question: How does high body fat percentages lead to lower testosterone levels?
comment: Estrogen is produced in males via the aromatase mechanism. Excess testosterone turns into estrogen via this mechanism. The aromatase enzyme is produced in adipose tissue. So the more fat you have the more aromatase you have. The more aromatase you have the more testosterone is aromatized into estrogen. So more bodyfat means less testosterone and higher estrogen.
passages: Section::::Aerobic.
  
  In trained long term aerobic exercisers, basal levels are unchanged, or decreased. Acutely, endurance based aerobic efforts cause testosterone to rise.
   Section::::Combined training.
  
  One study showed GH increase with anaerobic effort to be blunted in those who performed aerobic training for 60 minutes prior to strength training. Testosterone levels remained high only at the end of the training session with aerobic training followed by strength training, a phenomenon not seen with weight training done before aerobics. In an 11-week soccer training program focusing on combined vertical jumps, short sprints, and submaximal endurance running, total testosterone increased, but SHBG rose in parallel, maintaining a constant free androgen index.
   BULLET::::- Age: Testosterone levels gradually reduce as men age. This effect is sometimes referred to as andropause or late-onset hypogonadism.
  
  BULLET::::- Exercise: Resistance training increases testosterone levels, however, in older men, that increase can be avoided by protein ingestion. Endurance training in men may lead to lower testosterone levels.
  
  BULLET::::- Nutrients: Vitamin A deficiency may lead to sub-optimal plasma testosterone levels. The secosteroid vitamin D in levels of 400–1000 IU/d (10–25 µg/d) raises testosterone levels. Zinc deficiency lowers testosterone levels but over-supplementation has no effect on serum testosterone.
   Aromatase deficient males experience a normal growth into adulthood. With a very low level of circulating estrogen (7pg/mL), resulting in a higher level of FSH and LH in the blood. Elevated level of androgens do not contribute to harmonic skeletal muscle growth like estrogen, thus, patients exhibits eunuchoid body habitus. 
   Men who produce more testosterone are more likely to engage in extramarital sex. Testosterone levels do not rely on physical presence of a partner; testosterone levels of men engaging in same-city and long-distance relationships are similar. Physical presence may be required for women who are in relationships for the testosterone–partner interaction, where same-city partnered women have lower testosterone levels than long-distance partnered women.
  
  Section::::Biological effects.:Adult.:Fatherhood.
   BULLET::::- Weight loss: Reduction in weight may result in an increase in testosterone levels. Fat cells synthesize the enzyme aromatase, which converts testosterone, the male sex hormone, into estradiol, the female sex hormone. However no clear association between body mass index and testosterone levels has been found.
  
  BULLET::::- Miscellaneous: "Sleep": (REM sleep) increases nocturnal testosterone levels. "Behavior": Dominance challenges can, in some cases, stimulate increased testosterone release in men. "Drugs": Natural or man-made antiandrogens including spearmint tea reduce testosterone levels. Licorice can decrease the production of testosterone and this effect is greater in females.
  
  Section::::Biochemistry.:Distribution.
   Testosterone does not appear to increase the risk of developing prostate cancer. In people who have undergone testosterone deprivation therapy, testosterone increases beyond the castrate level have been shown to increase the rate of spread of an existing prostate cancer.
  
  Conflicting results have been obtained concerning the importance of testosterone in maintaining cardiovascular health. Nevertheless, maintaining normal testosterone levels in elderly men has been shown to improve many parameters that are thought to reduce cardiovascular disease risk, such as increased lean body mass, decreased visceral fat mass, decreased total cholesterol, and glycemic control.
   McDermott (2007) found a significant positive relationship between levels of testosterone and aggression.
  
  Section::::Usage.
   Women who are infertile and have polycystic ovary syndrome show high amounts of android fat tissue. In contrast, patients with anorexia nervosa have increased gynoid fat percentage Women normally have small amounts of androgen, however when the amount is too high they develop male psychological characteristics and male physical characteristics of muscle mass, structure and function and an android adipose tissue distribution. Women who have high amounts of androgen and thus an increase tendency for android fat distribution are in the lowest quintiles of levels of sex-hormone-binding globulin and more are at high risks of ill health associated with android fat 
   Section::::Career.:2015 testosterone rule change.
   The ratio is often used as a biomarker of physiological stress in athletes during training, during athletic performance, and during recovery, and has been explored as a predictor of performance. At least among weight-lifters, the ratio tracks linearly with increases in training volume over the first year of training but the relationship breaks down after that. A lower ratio in weight-lifters just prior to performance appears to predict better performance.
  
  The ratio has been studied as a possible biomarker for criminal aggression, but as of 2009 its usefulness was uncertain.
   There are sex-dependent differences in regional fat distribution. In women, estrogen is believed to cause fat to be stored in the buttocks, thighs, and hips. When women reach menopause and the estrogen produced by ovaries declines, fat migrates from their buttocks, hips, and thighs to their belly.
  
  Males are more susceptible to upper-body fat accumulation, most likely in the belly, due to sex hormone differences.
  
  Abdominal obesity in males is correlated with comparatively low testosterone levels. Testosterone administration significantly increased thigh muscle area, reduced subcutaneous fat deposition at all levels measured, but slightly increased the visceral fat area.
   BULLET::::- Causes subcutaneous fat to be deposited in a masculine pattern and decreases overall body fat
  
  BULLET::::- Suppresses breast development induced by estrogens, but can also still produce gynecomastia via excessive conversion into estradiol if levels are too high
  
  BULLET::::- Maintains skin health, integrity, appearance, and hydration and slows the rate of aging of the skin, but can also cause oily skin, acne, and seborrhea
  
  BULLET::::- Promotes the growth of facial and body hair, but can also cause scalp hair loss and hirsutism
  
  BULLET::::- Contributes to bone growth and causes broadening of the shoulders at puberty
   Section::::Biochemistry.:Levels.
  
  Total levels of testosterone in the body are 264 to 916 ng/dL in men age 19 to 39 years, while mean testosterone levels in adult men have been reported as 630 ng/dL. Levels of testosterone in men decline with age. In women, mean levels of total testosterone have been reported to be 32.6 ng/dL. In women with hyperandrogenism, mean levels of total testosterone have been reported to be 62.1 ng/dL.
  
  Section::::Measurement.
  
  Testosterone’s bioavailable concentration is commonly determined using the Vermeulen calculation or more precisely using the modified Vermeulen method, which considers the dimeric form of sex-hormone-binding-globulin.
   At the end of his experiment, Naughton details an additional experiment inspired by his research into the lipid hypothesis. In this second experiment, he cuts out most sugars and starches from his diet for a month, eating foods such as cheeseburgers without buns, eggs and bacon fried in butter, steaks, Polish sausage, fruit in heavy cream, and green vegetables in butter. He uses coconut oil to fry onions for his cheeseburgers and eats fried shredded cheese as a snack. As a result, Naughton says that his energy level and mood have suffered no deleterious effects, despite him often working until 2 AM on a large programming project with a tight deadline. At the end of the month, his overall cholesterol has dropped from 222 to 209, with his LDL having dropped from 156 to 130 and his HDL having increased from 49 to 64.
   Low levels of insulin can also lead to hyperandrogenism. When the body's insulin levels drop too low, it can force itself to produce too much in an effort to make up for the loss. The result of such an overproduction is a disorder called hyperinsulinemia. An effect of hyperinsulinemia is the body's increased production of androgens in the ovaries. This is all part of HAIR-AN syndrome, a multisystem disorder that involves increased insulin levels that prompt increased androgen levels.
  
  Section::::Causes.:Cushing’s syndrome.
   Section::::Anaerobic.
  
  It is unknown if anaerobic training changes individual hormone profiles, or if conditioned athletes in studies self-selected because of physiologic predisposition to athletic conditioning. There is variation of response to anaerobic stress depending on exercise intensity, age, gender, length of time studied, and time at which serum indices were drawn. Most studies report that testosterone increases or is unchanged acutely, though some even report it to decrease. Anaerobic exercisers have testosterone levels below sedentary controls in cross sectional analysis. Over months to years, levels are stable to slightly increased.
   In males, transdermal estradiol replacement enable epiphyseal plates closure, increases bone density, promote skeletal maturation, lower FSH and LH level to normal and decrease insulin blood concentration. In a young man with high stature due to unfused epiphysis, estrogen patch treatment daily possibly for life resolved the issue with further growth and osteoporosis. 
   High androgen levels are associated with menstrual cycle irregularities in both clinical populations and healthy women.
  
  Section::::Biological effects.:Adult.:Sexual arousal.
   Decreased systemic testosterone in men has also been reported in men with heart failure, whereby the severity of the disease is proportional to the reduction in systemic testosterone levels. Although a direct mechanism of action is not fully understood, some research attribute low testosterone to advancing side effects of heart failure, such as decreased exercise ability, decreased muscle mass, fatigue/dyspnea and cachexia.
  
  Section::::Testosterone replacement therapy.
   Testosterone promotes prostate cell proliferation, but relatively low levels of serum testosterone are found in patients with BPH. One small study has shown that medical castration lowers the serum and prostate hormone levels unevenly, having less effect on testosterone and dihydrotestosterone levels in the prostate.
   On the other hand, estrogens reduce muscle mass. Muscle mass changes over time as a result of changes in testosterone and estrogen levels and exercise, besides other factors.
  
  Section::::Physiology.:Changes to body shape.
  
  The aging process has an inevitable impact on a person's body shape. A woman's sex hormone levels will affect the fat distribution on her body. According to Dr. Devendra Singh, "Body shape is determined by the nature of body fat distribution that, in turn, is significantly correlated with women's sex hormone profile, risk for disease, and reproductive capability." Concentrations of estrogen will influence where body fat is stored.
   Section::::Biological function.:Fat deposition.
  
  Males typically have less body fat than females. Recent results indicate androgens inhibit the ability of some fat cells to store lipids by blocking a signal transduction pathway that normally supports adipocyte function. Also, androgens, but not estrogens, increase beta adrenergic receptors while decreasing alpha adrenergic receptors- which results in increased levels of epinephrine/ norepinephrine due to lack of alpha-2 receptor negative feedback and decreased fat accumulation due to epinephrine/ norepinephrine then acting on lipolysis-inducing beta receptors.
  
  Section::::Biological function.:Muscle mass.
   Normal total testosterone levels depend on the man's age but generally range from 240–950 ng/dL (nanograms per deciliter) or 8.3-32.9 nmol/L (nanomoles per liter). According to American Urological Association, the diagnosis of low testosterone can be supported when the total testosterone level is below 300 ng/dl. Some men with normal total testosterone have low free or bioavailable testosterone levels which could still account for their symptoms. Men with low serum testosterone levels should have other hormones checked, particularly luteinizing hormone to help determine why their testosterone levels are low and help choose the most appropriate treatment (most notably, testosterone is usually not appropriate for secondary or tertiary forms of male hypogonadism, in which the LH levels are usually reduced).
   Mounting evidence indicates that the amount and type of fat in the diet can have important effects on bone health. Most of this evidence is derived from animal studies. The data from one study indicated that bone mineral density is negatively associated with saturated fat intake, and that men may be particularly vulnerable.
  
  Section::::Dietary recommendations.
  