TITLE:
Consumption of Two Eggs Daily Increases Serum Leptin in Amenorrheic Runners with Low Energy Availability without Changes in Lipid Profile
AUTHORS:
Lyra Clark, Michael Dellogono, Thomas A. Wilson
KEYWORDS:
Endurance Training, Running, Cholesterol, Estrogen, Leptin
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.17 No.2,
February
9,
2026
ABSTRACT: Background/Objective: Low energy availability (EA) occurs in athletes due to inadequate dietary intake to meet the energy expenditure during exercise. A detrimental consequences of low EA in female athletes is suppression of menstrual function leading to chronic hypoestrogenism, which may reduce bone mass while elevating the risk of injury. The primary aim of this study was to investigate the effects of increased dietary cholesterol intake through the consumption of eggs on ovarian sex hormone and leptin levels in amenorrheic female endurance athletes. Methods: Division I female distance runners classified as amenorrheic (AMEN, n = 5) or eumenorrheic (EUMEN, n = 5) via self-report questionnaire participated in this study. Participants consumed two eggs per day for 12 weeks over the course of the outdoor track and field season. EA was calculated at baseline and post-intervention using 3-day dietary records, triaxial accelerometers, and heart rate (HR) monitors. Maximal oxygen uptake (VO2max) was measured to calculate exercise energy expenditure with training HR data. Serum hormones, body composition, and blood lipids were measured at baseline and post-intervention. Results: There were no significant differences exhibited between the AMEN and EUMEN groups in body composition, EA, or sex hormones at baseline and after the dietary intervention. However, when examining differences within groups between baseline and post-intervention, serum leptin levels increased in the AMEN group by 70% (p = 0.02) compared to baseline following egg consumption, while no change in serum leptin was observed in the EUMEN group. Also, at baseline, EA was calculated to be below 30 kcal·kg−1·FFM·d−1 threshold for only the AMEN group, while the EUMEN group was right at the threshold, whereas post-intervention, EA was calculated to be below the threshold in both groups, but not significantly when compared to baseline. Importantly, no changes in serum lipids and lipoprotein cholesterol levels were observed in either treatment group post-intervention with the consumption of eggs compared to baseline. Conclusions: Twelve-week consumption of two eggs per day increased serum leptin in amenorrheic athletes with low EA, with no changes in ovarian sex hormones. The serum lipid profile was not adversely affected by increased dietary cholesterol in the form of eggs.