Obesity is strongly linked to hypogonadism in males regardless of age
Age-associated changes in hypothalamic-pituitary-testicular function in middle-aged and older men are modified by weight change and lifestyle factors: longitudinal results from the European Male Ageing Study. Camacho EM, Huhtaniemi IT, O’Neill TW, et al. Eur J Endocrinol2013;168(3):445−455.
Determinants of testosterone recovery after bariatric surgery: is it only a matter of reduction of body mass index? Luconi M, Samavat J, Seghieri G, et al. Fertil Steril 2013;99(7):1872−1879.
Testosterone concentrations in young pubertal and post-pubertal obese males. Mogri M, Dhindsa S, Quattrin T, et al. Clin Endocrinol (Oxf) 2013;78(4):593−599.
The role of obesity and type 2 diabetes mellitus in the development of male obesity-associated secondary hypogonadism. Saboor Aftab SA, Kumar S, Barber TM. Clin Endocrinol (Oxf) 2013;78(3):330−337.
This summary presents an overview of four published papers that describe the relationship between obesity and decreased testosterone levels (hypogonadism): one review focusing on the association between obesity, type 2 diabetes mellitus (T2DM) and secondary hypogonadism1 and three clinical studies.2-4 The three clinical studies included a cross-sectional survey assessing the correlation between body mass index (BMI) and sex steroid hormone levels in a general population of 161 males, as well as a longitudinal study investigating the effects of weight loss on sex hormone levels in 24 morbidly obese (BMI >40 kg/m2) males undergoing bariatric surgery;2 a cross-sectional observational study evaluating the impact of obesity on pubertal and post-pubertal males (n=50) aged 14–20 years;3 and a community-based longitudinal survey of 2736 men (baseline age 40–79 years) recruited from eight centers across Europe which aimed to assess the relationship between health and lifestyle factors and reproductive hormone levels in aging men.4
What is known
There is a well-established link between obesity and testosterone deficiency (hypogonadism), and although there appears to be a complex interplay between body composition, obesity, androgen levels, vascular disease and T2DM,1 the exact mechanisms which lead to hypogonadism in obese men have yet to be determined.5-10 It is also well-known that there is a decrease in testosterone levels in men as they age;4,11-13 in younger men, there exists a relationship between T2DM and hypogonadism, with over half of all men with T2DM aged 18–35 years being diagnosed with hypogonadism, with free testosterone levels being negatively related to BMI in this population.3,14 This suggests a possible link between obesity and hormone levels in younger men. However, a large number of the clinical trials investigating the links between obesity and sex hormone concentrations suffer from recruitment biases, and there remain large gaps in the knowledge base, with very few randomized controlled trials conducted to date.2 Further research is required to fully elucidate the mechanisms behind obesity-related hypogonadism and determine potential treatment options.1
What these studies add
The results of the bariatric surgery study confirm the association between hypogonadism and adiposity, with the prevalence of hypogonadism found being similar to that seen in other studies.15,16 A novel result from the study is the demonstration of a non-linear relationship between BMI and sex hormones.2 While previous studies investigating testosterone in adolescents have been conducted,17-20 they did not measure testosterone levels using liquid chromatography tandem mass spectrometry, a sensitive and specific method that is now considered the gold standard method for measuring testosterone.21 The results of the community-based aging study show for the first time that moderate weight loss in males in the general population leads to testosterone increases, and that weight loss of >15% results in increases in both total and free testosterone, demonstrating that in an aging population, obesity prevention is an important factor in maintaining hypothalamic-pituitary-testicular axis functioning, and that weight loss can reverse changes in sex hormone levels.4
Figure 1: Mean change in testosterone levels with bodyweight changes in community-dwelling men4