(OR20-04-25) Using RMR Ratio to Identify REDs Risk Among Female Athletes

Objectives: Female athletes are at risk of Relative Energy Deficiency in Sport (REDs) if energy intake is insufficient relative to demand. REDs is commonly identified via low energy availability (EA), which is determined by measuring dietary intake, exercise energy expenditure, and lean body mass. Due to inconsistent methods to measure each component of EA, the use of resting metabolic rate (RMR) ratio is proposed as an alternate method to identify REDs. The purpose of this study was to identify REDs prevalence among a sample of physically active college-aged females using RMR ratio, and correlate this with Energy Availability.

Methods: Females (18-24 years) who were members of a NCAA Division 1 athletics team or highly physically active (greater than 4 days/week) participated in the study. Body composition was measured using air displacement plethysmography. Resting metabolic rate was measured using indirect calorimetry. Participants reported dietary intake via a 24-hour recall for 1-3 days. EA was calculated using an averaged activity factor of 1.67 to determine exercise energy expenditure. RMR was calculated using standard equations (Harris-Benedict, Owen, Cunningham).

Results: A total of 77 physically active female college students participated, including 53 NCAA Division 1 athletes. Mean EA was 24.5 ± 12.8 kcal/kg fat-free mass (FFM)/day and 63% of participants met criteria for low EA ( < 30 kcal/kg FFM/day). Mean RMR ratio was 1.08 ± 0.16 with 19% of the sample having low RMR ratio (below 0.9). Overall, 14% of participants had both low EA and low RMR ratio. There were no differences in EA or RMR ratio between the collegiate athlete and recreational athlete groups.

Conclusions: Physically active female college students, including collegiate athletes, exhibited sub-optimal EA. Low RMR ratio appeared to be a more sensitive indicator of REDs risk than low EA.

Funding Sources: Academy of Nutrition and Dietetics Foundation (Vegetarian Nutrition Dietetic Practice Group) and the Atlantic Coast Conference.