Water Deprivation Protocol
| Status: | Completed |
|---|---|
| Conditions: | Obesity Weight Loss |
| Therapuetic Areas: | Endocrinology |
| Healthy: | No |
| Age Range: | 18 - 50 |
| Updated: | 4/4/2019 |
| Start Date: | October 19, 2010 |
Assessment of Thirst and Role of Water/Electrolytes Homeostasis During Water Deprivation in Obesity
Background:
- One area in which obese and lean individuals may be different is how their bodies handle
water balance and thirst. Studies done in animals suggest that individuals with greater body
fat may tolerate periods without water better than lean animals. Other research has found a
link between the ability to tolerate periods without water and increased body weight.
Researchers are interested in studying whether the ability to tolerate periods without water
and ability to feel thirst might differ in lean versus obese individuals.
Objectives:
- To evaluate the effects of water deprivation and feelings of thirst in lean and obese
individuals.
Eligibility:
- Healthy individuals at least 18 years of age who are either lean (body mass index less than
26 kg/m(2)) or obese (body mass index at least 35 kg/m(2)).
Design:
- Participants will be screened with a medical history, physical examination, and blood
and urine tests.
- Participants will spend the entire study (13 days) as inpatients at the National
Institutes of Health Clinical Center.
- Participants will have the following tests and procedures:
- Body composition assessment (using low-level x-rays) to determine the percentage of fat
tissue in the body.
- Oral glucose tolerance test (similar to that often used to diagnose diabetes).
Individuals who are suspected to have diabetes will not be allowed to continue with the
study.
- High salt infusion test, in which an infusion of saline (salt water) will be given for 2
hours and participants will respond to questions about how hungry and thirsty they feel
during the procedure.
- Water deprivation test, in which participants will go for 24 hours without water or food
and respond to questions about how hungry and thirsty they feel.
- 24-hour stay in a metabolic chamber to determine how many calories participants burn in
a day.
- A series of questionnaires about participants' eating habits, feelings about food, and
personal feelings, as well as computer-based tests involving the performance of various
tasks.
- Measurement of free-living energy using doubly-labeled water, in which participants will
drink a sample of water with extra-heavy atoms of hydrogen and oxygen to evaluate the
amount of water in the body.
- 24-hour urine collection.
- Frequent blood samples, urine collection, and fat tissue biopsies during the various
study procedures.
- After the end of the 13-day study, participants will return after 1 week for a final
urine collection.
- One area in which obese and lean individuals may be different is how their bodies handle
water balance and thirst. Studies done in animals suggest that individuals with greater body
fat may tolerate periods without water better than lean animals. Other research has found a
link between the ability to tolerate periods without water and increased body weight.
Researchers are interested in studying whether the ability to tolerate periods without water
and ability to feel thirst might differ in lean versus obese individuals.
Objectives:
- To evaluate the effects of water deprivation and feelings of thirst in lean and obese
individuals.
Eligibility:
- Healthy individuals at least 18 years of age who are either lean (body mass index less than
26 kg/m(2)) or obese (body mass index at least 35 kg/m(2)).
Design:
- Participants will be screened with a medical history, physical examination, and blood
and urine tests.
- Participants will spend the entire study (13 days) as inpatients at the National
Institutes of Health Clinical Center.
- Participants will have the following tests and procedures:
- Body composition assessment (using low-level x-rays) to determine the percentage of fat
tissue in the body.
- Oral glucose tolerance test (similar to that often used to diagnose diabetes).
Individuals who are suspected to have diabetes will not be allowed to continue with the
study.
- High salt infusion test, in which an infusion of saline (salt water) will be given for 2
hours and participants will respond to questions about how hungry and thirsty they feel
during the procedure.
- Water deprivation test, in which participants will go for 24 hours without water or food
and respond to questions about how hungry and thirsty they feel.
- 24-hour stay in a metabolic chamber to determine how many calories participants burn in
a day.
- A series of questionnaires about participants' eating habits, feelings about food, and
personal feelings, as well as computer-based tests involving the performance of various
tasks.
- Measurement of free-living energy using doubly-labeled water, in which participants will
drink a sample of water with extra-heavy atoms of hydrogen and oxygen to evaluate the
amount of water in the body.
- 24-hour urine collection.
- Frequent blood samples, urine collection, and fat tissue biopsies during the various
study procedures.
- After the end of the 13-day study, participants will return after 1 week for a final
urine collection.
The percentage of people with overweight / obesity in the United States has reached very high
levels, with 65% of adults over the age of 20 being overweight. Recently, there have been a
number of advances in our understanding of the underlying causes of obesity, including
greater understanding of both the effects of the environment and effects that are hereditary
(i.e., genetic).
One area in which obese versus lean individuals may be different is how their bodies handle
water balance and thirst. Studies done in animals suggest that individuals with greater body
fat may tolerate periods without water better than lean animals. Thus, at least in animals,
others have found a link between ability to tolerate periods without water and increased body
weight.
We are studying whether the ability to tolerate periods without water and ability to feel
thirst might differ in lean versus obese individuals. To do so, we will ask lean and obese
individuals to undergo tests that include a period of approximately 24 hours without drinking
any water, and on a separate day a shorter period of an intravenous high salt solution
infusion. We will be looking at how the ability to withstand thirst (dehydration), subsequent
water intake (rehydration), changes in hormone levels during these periods, and behavioral
and physiological responses to thirst and rehydration differ in lean versus obese
individuals. We hope that the data gathered from this study will give us more information
about important differences in how water balance is regulated in lean versus obese
individuals. Understanding these questions may provide new insights into differences between
lean and obese individuals.
levels, with 65% of adults over the age of 20 being overweight. Recently, there have been a
number of advances in our understanding of the underlying causes of obesity, including
greater understanding of both the effects of the environment and effects that are hereditary
(i.e., genetic).
One area in which obese versus lean individuals may be different is how their bodies handle
water balance and thirst. Studies done in animals suggest that individuals with greater body
fat may tolerate periods without water better than lean animals. Thus, at least in animals,
others have found a link between ability to tolerate periods without water and increased body
weight.
We are studying whether the ability to tolerate periods without water and ability to feel
thirst might differ in lean versus obese individuals. To do so, we will ask lean and obese
individuals to undergo tests that include a period of approximately 24 hours without drinking
any water, and on a separate day a shorter period of an intravenous high salt solution
infusion. We will be looking at how the ability to withstand thirst (dehydration), subsequent
water intake (rehydration), changes in hormone levels during these periods, and behavioral
and physiological responses to thirst and rehydration differ in lean versus obese
individuals. We hope that the data gathered from this study will give us more information
about important differences in how water balance is regulated in lean versus obese
individuals. Understanding these questions may provide new insights into differences between
lean and obese individuals.
- INCLUSION CRITERIA:
- Male.
- Age 18-50 yrs to minimize hormonal influences on thirst perception in aging men.
- BMI<25 kg/m(2) for the lean group and BMI greater than 35 kg/m(2) for obese group (but
weigh less than 350 pounds to accommodate the DXA scanner) for the obese group.
- Healthy, as determined by medical history and physical examination, without the
exclusions listed below:
EXCLUSION CRITERIA:
History or Clinical Manifestation of:
- Currently smoking
- Any medications
- Weight less than 50kg (as the blood withdrawal limit would be exceeded)
- Hemoglobin concentration less than 12mg/dl on screening labs
- Type 1 or type 2 diabetes (according to World Health Organization diagnostic criteria
(59))
- Endocrine disorders (Cushing s disease, pituitary diseases, hypo- or hyperthyroidism,
diabetes insipidus, SIADH)
- Hypertension as diagnosed and treated by an outside physician or by sitting blood
pressure measurement, using an appropriate cuff, greater than 140/90 mmHg on two or
more occasions
- Fasting triglyceride concentrations greater than 500 mg/dl
- Cardiovascular disease, including coronary heart disease, heart failure, arrhythmias
and peripheral arterial disease
- Liver disease, including cirrhosis, active hepatitis B or C and AST or ALT greater
than 3 times normal
- Renal disease, as defined by serum creatinine concentrations greater than 1.5 mg/dl
and / or proteinuria greater than 300 mg/day (200 (micro)g/min)
- Central nervous system disease, including previous history of cerebrovascular
accidents, dementia, and neurodegenerative disorders
- Cancer requiring treatment in the past five years, except for non-melanoma skin
cancers or cancers that have been clearly cured or, in the opinion of the
investigator, carry an excellent prognosis
- Infectious diseases such as active tuberculosis, HIV (by self report), chronic
coccidioidomycoses or other chronic infections
- Alcohol and/or current use of drugs (more than 2 drinks per day and regular use of
drugs such as amphetamines, cocaine, heroin, or marijuana)
- Psychiatric conditions or behaviors that would be incompatible with safe and
successful participation in this study, including claustrophobia and eating disorders
such as anorexia or bulimia nervosa
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