The translation of the national CATCH program to low-income schools with Hispanic students successfully slowed the epidemic increase in risk of overweight or overweight seen in control school children. An emphasis should be placed on community organizing and evaluation feedback when implementing evidence-based school health programs in low-income Hispanic communities.
To investigate the relationship between energy availability (dietary energy intake minus energy expended during exercise) and thyroid metabolism, we studied 27 untrained, regularly menstruating women who performed approximately 30 kcal.kg lean body mass (LBM)-1.day-1 of supervised ergometer exercise at 70% of aerobic capacity for 4 days in the early follicular phase. A clinical dietary product was used to set energy availability in four groups (10.8, 19.0, 25.0, 40.4 kcal.kg LBM-1.day-1). For 9 days beginning 3 days before treatments, blood was sampled once daily at 8 A.M. Initially, thyroxine (T4) and free T4 (fT4), 3,5,3'-triiodothyronine (T3) and free T3 (fT3), and reverse T3 (rT3) were in the normal range for all subjects. Repeated-measures one-way analysis of variance followed by one-sided, two-sample post hoc Fischer's least significant difference tests of changes by treatment day 4 revealed that reductions in T3 (16%, P < 0.00001) and fT3 (9%, P < 0.01) occurred abruptly between 19.0 and 25.0 kcal.kg LBM-1.day-1 and that increases in fT4 (11%, P < 0.05) and rT3 (22%, P < 0.01) occurred abruptly between 10.8 and 19.0 kcal.kg LBM-1.day-1. Changes in T4 could not be distinguished. If energy deficiency suppresses reproductive as well as thyroid function, athletic amenorrhea might be prevented or reversed by increasing energy availability through dietary reform to 25 kcal.kg LBM-1.day-1, without moderating the exercise regimen.
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.
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