Sex hormone suppression reduces resting energy expenditure and {beta}-adrenergic support of resting energy expenditure.
Level 4 - case-series / case-control
Single-arm before-after interventional study without a randomized control group.
PubMed 15741268 · doi:10.1210/jc.2004-1344
What was done
Fourteen premenopausal women (mean age 29 ± 5 years) were studied to assess the effect of acute sex hormone suppression on resting energy expenditure (REE). REE was measured via indirect calorimetry in the morning after a 12-hour fast during the midluteal phase of the menstrual cycle and again after 6 days of GnRH antagonist therapy administered during the follicular phase. REE measurements were also performed during beta-adrenergic blockade to quantify sympathetic nervous system (SNS) support of REE.
What was found
GnRH antagonist therapy significantly decreased REE from 1405 ± 42 kcal/d in the midluteal phase to 1334 ± 36 kcal/d after suppression (mean ± SE, P = 0.002). SNS blockade altered REE by -19 ± 10 kcal/d during the midluteal phase compared to 5 ± 11 kcal/d during GnRH antagonist therapy, a trend that was not statistically significant (P = 0.14).
Why it matters
These findings suggest that withdrawal of ovarian sex hormones directly lowers resting metabolic rate, providing a plausible physiological mechanism for the decrease in energy expenditure and weight gain observed during menopause.
Limits
The study is limited by a very small sample size (n = 14) and a non-randomized, uncontrolled before-and-after design. The intervention only lasted 6 days, which may not reflect the long-term metabolic adaptations of natural menopause, and it suppressed both estrogen and progesterone simultaneously, precluding the assessment of their independent effects.
Cited by
- supports Replacing low estrogen can increase energy expenditure by approximately 100 calories per day.