently still had enough free testosterone for sexual functioning.