Effect of One Month Exposure to Components of Reprometabolic Syndrome on Physical Activity & Body Composition in Lean Women

Abstract

Abstract Background: Subfertility in obese women is associated with chronic pituitary suppression, reduced sensitivity to GnRH and decreased sex steroid production. We have found evidence for a combined effect of hyperinsulinemia and high circulating fatty acids to acutely (4h infusion) suppress pituitary gonadotropin secretion and are currently investigating the effects of one-month exposure to a eucaloric high-fat diet (HFD) on gonadotropin levels in lean women. The aim of this study is to examine the effect of the one-month HFD on physical activity and body composition. Methods: 12 normal weight (BMI < 25 kg/m2), normally cycling female participants of reproductive age were given a one-month eucaloric HFD, from the onset of menses in one cycle through the next, with 48% calories from fat. A Fitbit was provided to monitor changes in daily activity and sleep throughout the study. Measurement of gonadotropin pulsatility and reproductive hormones were done using frequent blood sampling and daily urine excretion, respectively. These measurements were obtained for a total of 4 menstrual cycles: 1 pre-diet cycle, the HFD cycle, and 2 post-diet cycles. DEXA body composition was measured at baseline and at the end of the 2nd post diet cycle. Pre and post diet comparisons were done using linear mixed model testing and reported as estimated means ± standard error. Results: Mean number of daily steps were (9,226 ± 1,140) pre diet, (9,132 ± 1,140) during the diet and (7,533 ± 1,140) post diet. Daily active calories were (1,982 ± 99) pre diet, (1,975 ± 99) during the diet and (1,856 ± 99) post diet. Means in the HFD cycle did not differ from the pre-diet cycle. Daily sleeping minutes pre diet were (443 ± 19), (451 ± 20) during the diet and (412 ± 19) post diet, with no statistical difference between the 3 time points. BMI did not differ between pre-diet (21.84 ± 0.52) and post-diet (21.77 ± 0.52). DEXA body composition measurements indicated a statistically significant decrease in total fat percentage, (32.26 ± 1.53) pre diet and (31.31 ± 1.53) post diet, which does not appear clinically significant as the difference of less than 1% falls within the anticipated measurement error of the method. Visceral fat volume (cm3) did not differ between pre diet (299.51 ± 27.76) and post diet (295.53 ± 27.76). Conclusions: The complete cohort has not yet been fully recruited and analyzed. These preliminary findings indicate that women consuming a one-month, HFD maintain their usual level of physical activity and sleep patterns, and do not appear to sustain change in visceral fat. Further accrual of participants should clarify the small decrease in total body fat observed without a change in BMI. Supported by HD087314 ROI to NS UL1TR002535 to the Colorado Clinical and Translational Sciences Institute.