Lower total and free testosterone and SHBG concentrations were observed among men with higher body fatness, whereas lower total and free estradiol, and androstanedial glucuronide concentrations were observed among men with lower body fatness.[4] Total testosterone and SHBG concentrations were higher with slightly lower BMI, waist circumference, and percent body fat, implying that even a modest loss of body fat could improve testosterone and SHBG profiles.[4] This large NHANES III analysis focuses on body fatness and sex steroid hormones; it does not report that being underweight is associated with deficient dihydrotestosterone (DHT) levels, and instead shows that lower body fat tends to be associated with *higher* testosterone and SHBG.

In normal men, mean plasma DHT was 54.7 ± 19 ng/dL in young adults aged 21–37 and 39.1 ± 19 ng/dL in older adults aged 65–90. This paper establishes reference values for circulating DHT in men, but it does not link DHT deficiency to being underweight.

Baseline levels of dihydrotesterone (DHT), 17 hydroxy progesterone (OHPROG), sex hormone-binding globulin (SHBG), and testosterone (TESTO) were negatively associated with fat mass and abdominal fat (P < 0.0001) in men. In men, low DHT, OHPROG, SHBG, and TESTO were associated with higher adiposity and abdominal and visceral fat. Thus, in this cohort, lower DHT was linked to **higher** fat mass, not to being underweight or having low BMI.

In BMI-discordant pairs (mean ΔBMI=5.9 kg/m^2), serum dihydrotestosterone (DHT) was lower [mean 1.9 (SD 0.7) vs. 2.4 (1.0) nmol/L, P=0.040] and mRNA expressions of DHT-inactivating AKR1C2 (P=0.021) and cortisol-producing HSD11B1 (P=0.008) higher in the heavier compared to the leaner co-twins.[9] Within all twin pairs, i.e. independent of genetic effects and age, 1) the amount of subcutaneous fat inversely correlated with serum total and free testosterone, DHT, and sex hormone-binding globulin (SHBG) concentrations (P<0.01 for all).[9] In conclusion, acquired adiposity was associated with decreased serum DHT and increased estrogen concentrations, independent of genetic factors and age.[9] This twin study describes *lower* DHT in heavier men with more adiposity, not deficiency of DHT in underweight men.

Overall, serum testosterone, free-testosterone, and DHT levels were lower in HIV-infected men than in healthy men, but serum DHT-to-testosterone ratios were not significantly different between the two groups.[2] Serum total- and free-testosterone levels were lower in HIV-infected men who had lost 5 lb or more of weight in the preceding 12 months than in those who had not lost any weight. Serum DHT levels and DHT-to-testosterone ratios did not differ between those who had lost weight and those who had not.[2] We conclude that DHT levels are lower in HIV-infected men than in healthy men but that neither DHT levels nor DHT-to-testosterone ratios correlate with weight loss.[2] This clinical study explicitly reports that DHT levels did *not* differ with weight loss, arguing against a simple causal link between being underweight and DHT deficiency in men.

Dihydrotestosterone (DHT) is produced from testosterone by the enzyme 5-alpha-reductase in tissues including the prostate gland, seminal vesicles, epididymides, skin, hair follicles, liver and brain.[1] Circulating DHT levels in eugonadal men are about 7- to 10-fold lower than those of testosterone, and plasma levels of testosterone and DHT are highly correlated (correlation coefficient of 0.7).[1] Other studies and labs assessing circulating total DHT levels with LC–MS/MS have reported ranges of 11–95 ng/dL in adult men, and 14–77 ng/dL for healthy adult men aged 18–59 years.[1]

In this cohort of older men free of CVD and diabetes, baseline levels of DHT were strongly associated with lower risk of diabetes and with less insulin resistance by HOMA-IR. In this study of older men, we found a clear association of low DHT levels with higher insulin resistance and higher risk of diabetes. Low levels of T and DHT have been reported in men with metabolic syndrome and/or type 2 diabetes, and T deficiency has been associated with obesity (particularly visceral), insulin resistance, and dyslipidemia, indicating that low DHT is typically seen with **metabolic syndrome/obesity**, not specifically underweight.

Our results suggest that there is a causal effect of BMI on serum testosterone in men. A 1 SD genetically instrumented increase in BMI was associated with a 0.25 SD decrease in serum testosterone (IV ratio: -0.25, 95% CI: -0.42 to -0.09, p = 2.8×10⁻³). For a body weight reduction altering the BMI from 30 to 25 kg/m², the effect would equal a 13% increase in serum testosterone. This bidirectional Mendelian randomization shows higher BMI (overweight/obesity) lowers testosterone; it does **not** show that low BMI causes low testosterone or low DHT.

Our findings support the view that symptoms of male aging might partly be explained by lower DHT concentrations, especially in subjects with serum T concentrations which are considered eugonadal.[3] The presence of symptoms of hypogonadism with biochemically normal levels of T but low concentrations of DHT is, therefore, clinically relevant and may help in explaining male aging-related complaints.[3] This study associates low DHT with symptoms of hypogonadism even when testosterone is normal, but it does not identify low BMI or underweight status as a causal factor for DHT deficiency.

Dihydrotestosterone (DHT) is a potent androgen derived from testosterone by the action of 5α-reductase.[8] DHT levels are helpful in the diagnosis of 5-alpha-reductase deficiency and male-pattern baldness.[8] Low DHT levels are seen in conditions such as 5-alpha-reductase deficiency and low testosterone (male hypogonadism), where “as your body converts testosterone to DHT, if you have low levels of testosterone, you’ll have lower-than-normal levels of DHT as well.”[10]

DHT does not play a substantive role in body composition compared to testosterone under normal conditions. Elevated levels of DHT in response to testosterone replacement therapy are unlikely to appreciably impact lean or fat mass. The review also notes a normal DHT range of 11 to 95 ng/dL from a clinical laboratory using LC-MS/MS.

In summary, observational studies consistently show a strong association of obesity with low circulating testosterone levels in men. A cross-sectional study of 314 Chinese men similarly found that older obese men (defined by BMI >28 kg/m² for these Asian men) had a 3 nmol/L lower testosterone level compared to age-matched lean men. The bidirectional, inverse relationship between increased fat mass and testosterone levels suggests that both weight loss as well as testosterone therapy have the potential to break this vicious cycle. These data focus on **obesity-related** low testosterone, not on underweight men causing hormone deficiency.

Genetically predicted BMI was negatively associated with TT (IVW: β = -0.24 [95% CI: -0.28 to -0.20], P = 1.6×10⁻³⁰). These results showed that genetically higher fat mass was associated with lower testosterone levels in men of European ancestry but that genetically predicted fat-free mass was either only weakly associated or not statistically associated with testosterone levels. Thus, higher adiposity (not low BMI) is causally linked to lower testosterone; effects on DHT are not specifically tied to underweight status in this analysis.

We found that obese men and underweight men had increased prevalence of secondary hypogonadism as compared to men with normal body mass index.[5] The prevalence of secondary hypogonadism showed a U-shaped association with BMI, being higher in obese and underweight men.[5] This retrospective analysis shows that underweight men have more secondary hypogonadism (low testosterone due to pituitary/hypothalamic causes), but it does not detail dihydrotestosterone levels or claim that underweight status causes a specific DHT deficiency.

Serum concentrations of dihydrotestosterone (DHT), total testosterone (T) and calculated free testosterone (FTc) were measured in 1,998 men.[9] Body mass index (BMI) had low-moderate negative correlation with all androgens (T, rho = −0.40, p < 0.001; FTc, rho = −0.27, p < 0.001; DHT, rho = −0.39, p < 0.001).[9] These data indicate that higher BMI (overweight/obesity) is associated with lower levels of T and DHT, while the study does not report a specific deficiency of DHT caused by being underweight.[9]

The results of these cross-sectional analyses suggest that higher levels of E2 and the ratio of E2/T in men are associated with greater fat mass, whereas higher levels of T and to some extent SHBG are associated with lower fat mass.[7] In multivariable-adjusted models, we observed significant positive associations of FE2 and E2/T with percentage total and trunk fat mass, as well as weight, BMI, and waist and hip circumference; in contrast, higher levels of TT and FT were associated with lower absolute and relative measures of total, trunk, and appendicular fat mass and lower weight, BMI, waist and hip circumference, and WHR.[7] This study links higher testosterone to lower fat mass and lower BMI, but does not report that men with very low BMI or who are underweight have deficient DHT; DHT is not discussed as being specifically reduced in underweight individuals.

A greater waist circumference or body mass index (BMI) was found to be correlated with reduced levels of serum free and total testosterone in previous studies. In a systemic review, MacDonald et al. concluded that there was a strong negative relationship between higher BMI and serum testosterone levels. Another study revealed that a lower serum testosterone level was associated with greater waist circumference despite the low BMI. This work characterizes testosterone deficiency as linked to **central adiposity and higher BMI**, and does not identify underweight as a typical cause of androgen deficiency.

Central adiposity was associated with lower DHEAS levels at follow-up, while elevated body mass index was not.[6] Central adiposity may be a more important predictor of decline in DHEAS than is body mass index.[6] This longitudinal study of the Massachusetts Male Ageing Study investigates BMI, waist circumference and sex steroid changes, emphasizing central adiposity rather than low BMI as a predictor of hormone decline; it does not support a specific claim that being underweight causes deficiency of DHT.

Within a broad range from low to high-normal serum testosterone concentrations, prostatic DHT concentrations remain stable.[12] As a result of the prostatic pathways for DHT production, modest decreases in serum testosterone result in no change in normal prostatic DHT concentration.[12] Circulating DHT concentrations have little relationship to prostatic and skin DHT concentrations, and data from trials of 5α-reductase inhibitors have demonstrated that DHT does not appear to be necessary for the direct effects of testosterone on muscle function and erythropoiesis.[12]

Significant inverse correlation of serum total testosterone with BMI (r = -0.311, p = 0.000) was recorded in this study. Serum total testosterone has a significant negative correlation with BMI of middle aged men working at Dow University. This indicates that higher BMI is associated with lower testosterone; the study does not present evidence that being underweight causes testosterone or DHT deficiency.

Obesity is the commonest cause of low testosterone in men.[7] Although difficult to achieve and sustain, moderate weight loss (<10%) can increase testosterone levels by 2–3 nmol/L.[7] This clinical review on male androgen disorders emphasizes the association of low testosterone (and androgen deficiency) with obesity and metabolic syndrome, and does not identify being underweight as a typical cause of androgen deficiency.[7]

We found that obese men and underweight men had increased prevalence of secondary hypogonadism as compared to men with normal BMI. Among our study participants, we found that obesity class II and III as well as underweight men had a higher prevalence of secondary hypogonadism compared to normal BMI controls. Males at BMI extremes (i.e., Obesity Class II-III and underweight) have a higher prevalence of secondary hypogonadism. This suggests that very low BMI can be associated with low testosterone (hypogonadism), but the study does not specifically examine DHT or claim that underweight status causes isolated DHT deficiency.

After adjusting for all potential covariates, there was a similar J-shaped relationship between BMI and TD, with an inflection point of 19.2 kg/m². BMI was positively correlated with TD when it was over 19.2 kg/m² and inversely correlated with TD when it was below 19.2 kg/m². When BMI was less than 19.2 kg/m² (left side of the cut point), a borderline negatively significant association for TD was detected (OR = 0.6 [0.4, 1.0], p = .043). The probability of TD declined as BMI increased. However, a surprising observation noted in our study was the lack of a relationship between lower BMI and a lower likelihood of hypogonadism. When the BMI decreased below a certain level, extreme underweight may also lead to TD. This highlights that both obesity and extreme underweight can be linked to testosterone deficiency, but DHT was not directly measured.

Low Dihydrotestosterone (DHT) occurs when the body produces insufficient levels of this potent androgen, which is derived from testosterone via the 5-alpha reductase enzyme.[12] Certain conditions can suppress DHT production: pituitary or adrenal gland disorders (e.g., adrenal insufficiency); obesity (linked to increased estrogen, which lowers androgens); chronic stress (elevated cortisol suppresses testosterone/DHT).[12] This functional medicine explainer lists obesity, endocrine disorders and chronic stress as factors that can lower DHT, but does not cite underweight status or low BMI as a recognized cause of DHT deficiency in men.

Body fatness was most strongly associated with total testosterone and SHBG concentrations such that a higher BMI of less than 1 kg/m², a higher waist circumference of approximately 2 cm, or a 1% higher body fat percentage would result in a 2% lower geometric mean concentration of these two analytes. The authors report that body fatness was adversely associated with serum testosterone and SHBG concentrations in men. Again, the focus is on **higher** BMI and adiposity lowering testosterone, with no indication that low BMI per se causes DHT deficiency.

Standard Range: Male: 12 - 65 ng/dL (0.41 - 2.24 nmol/L).[8] Low DHT in men is associated with an increased risk of ischemic heart disease and stroke, insulin resistance, metabolic syndrome, diabetes, and cognitive decline (Swerdloff 2017).[8] This practitioner-oriented summary discusses reference ranges and risks associated with low DHT, attributing low DHT to metabolic and cardiovascular issues but does not state that being underweight in men causes a deficiency of DHT.

In adult eugonadal men, serum DHT concentrations are most accurately measured by LC-MS/MS, and consistent normal ranges based on this assay platform have been reported across several studies of men spanning a wide age range.[4] A DHT reference range of 14 to 77 ng/dL (0.47 to 2.65 nmol/L) for healthy adult men has been reported, and a DHT range of 23 to 102 ng/dL for community-dwelling adult men under 65 years.[4] These data characterize normal DHT ranges but do not identify underweight status as a specific cause of DHT deficiency within eugonadal men.[4]

In our study, we found that BMI correlated inversely with the serum testosterone level, and the relation was also revealed by the results of linear regression. To further evaluate the finding, a scatter plot for the serum testosterone level and BMI showed that nearly all patients with BMI >25 had serum testosterone levels of <5 ng/mL. CONCLUSION: In the infertile Taiwanese male population, obese patients (BMI ≥30) and overweight patients (BMI ≥25) had significant lower serum testosterone than the nonoverweight patients. This indicates testosterone deficiency is more prevalent with **overweight/obesity** rather than underweight in this cohort.

Adult male DHT reference range is reported as 0.32 – 1.64 nmol/L.[6] The test information notes that DHT measurement is used in the investigation of 5α-reductase deficiency and disorders of sexual development.[6] No mention is made of underweight or low BMI as a typical cause of abnormal DHT levels; instead, genetic enzyme deficiencies and androgen-related conditions are the main indications.[6]

Certain conditions are associated with low levels of DHT, including: 5-alpha reductase deficiency and low testosterone (male hypogonadism). The article describes DHT as a hormone derived from testosterone and notes that low testosterone can lead to low DHT. It does not list low BMI or being underweight as a recognized cause of DHT deficiency; rather, DHT deficiency is linked to specific enzyme defects or generalized androgen deficiency.

In this Korean-language review article, the author states that very low body fat can reduce male hormone secretion for survival, while excess body fat can lower testosterone via aromatase. The passage concerns testosterone and body fat, not a direct claim that underweight men develop DHT deficiency.

This Korean article states that unusually low body-fat percentage can reduce male hormone secretion for survival, and that obesity can lower testosterone by increasing aromatase activity. It does not provide direct evidence that underweight men have DHT deficiency.

The article says that testosterone levels can be reduced by extremely low body fat, malnutrition, and excessive exercise. It is secondary health-content reporting and does not directly measure DHT in underweight men.

Dihydrotestosterone (DHT) is a potent androgen derived from testosterone via 5-alpha-reductase and plays a key role in male sexual development, prostate growth and hair follicle biology.[10] Low DHT levels are classically associated with 5-alpha-reductase deficiency and hypogonadism, while high DHT contributes to conditions like benign prostatic hyperplasia and androgenic alopecia.[10] This encyclopedia-style entry summarizes biochemical roles and clinical uses of DHT measurement; it does not identify low BMI or underweight status as a direct cause of DHT deficiency.

The blog claims that obesity lowers male hormones and that underweight, malnutrition, and excessive exercise can lower testosterone levels and fertility. This is a blog post and does not constitute primary evidence about DHT deficiency.

One Reddit user comments that “Low body fat usually increases DHT conversion,” suggesting an anecdotal belief that lower fat mass may raise, rather than lower, DHT.[11] This is an informal, non-peer-reviewed opinion and does not constitute clinical evidence; it illustrates that some lay perspectives link low body fat with higher DHT rather than DHT deficiency.[11]

The page states that green tea is known to inhibit DHT production. It is unrelated to whether underweight men have DHT deficiency and is not a primary source.