Influence of Flavonoids and Caffeine Supplementation on Resting Metabolism

- Women, ages 20 to 47 years

- Body mass index (BMI) between 18.5 and 33 kg/m2 (normal weight, overweight, mild obesity)

- Weight during the past 6 months has been somewhat stable (+/- 12 lbs)

- Low-to-moderate caffeine intake, defined as consuming on average: less than 3 servings per day of coffee (each about 8 fl. oz.) and/or energy drinks with caffeine; less than 3 soft drinks with caffeine and tea per day

- Premenopausal (self-report)

- Willingness to maintain habitual diet and physical activity patterns, and not lose weight throughout the study period

- Understands and agrees to all study procedures and signs the form providing informed consent to participate in the study

- Willingness to report and maintain normal schedule of hormonal therapy including oral contraceptive pills, hormonal IUD, Nuva Ring, or DepoProvera injections.

- Normal thyroid function as determined from a blood sample collected during pre-study baseline testing.

- Not pregnant as determined by a urine pregnancy test during pre-study baseline testing and prior to the second chamber session, and not planning to become pregnant during the study.

- Willingness to avoid vigorous exercise the day before each metabolic chamber session (e.g., intense running, cycling, swimming for 30 minutes and longer).

- Taking medications for or suffering from a medical condition that may impact results related to metabolism (e.g. thyroid disorders, diabetes, mental disorders such as anxiety or depression, heart disease, arthritis, cancer).

- Heavy exerciser (defined as more than 300 minutes per week of moderate to vigorous exercise within the last two weeks)

- Thyroid hormone levels outside of the normal laboratory reference range

- Pregnant or lactating, or planning to become pregnant during the study

- Recent use of antibiotics (within last two weeks)

- History of smoking during the six months prior to study

- Recent signs or symptoms of infection, including cold or flu-like symptoms (within last 2 weeks)

- Conditions or diseases the investigator believes would interfere with ability to provide consent, comply with the study protocol, which might confound the interpretation of the study results or put the person at undue risk. These include the disease list above and other health problems that would make it difficult to comply with two 24-hour periods of confinement in the metabolic chamber such as panic disorder, cardiac arrhythmias, musculoskeletal disorders such as low back pain and osteoarthritis, and gastrointestinal disorders including reactions to supplements with caffeine and vitamin C, and food allergies.

- Inability or unwillingness to consume the foods that will be included in the provided meals when staying in the chamber

- History of drug or alcohol abuse (>5 standard drinks per day)

- Taking herbal supplements or medications that may influence metabolism within 14 days prior to the study, including supplements containing bitter orange, guarana, fucoxanthin, and green coffee bean, and medications such as Meridia, Xenical, LipoRidAM, Advantra-Z, NuPhedrine, and Slim-10.

- Current consumption (or unwilling to stop intake 2 weeks prior) of flavonoid supplements, or a heavy consumer of green tea (>3 cups per day)

- Near-daily use of tablets containing caffeine (e.g., NoDoz) (or unwillingness to stop 2 weeks prior to the study).

- High intake of caffeine from coffee, tea, energy drinks with caffeine, and soft drinks containing caffeine (or unwillingness to reduce intake for 2 weeks prior to the study and during the 4-week study).

- Prone to panic attacks when confined in a small room, especially when consuming caffeine.