Physiological and Psychological Effects of Testosterone During Severe Energy Deficit and Recovery

Inclusion Criteria

• Physically active (at least 2 days per week aerobic and/or resistance exercise)
• Not taking any prescription medications and/or willing to refrain from all medication use prior to and throughout the entire study period, unless provided/approved by the study physician
• Willing to refrain from alcohol, smoking, e-cigarettes, or use of any nicotine product, caffeine, and dietary supplement use throughout the entire study period
• At the discretion of the study physician, wash-out period for medications, supplements, and over-the-counter medications is ≥ 1 to 4 weeks
• Wash-out period for caffeine and alcohol is ≥ 7 days
• Willing to live on the Pennington Biomedical Research Center inpatient unit for 28 consecutive days
• Willing to have a urine drug screening
• Meets age-specific U.S. Army body composition standards according to Army Regulation 600-9, which includes estimates of percent body fat based on height, weight, and circumference measures (neck and waist)
• Total testosterone concentration is within the normal physiological range, total testosterone (300-1,000 ng/dL).

Exclusion Criteria

• Musculoskeletal injuries that compromise exercise capability
• Diagnosed cardiometabolic disorders (i.e., hypertension, hyperlipidemia, kidney disease, diabetes, etc.)
• Allergies or intolerance to foods, vegetarian practices, or history of complications with lidocaine
• Anabolic steroid, human growth hormone, or nutritional testosterone precursor-like supplement use within the past 6 months
• Will not refrain from smoking (any nicotine product), alcohol, caffeine, or any other dietary supplement during the study
• Any use of antibiotics, except topical antibiotics, within 3 months of study participation
• Colonoscopy within 3 months of study participation
• Chronic use of laxatives, stool softeners, antacids, or anti-diarrheal medications (≥ once a week)
• History of gastrointestinal disease (e.g., celiac, irritable bowel syndrome, colitis, Crohn's disease)
• Restrained eater (the Three-Factor Eating Questionnaire) as assessed by the study's psychological and behavioral assessment staff
• Adults unable to consent
• Women
• Prisoners
• Metal implants, claustrophobia, head size incompatible with MRI equipment, etc.
• Sedentary or engages in 150 or diastolic blood pressure > 95 mmHg
• Previous history of breast or prostate cancer
• Previous history of Chronic Obstructive Pulmonary Disease or Obstructive Sleep Apnea
• Findings of lab results of prostate-specific antigen > 3ng/ml, Hematocrit > 50%, or positive urine drug screening
• Based on the investigative team's clinical judgment, a subject may not be appropriate for participation in the study