Chicken or Egg: Testosterone vs Weight Loss

This past week saw two testosterone-related abstracts announced at ENDO 2012, the annual meeting of the Endocrine Society.  I generally don't like to get too excited over abstracts announced at specialty meetings as we don't have access to the data, methodology & statistical mumbo-jumbo that led to the headline grabbing conclusion.  

In the initial announcement, the authors noted that a prospective cohort of 255 hypogonadal men (avg baseline T 287ng/dL) being treated w/testosterone lost a significant amount of weight & inches in their waist.  They started out weighing an avg 236 pounds w/most having body mass index >25kg/m2, two-thirds of whom were either obese (BMI 30-40kg/m2) or morbidly obese (BMI >40kg/m2) w/avg waist 42" and two-thirds >40".

Using a form of testosterone (undecanoate) not yet available in the States, the subjects received 1,000mg initially and again 6 weeks later.  They then went on to receive 1,000mg every 12 weeks.  T normalized (>350ng/mL) within the initial 6-9 months and stayed significantly (level not mentioned) above baseline by 12 months.

Weight loss was demonstrated within the initial 12 months and continued as long as 5 years out at the end of the study w/more than half losing at least 33 pounds (~15%), and a third losing 44 pounds or more (~20%). 4 out of 5 men lost 2" in their waist while close to half lost 6" or more.  

What's remarkable is that weight loss was not a goal of the study.  As a comparison, the Food & Drug Administration approved lorcaserin earlier this week as a weight loss adjunct to diet & exercise based upon its avg 3.3% additional weight loss, although one third of the subjects did lose 25 pounds or 11% of their body weight.  

In the 2nd announcement this week regarding testosterone, the authors followed a number of obese men avg 53yo w/BMI 32kg/m2 & waist ~42" w/insulin-resistant pre-diabetes (elevated fasting insulin & impaired fasting glucose plus elevated Hemoglobin A1c (~6%).  Subjects were randomized to lifestyle intervention (150 minutes of physical activity each week plus less fat & calories) vs metformin vs placebo.  Across the board, avg T was 394-417ng/dL w/20-25% hypogonadism (T <300ng/dL).  

After a year of exercise & improved nutrition, avg T increased 10% from 417ng/dL to 460ng/dL w/less men being considered hypogonadal in that group alone.  In other words, placebo & metformin made no difference in T production, only exercise & nutrition.  Furthermore, those in the lifestyle modification lost ~17 pounds while those on metformin lost 6 pounds compared to no loss in the placebo group.

Two thoughts came to mind as I tried to put these abstract announcements into perspective.  First, we shouldn't have to wait 6-9 months to reach optimal T levels (instead, inject T cypionate weekly & reach steady state within a month or so (or use some daily product & reach steady state with a week or so)) and appropriately treat hypogonadal signs & symptoms.  Second, just like the chicken & the egg, we still don't know whether T or exercise has the stronger impact on the other.  But my thought is this: if you don't feel better and see results after a reasonable effort at (no risk/no cost/no downside) diet & nutrition, find out if you're hypogonadal and in need of testosterone therapy (but only under close supervision).

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