The National Center for Health Statistics Research Ethics Review Board has thoroughly examined and endorsed the NHANES study and its protocols. Consequently, our analysis focused on 5959 aged 18–59 years old, who had complete data and underwent DXA scans. The data for this study were obtained from the National Health and Nutrition Examination Survey (NHANES) conducted by the Centers for Disease Control and Prevention (CDC) and the National Center for Health Statistics (NCHS) between 2011 and 2016. However, these studies have been limited by small sample sizes, which may limit their generalizability and statistical power. Testosterone can also affect muscle quality, fat distribution, and metabolic status by regulating protein and fat metabolism . Therefore, the results of this study contribute to a deeper understanding of the relationship between testosterone and fat distribution, and further exploration of the impact of testosterone levels and female body composition in high androgen-related diseases such as PCOS and hyperandrogenism. In males, testosterone is known to play a critical role in the regulation of metabolism, and studies have shown that low testosterone levels may lead to obesity. Specifically, it was observed that male participants exhibited higher overall energy intake, while simultaneously presenting lower levels of total protein intake (TPF), amino acid intake (APF), glucose intake (GPF), and body mass index (BMI) in comparison to their female counterparts. We excluded 8,686 participants with incomplete body composition data, 4,091 participants under the age of 18 and 2,856 participants who had taken medications known to potentially affect testosterone levels (e.g., birth control pills, estrogen, aldactone). Multivariable linear regression models were used to assess the association between testosterone levels and body composition parameters, including total percent fat (TPF), android percent fat (APF), gynoid percent fat (GPF), android to gynoid ratio (A/G), and lean mass percent (LMP). This study aims to investigate the relationship between testosterone and obesity by analyzing the correlation between testosterone levels and body fat percentage using data from the NHANES (National Health and Nutrition Examination Survey) database. Here’s a simplified guide to testosterone levels in males and females by age, designed to be easy to read and understand. The proper balance between testosterone (along with other androgens) and estrogen is important for the ovaries to work normally. If you thought testosterone was only important in men, you'd be mistaken. There may be other important functions of this hormone that have not yet been discovered. If you’re experiencing symptoms of low testosterone, it’s crucial to seek professional guidance to address these issues safely and effectively. In men, it’s diagnosed when levels fall below 300 nanograms per deciliter (ng/dL). Doing basic tests, where only total testosterone level is measured, might be confusing because you wouldn't understand why you had symptoms of testosterone deficiency while other men didn't. Bioavailable testosterone is more readily able to enter your cells and be used by your body — that's why this parameter is essential. It is also suggested for males with libido/erection disorders and females with virilization symptoms. Regular exercise, especially resistance training, has been shown to potentiate muscle hypertrophy and increase testosterone levels (Vingren et al., 2010). A recent double-blind randomized controlled trial (RCT) reported modest but significant improvements in muscle mass and strength after 3 years of testosterone administration in older men with low-to-normal testosterone levels (Hildreth et al., 2013). Serum testosterone levels also decline by ∼110 ng/dL per decade in older adults (Morley et al., 1997), prompting interest in their interplay with muscle health. The smooth curve fittings between APF, GPF, and testosterone levels were similar to those of TPF with testosterone levels, which are presented in the S1 and S2 Figs.Open in a new tab(a) Each black point represents a sample. A negative correlation was found between LMP and testosterone levels. Conversely, a significantly positive association was found between LMP and testosterone levels. Since testosterone levels decrease as men age, testosterone is sometimes used in older men to counteract this deficiency. Insufficient levels of testosterone in men may lead to abnormalities including frailty, accumulation of adipose fat tissue within the body, anxiety and depression, sexual performance issues, and bone loss. Instead, there is no significant correlation between testosterone and body composition in females. The increased activity of steroid-converting enzymes in PCOS patients indicates that adipose tissue function is influenced by these sex steroid hormones at the tissue level. On the other hand, in males, testosterone supplementation can promote lipolysis by increasing expression of norepinephrine and β-adrenergic receptors in adipocytes , and inhibit lipid storage by reducing LPL activity on adipocyte surfaces .
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