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Horm Metab Res 2014; 46(04): 283-286
DOI: 10.1055/s-0033-1358678
Endocrine Care
© Georg Thieme Verlag KG Stuttgart · New York

Caloric Restriction Increases Serum Testosterone Concentrations in Obese Male Subjects by Two Distinct Mechanisms

D. M. Schulte
1   Department of Internal Medicine I, University of Kiel, Kiel, Germany
2   Cluster of Excellence Inflammation at Interfaces, University Kiel, Kiel, Germany
3   Center for Endocrinology, Diabetes and Preventive Medicine, University of Cologne, Cologne, Germany
,
M. Hahn
4   Institute of Medical Statistics, Informatics and Epidemiology, University of Cologne, Cologne, Germany
,
F. Oberhäuser
3   Center for Endocrinology, Diabetes and Preventive Medicine, University of Cologne, Cologne, Germany
,
G. Malchau
5   Department of Clinical Chemistry, University of Cologne, Cologne, Germany
,
M. Schubert
6   Department of Internal Medicine, SCIVIAS Hospital St. Josef, Rüdesheim am Rhein, Germany
,
C. Heppner
7   Endokrinologikum Göttingen, Göttingen, Germany
,
N. Müller
1   Department of Internal Medicine I, University of Kiel, Kiel, Germany
,
H. Güdelhöfer
3   Center for Endocrinology, Diabetes and Preventive Medicine, University of Cologne, Cologne, Germany
,
M. Faust
3   Center for Endocrinology, Diabetes and Preventive Medicine, University of Cologne, Cologne, Germany
,
W. Krone
3   Center for Endocrinology, Diabetes and Preventive Medicine, University of Cologne, Cologne, Germany
,
M. Laudes
1   Department of Internal Medicine I, University of Kiel, Kiel, Germany
2   Cluster of Excellence Inflammation at Interfaces, University Kiel, Kiel, Germany
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Publikationsverlauf

received 12. Juli 2013

accepted 07. Oktober 2013

Publikationsdatum:
06. November 2013 (online)

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Abstract

The concentration of serum testosterone is mainly regulated by the testicular function, which is under control of the central hypothalamic-pituitary-gonadal axis. A certain amount of testosterone is converted into β-estradiol by adipose tissue. Obesity in men is often associated with decreased androgen levels. The aim of the present study was to examine the effect of caloric restriction on serum testosterone levels in obese men. Dietary intervention study was performed with a very low calorie diet (800 kcal/d) for 12 weeks. Thirteen obese human male subjects (median body mass index: 42.7 kg/m2) were included. Body composition was assessed by impedance analysis. Insulin sensitivity was estimated by leptin-to-adiponectin ratio (LAR). Testosterone (T), β-estradiol, albumin, sex hormone-binding globulin (SHBG), LH, and FSH serum concentrations were measured by enzyme immunoassays. Statistical analysis was performed on baseline and values after 3 months. Caloric restriction significantly increased total testosterone (6.97 nmol/l to 13.21 nmol/l; p=0.001) and SHBG (22.11 nmol/l to 42.12 nmol/l; p=0.001) concentrations in serum. This is caused by a significant improvement of the testicular function (LH/T: 0.36–0.20; p=0.005) and a significant reduction of the T/β-estradiol conversion rate (73.59–104.29; p=0.003). There was a significant negative correlation of improvement of testicular function and LAR (rs=−0.683 (p=0.042)). In obese men caloric restriction significantly increases the serum testosterone concentration. This is achieved by 2 distinct mechanisms, that is, improvement of testicular function and reduced conversion of testosterone to β-estradiol by aromatase activity of the adipose tissue.

Key words

obesity - testosterone - inflammation - nutritional intervention