Hydration & Female Life Stages

Effect of Female Life Stage on Rehydration With Water vs. an Electrolyte Solution After Overnight Fast/Fluid Restriction

Female life stages including premenopausal, perimenopausal, postmenopausal, are characterized by changing concentrations and patterns of hormones. The premenopause stage represents the reproductive years with normal menstrual cycles lasting between 21-35 days. The perimenopause stage is the beginning of the menopause transition and can last up to 10 years. During this transition, menstrual cycles become longer and irregular in length (7 days or longer). After 12 consecutive months with no period, the transition is complete into the postmenopause stage.

Hormones that change across the lifespan are known to influence systems that regulate thirst, fluid balance, and sodium balance. Yet, fluid balance across life stages remains poorly understood, with no direct comparisons across all three life stages. The purpose of this study is to evaluate the effect of female life stage on rehydration with water and electrolyte solution after overnight fast and fluid restriction

Study Overview

• Status: Recruiting
• Conditions: Dehydration; Menstruation; Hydration; Post-menopausal Women; Peri-menopausal Women; Pre-menopause
• Intervention / Treatment: Other: placebo beverage; Other: electrolyte beverage

• Study Type: Interventional
• Enrollment (Estimated): 72
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Samantha Goldenstein; Phone Number: 847-707-3118; Email: GatoradeGSSIIMG@pepsico.com
• Study Contact Backup: Name: Susan Kwiecien; Phone Number: 847-707-3118; Email: GSSIresearchstaff@pepsico.com

Study Locations

• United States
  • Florida
    • Bradenton, Florida, United States, 34210
      • Recruiting
      • GSSI Bradenton
      • Contact: Samantha Goldenstein; Phone Number: 847-707-3118; Email: GatoradeGSSIIMG@pepsico.com
  • New York
    • Valhalla, New York, United States, 10595
      • Recruiting
      • GSSI Valhalla
      • Contact: Susan Kwiecien; Phone Number: 847-707-3118; Email: GSSIresearchstaff@pepsico.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• • Sex assigned female at birth.

  • Recreationally active (engaged in light to moderate-intensity, intermittent, or steady-state exercise at least 3 days per week for at least 30 min at a time)
  • Age 18-60 years, within the following life stage ranges specified below:

  • Premenopausal:

    • 18-35 years
    • Self-report regular spontaneous menstrual cycle length (21-35 days) for the past 2 menstrual cycles
    • Menstrual cycle length < 7 days variation in consecutive cycles

  • Perimenopausal:

    • Perimenopause: 35-55 years
    • If tracking cycles: self reported cycle irregularity (≥7 day difference from usual cycle length) for the past 2 menstrual cycles, not due to known pathology
    • If not tracking cycles: clinician diagnosis

  • Postmenopausal:

    • Postmenopause: 45-60 years
    • If tracking cycles: ≥12 consecutive months of spontaneous amenorrhea not due to pregnancy, lactation, or pathology
    • If not tracking cycles: clinician diagnosis
  • Healthy, with no known renal, cardiovascular, metabolic, or endocrine disorders that affect hydration or fluid regulation.

  • Not currently taking medications known to influence fluid balance (e.g., diuretics, laxatives, weight loss agents, or other relevant medications) or the hypothalamus-pituitary-gonadal axis (e.g., ovulation induction agents, gonadotropins, IVF stimulation medications, or other relevant medications)

    o See appendix 13.8 for list of medications, drugs, and/or medical conditions that may impair cognitive functioning, alter physiological responses relevant to the study outcomes, or increase the risk associated with participation.

  • Not receive any fertility treatments within the past 6 months
  • No hormonal contraceptives use within the past 6 months
  • If using a paraguard copper IUD, it must be inserted for ≥ 3 months (if applicable)
  • BMI ≤ 30 kg/m²
  • Are not participating in a weight loss program
  • Are not allergic to adhesives, stevia, and strawberry lime flavoring
  • Willing to avoid strenuous activity and alcohol consumption 24 hours prior to all visits
  • Willing to fast overnight (~12 hours) prior to the medical screening

  • For visit 2 and 4:

    • Willing to fast overnight (~12 hours)
    • Willing to consume a minimum of 2.7 L of water 24 hours prior to visits 2 and 4, then 500 mL 2 hours before the start of the visits 2 and 4
  • For visits 3 and 5:
  • Willing to restrict all fluids (~18 hours)
  • Willing to limit fluid consumption to 1 L the morning/afternoon prior to the start of the fluid restriction
  • Willing to restrict food (~12 hours) the day prior to each visit Willing to eat a consistent diet the day prior
  • Fluent in English (able to read, understand, and provide informed consent).
  • Willing and able to provide informed consent to participate in the study and comply with all study procedures and scheduled visits

Exclusion Criteria:

• • Currently pregnant or breastfeeding

  • < 6 months since giving birth (even if experiencing 2 regular menstrual cycles in a row)
  • Smoking within the last 5 years
  • History of adverse events (e.g., fainting) with blood draws
  • Participants with large amount of internal metal (e.g., spinal rod) will be excluded from the DXA scan only (Brandenton)
  • Participant has participated in a clinical trial within the past 30 days
  • Participant has participated in any PepsiCo trial within past 3 months
  • Participant has a condition or is taking medication that the investigator believes would interfere with his/her ability to provide informed consent, comply with the study protocol, which might confound the interpretation of the study results, or put the person at undue risk
  • Participant is employed by, or has a parent, guardian, or other immediate family member employed by a company that manufactures any products that compete with any Gatorade product. If participant is unsure if a company would be considered a competitor to Gatorade, they will be asked to please let the study investigator know the name of the other company and the nature of their relationship to that company before they sign the informed consent.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo Beverage	Other: placebo beverage; 333 mL aliquots 3 times for a total of 1 L over a 30 min period. Time 0 begins post-dose.
Experimental: Electrolyte Beverage	Other: electrolyte beverage; 333 mL aliquots 3 times for a total of 1 L over a 30 min period. Time 0 begins post-dose. Beverage matched to placebo for color and flavor.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fluid Balance	calculated as change in nude body mass from baseline (%)	Change from baseline, 4 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fluid Balance	calculated as change in nude body mass from baseline (g)	Change from baseline, 4 hours
Urine Mass	g	Change from baseline, 4 hours
Urine Specific Gravity	au	Change from baseline, 4 hours
Urine Osmolality	mosmol/kg	Change from baseline, 4 hours
Fluid Retention	Percentage (%)	Change from baseline, 4 hours
Free Water Clearance	ml/min	Change from baseline, 4 hours
Whole blood sodium concentration	mmol/L	Change from baseline, 4 hours
Whole blood potassium concentration	mmol/L	Change from baseline, 4 hours
Whole blood glucose concentration	mg/dl	Change from baseline, 4 hours
Whole blood hematocrit	Percentage (%)	Change from baseline, 4 hours
Whole blood hemoglobin concentration	g/dl	Change from baseline, 4 hours
Serum osmolality	mosmol/kg	Change from baseline, 4 hours
Serum copeptin concentration	pmol/L	Change from baseline, 4 hours
Serum estrogen	pg/mL	Change from baseline, 4 hours
Serum progesterone	ng/mL	Change from baseline, 4 hours
Serum follicle stimulating hormone (FSH)	pg/mL	Change from baseline, 4 hours
Capillary follicle stimulating hormone (FSH)	MIU/mL	At baseline, to determine menstruation status
Salivary Cortisol	ng/mL	Change from baseline, 4 hours
Salivary Estradiol	pg/mL	Change from baseline, 4 hours
Salivary Progesterone	pg/mL	Change from baseline, 4 hours
Low energy availability Questionnaire (LEAF-Q)	Validated questionnaire that assesses injury, gastrointestinal symptoms, and menstrual function, score > 8 at risk for LEA	at screening to determine menstrual history
Menopause Rating Scale (MRS)	5-point likert scale assessing symptoms as none (0) to very severe (4), > score mean more severe/greater number of symptoms	at baseline to determine menopause symptoms
Feeling Scale (FS)	11-point scale assessing changes in mood ranging from very good (5) to very bad (-5), positive score is associated with positive affect	change from baseline, 4 hours
Gastrointestinal discomfort and headache (VAS)	100-pt visual analog scale anchored from none (0) to severe (100), > score is associated with increased symptoms	change from baseline, 4 hours
Mental and physical energy and fatigue (VAS)	100-pt visual analog scale anchored from none (0) to severe (100), > score is associated with stronger feelings	change from baseline, 4 hours
Blood Pressure	systolic/diastolic, mm/Hg	Change from baseline, 4 hours
Heart Rate	Beats per minute (BPM)	Change from baseline, 4 hours
Adverse Events	Documented changes in health and symptoms as a safety measurement	Through study completion, an average of 4 weeks for pre- and peri-menopausal subjects and 2 weeks for post-menopausal subjects.

Collaborators and Investigators

• Sponsor: PepsiCo Global R&D

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): November 1, 2026
• Study Completion (Estimated): December 1, 2026

Study Registration Dates

• First Submitted: June 12, 2026
• First Submitted That Met QC Criteria: June 12, 2026
• First Posted (Actual): June 17, 2026

Study Record Updates

• Last Update Posted (Actual): June 17, 2026
• Last Update Submitted That Met QC Criteria: June 12, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pathologic Processes; Metabolic Diseases; Water-Electrolyte Imbalance; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Dehydration
• Other Study ID Numbers: PEP-2604

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No