SubsTRate OxidatioN in Girls

Race Differences in 24-hour Energy Expenditure, Substrate Oxidation, and Appetite in Adolescent Girls

This study will examine race differences in total energy expenditure and respiratory quotient (RQ) during and after exercise, compared to a sedentary control condition, in adolescent girls who are classified as overweight. In addition, subjective appetite and objective energy intake will be measured throughout the assessment periods.

Aim 1: Measure 24-hour energy expenditure and its components (resting, activity, and sleep energy expenditure) and compare differences between African-American and White girls.

Hypothesis: Total, resting, and sleep energy expenditure will be lower in African-American relative to White girls. Activity energy expenditure will be equivalent per the study design.

Aim 2: Measure and compare substrate oxidation and associations with appetite (i.e., hunger, desire to eat) and energy intake between African-American and White girls.

Hypothesis: African-American girls will have a higher RQ at rest, during exercise, and following exercise, and RQ will be positively associated with subjective appetite ratings and energy intake.

Inclusion Criteria:

• Female
• Age 13-17 years, inclusive
• Achieved menarche based on parent- and/or self-report
• Overweight based on BMI percentile for age and sex (≥ 85th and < 95th)
• Self-identification as non-Hispanic White or African-American
• Willing to maintain current physical activity, sleep schedule, and dietary habits during the study
• Willing to comply with study procedures

Exclusion Criteria:

• Contraindications to exercise testing as defined by the American College of Sports Medicine (i.e., medical history of cardiovascular, pulmonary, or physical conditions that affect the ability to exercise)
• Food allergies
• Dietary restrictions
• Unwilling to consume study foods
• History of polycystic ovary syndrome (PCOS)
• Current amenorrhea or other menstrual cycle irregularities
• Pregnant or currently breastfeeding
• Current anemia
• Use of medications affecting metabolism or sleep
• Inability to properly or safely complete the study procedures per the investigators' discretion