Dietary restriction reduces luteinizing hormone (LH) pulse frequency during waking hours and increases LH pulse amplitude during sleep in young menstruating women.

Abstract

To determine the effect of dietary energy restriction on gonadotropins, we assayed LH and FSH in samples drawn at 10- and 60-min intervals, respectively, over 24 h from seven young women (mean +/- SE gynecological age, 7.7 +/- 1.2 yr) on day 9, 10, or 11 of two menstrual cycles. Cortisol was measured in samples collected at 30-min intervals. During the 4 previous days and the day of sampling, dietary energy intake was set at either 45 or 10 Cal/kg lean body mass.day in random order. Beginning 2 days before treatment, blood was sampled daily at 0800 h and assayed for T3, insulin-like growth factor-I, and insulin. Estradiol was measured in samples collected daily and at 6-h intervals on the day of frequent sampling. By the day of frequent sampling, dietary restriction had reduced T3 20% (P < 0.01), insulin-like growth factor-I 58% (P < 0.001), and insulin 54% (P < 0.001). Twenty-four-hour transverse means for LH (P = 0.3), FSH (P = 0.2), estradiol (P = 0.3), and cortisol (P = 0.13) were unaffected, but LH pulse frequency was reduced 23% (P < 0.01), especially during waking hours, whereas LH pulse amplitude was increased 40% (P = 0.05), especially during sleep. These results support the hypothesis that LH pulsatility depends upon energy availability in women, as it does in other mammalian species.

Differential regulation of metabolic, neuroendocrine, and immune function by leptin in humans

“…Partial restoration of leptin levels with r-metHuLeptin during 4-day fasting was associated with a decrease in overnight LH pulses in normalweight women, but fed-state leptin levels were not reached (23). Potential effects of r-metHuLeptin may have been obscured by interindividual differences, which our study and others (19,20,24,25) have minimized by studying the same subjects under different conditions at the same times of their menstrual cycles.…”

“…Although follicle development was not directly evaluated, the maintenance of normal menstrual cycles argues against substantial disruption of follicular growth and ovulation. Interestingly, normal-weight women have decreased LH pulse frequency during short-term starvation despite maintaining ovulatory cycles in several (19,20) but not all (21-23) studies. Partial restoration of leptin levels with r-metHuLeptin during 4-day fasting was associated with a decrease in overnight LH pulses in normalweight women, but fed-state leptin levels were not reached (23).…”

Female athletes and health

“…On the other hand, some data suggested that no relationship existed between body fat and reproduction, since no differences in adiposity were noted between eumenorrheic and amenorrheic female runners [32,51]. However, a close association was shown between a disturbed sex hormonal profile and low energy availability (energy intake reduced by energy expenditure) in women who engaged in strenuous physical activity [31,34,63]. Interestingly, deteriorations in the LH and FSH secretions similar to those observed in female athletes were observed in sedentary women with eating disorders, such as bulimia nervosa [29,49].…”

Leptina: aspectos sobre o balanço energético, exercício físico e amenorréia do esforço

“…Estima-se que a ocorrência de amenorréia exista em 30 a 50% das bailarinas profissionais, 50% das corredoras competitivas, 25% das corredoras não competitivas e 12% das nadadoras e ciclistas. Ginastas, tendo seu estado nutricional avaliado, demonstraram baixo percentual de gordura e retardo no aparecimento dos caracteres sexuais (82,83). É importante ainda destacar estudos prospectivos que demonstraram a existência de alterações ovulatórias subclínicas em mulheres que praticam exercícios de forma recreativa.…”