A randomized, cross over study will assess the effects of ingestion of high and low volumes of water on REE over 90 minutes. The high volume of water 500ml and the low volume of water 250ml. Participants will be computer randomized to determine which volume of water to receive first. Participants will arrive at the Nutrition Assessment Laboratory between 7:00 and 7:30am following a 9 hour overnight fast. Participants will be instructed not to consume any food or drink after 10pm the night before the assessment. Participants will also be asked to abstain from alcohol and caffeine for 3 days before the assessment. After verification of eligibility, baseline REE will be measured for 30 minutes followed by administration of first assigned dose of water. REE will be monitored for the next 90 minutes. Blood pressure and heart rate will also be monitored, simultaneously to REE. After a 7-10 day washout period, participants will return for their second test day where the second dose of water will be administered. A 7-10 day washout period was selected to allow participants time to resume normal diet and hydration between visits.

Inclusion Criteria:

• 18-39 years of age
• Generally Healthy men and women
• BMI 18.5-28
• Willing to abstain from caffeine for 3 days prior to testing
• Able to provide written consent in English
• Ability to communicate in English (oral and written

Exclusion Criteria:

• <18 or >39 years
• BMI < 18.5 or >28
• Pregnant or Nursing
• Taking prescribed or over the counter medication affecting fluid balance or metabolism
• Suffers from hepatic, renal, pulmonary, endocrine or hematological disease
• Performs more than 3 hours a week of strenuous exercise
• Consumes, on average, more than 2 alcoholic beverages per day
• More than 5kg of weight change over the past 6 months
• Claustrophobic