Moderate Weight Loss is associated with Reductions in LH Pulse Frequency and Increases in 24-hour Cortisol with no change in Perceived Stress in Young Ovulatory Women.

OBJECTIVE

Determine the potential role of cortisol as an indicator of both metabolic and psychosocial stress and its relation to LH pulse dynamics during a three-month diet and exercise intervention causing moderate weight loss.

METHODS

Secondary analysis of a randomized controlled trial that demonstrated the causal role of low energy availability in the disruption of the menstrual cycle. Twenty-one women aged 18-24 yrs (BMI 21.7± 1.9 kg·m), completed a baseline menstrual cycle and three intervention menstrual cycles of a controlled diet and supervised exercise program. Twenty-four-hour LH pulse dynamics (q10 min) and diurnal patterns of cortisol (q60 min) as well as Perceived Stress Scale scores were determined in the early follicular phase prior to the intervention and in the post intervention cycle. Pre to post comparisons were determined with paired t-tests, and Pearson bivariate correlations assessed associations.

RESULTS

Subjects lost weight (-2.8±1.97 kg) and LH pulse frequency declined pre=0.79±0.23 pulses·hr to post=0.60±0.29 pulses·hr (p=0.014). Weight loss was associated with an increase in cortisol AUC R= -0.473, (p=0.03) and the decline in LH pulse frequency R= 0.523; (p=0.026). Increases in cortisol AUC were associated with declines in LH pulse frequency R= -0.472; (p=0.048). The morning cortisol rise AUC increased from pre=2140±878 µg·dL · day to post=2556±1067 µg·dL · day (p=0.034). Changes in PSS were not associated with changes in LH or cortisol.

CONCLUSION

The initial perturbation of LH pulsatility with moderate diet and exercise is associated with metabolically driven increases in cortisol AUC with no influence of psychological stress.

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