Energy Expenditure and Substrate Utilization During Acute Under- and Over-feeding

Energy Expenditure and Substrate Utilization During Acute Under- and Over-feeding

This study will determine the impact of 24, 48 and 72 hours of over and underfeeding on energy expenditure as measured in the metabolic chamber at the UNC Chapel Hill Nutrition Research Institute (UNC NRI).

Subjects will complete a baseline eucaloric study day. Following this, subjects will be randomized to complete 3 days of overfeeding (150% of baseline eucaloric energy requirements) or 3 days of underfeeding (50% of baseline eucaloric energy requirements). After completing one of these study arms, subjects will cross-over and complete the second arm. All study arms will be separated by two weeks. 24-hour energy expenditure will be measured 3 times during each of 3 day periods. We hypothesize that the impact of over or underfeeding on EE will be evident after 24-hours and will be comparable to 72 hour EE.

Inclusion Criteria:

• Woman
• Postmenopausal
• Aged 50-65 years
• BMI 25-35kg/m2
• Not taking blood pressure or anti-inflammatory medications or any other medications that may impact the results
• Thyroid hormone profile within the normal reference range
• No medical condition which may impact the results (e.g. diabetes)
• Accustomed to eating regular meals including breakfast

Exclusion Criteria:

• Smoker
• Heavy exerciser (defined as >150 minutes/week for more than 3 months)
• Abuses alcohol or drugs
• Vegetarian