Short-Term Estrogen Withdrawal Increases Adiposity in Healthy Men.

Publication Type:

Journal Article

Source:

The Journal of clinical endocrinology and metabolism, p.jc20161482 (2016)

Abstract:

CONTEXT: Testosterone deprivation increases risk of insulin resistance in men, but whether this risk is independent of changes in body composition is unknown. Further, the metabolic roles of testosterone and its metabolite estradiol have not been clearly defined in men.

OBJECTIVE: To establish the effects of selective sex steroid withdrawal on insulin sensitivity in healthy men Design: Double-blinded, placebo-controlled, randomized trial Setting: Academic medical center Participants: 56 healthy men, 19-55 years of age Interventions: Subjects received the GnRH antagonist acyline plus one of the following: placebo gel (Castrate), 1.25g testosterone gel (Low T/E), 5g testosterone gel (Normal T/E), or 5g testosterone gel with letrozole (Normal T/Low E) daily for 4 weeks. Body composition and glucose tolerance were assessed at baseline and end-of-treatment.

MAIN OUTCOME MEASURE: Insulin sensitivity quantified by the Matsuda index Results: Predicted circulating sex steroid concentrations were achieved in all treatment groups. The time-by-group interaction for Matsuda index did not achieve significance in overall repeated measures analysis of variance (baseline vs. week 4, p=0.16). A significant time-by-group interaction was observed for fat mass (p=0.003), with changes in fat mass attributable predominantly to estrogen exposure in linear regression analysis (p=0.016). A time-by-group interaction also was observed for lean mass (p=0.03) and influenced by androgen exposure (p=0.003).

CONCLUSIONS: Short-term sex steroid withdrawal in healthy men causes adverse changes in body composition. These findings support the role of estradiol as a determinant of adiposity in men.