Australian Natural Bodz - - Contents -

If you’re car­ry­ing around more ki­los of fat than is good for you, you also have less testos­terone cir­cu­lat­ing in your blood than Mother Na­ture in­tended. Obe­sity in males aged be­tween 14 and 20 can ac­tu­ally halve their testos­terone lev­els, write re­searchers at State Univer­sity of New York at Buf­falo in Clin­i­cal En­docrinol­ogy. In an ear­lier study, the re­searchers looked at the ef­fect of over­weight and di­a­betes on the testos­terone lev­els of men aged over 45. They dis­cov­ered that 40 per­cent of the men with se­ri­ous over­weight – BMI higher than 30 – but no di­a­betes had low testos­terone lev­els. For the se­ri­ously over­weight men with di­a­betes the fig­ure was 50 per­cent. [Di­a­betes Care. 2010 Jun;33(6):1186-92.] Be­cause se­ri­ous weight prob­lems are in­creas­ing among young peo­ple, the re­searchers wanted to know whether testos­terone lev­els were low in over­weight teenagers. That’s why they stud­ied a group of 25 slim and 25 over­weight teenagers. And in­deed, the higher the teenagers’ BMI, the lower the con­cen­tra­tion of free testos­terone in their blood. The over­weight sub­jects had an aver­age BMI of 36; that of the slim sub­jects was 20. The testos­terone [TT] and free testos­terone [cFT] lev­els in the over­weight teenagers were about half those of the slim teenagers. The ac­cepted the­ory is that fat tis­sue con­verts testos­terone into estra­diol. The re­searchers are not sure whether this is the case for this group. How­ever, the over­weight teenagers had a slightly raised estra­diol level, this did not cor­re­late with the re­duced testos­terone level. The re­searchers have put for­ward a dif­fer­ent the­ory: the over­weight teenagers’ in­sulin sen­si­tiv­ity is lower. One mea­sure of in­sulin sen­si­tiv­ity is the HOMA-IR (which is cal­cu­lated by mul­ti­ply­ing the fast­ing glu­cose and in­sulin lev­els with each other). The higher the HOMA-IR, the lower the amount of free testos­terone. The re­searchers sus­pect that re­duced sen­si­tiv­ity to in­sulin prompts the hy­po­thal­a­mus to se­crete less Go­nadotropin-re­leas­ing hor­mone (GnRH). Nor­mally the hy­po­thal­a­mus in­creases its GnRH se­cre­tion if the in­sulin level rises. So GnRH in­di­rectly shuts off the body’s testos­terone pro­duc­tion. “In view of the ris­ing preva­lence of obe­sity, the as­so­ci­a­tion of sig­nif­i­cantly lower testos­terone con­cen­tra­tions with obe­sity in males is alarm­ing and points to ma­jor pub­lic health prob­lem”, the re­searchers con­clude.

Source: Clin­i­cal En­docrinol­ogy doi: 10.1111/cen.12018.

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