Aromatase Inhibitors Plus Weight Loss Improves the Hormonal Profile of Obese Hypogonadal Men Without Causing Major Side Effects.
Level 2 - randomized trial
Randomized double-blind placebo-controlled trial
PubMed 32499757 · doi:10.3389/fendo.2020.00277
What was done
A randomized, double-blind, placebo-controlled pilot trial evaluated the efficacy and safety of weight loss (diet and exercise) combined with either the aromatase inhibitor anastrozole (1 mg daily, n = 12) or placebo (n = 11) for 6 months in 23 severely obese men (BMI ≥ 35 kg/m², aged 35–65) with hypogonadotropic hypogonadism (total testosterone < 300 ng/dL, estradiol ≥ 10.9 pg/mL, LH < 9 IU/L). Primary outcomes were hormonal profile, hypogonadal symptoms (questionnaires), and muscle strength (Biodex dynamometer); secondary outcomes included body composition and bone mineral density (DXA), and bone microarchitecture (HR-pQCT).
What was found
Compared to weight loss alone, the anastrozole plus weight loss group had higher testosterone (p = 0.003), lower estradiol (p = 0.001), and greater fat mass reduction (p = 0.04) at 6 months, with no significant differences in lean mass changes. Changes in hypogonadal symptoms and muscle strength did not differ significantly between groups. Total and LDL cholesterol decreased more in the placebo plus weight loss group (p = 0.03 for both). Tibial trabecular bone area decreased more in the placebo group than in the anastrozole group, where it remained stable (p = 0.03). Absolute values, confidence intervals, and effect sizes were not provided in the abstract.
Why it matters
While aromatase inhibition normalizes circulating sex steroids and enhances fat loss during caloric restriction, biochemical improvement in testosterone does not necessarily translate into superior functional or symptomatic benefits over lifestyle-induced weight loss alone in the short term.
Limits
The study is constrained by a very small pilot sample size (n = 23), making it likely underpowered to detect clinical differences in muscle strength or symptom scores. The 6-month duration is insufficient to evaluate long-term bone microarchitecture or cardiovascular outcomes. Absolute numerical values were omitted from the abstract.
Cited by
- supports Aromatase in adipose tissue converts testosterone into estrogen, lowering circulating testosterone levels in obesity.