Drinking water and weight loss in overweight adolescents

Plain English Summary

Background and study aims
Studies suggest that drinking water can help dieting adults lose weight faster. Drinking water seems to help when adults consume a large amount of drinking water, at least one litre per day, or enough to have dilute (light-colored) urine. Drinking water also seems to help adults most when the weight loss diet is low in carbohydrate.
In addition to not knowing if the effects of drinking water are due to its zero calories and/or its effects on hydration, researchers are not sure if drinking water can help everyone who wants to lose weight.
Weight loss is notoriously difficult for overweight children. Studies are needed to find out (1) if drinking water is an effective way to help overweight children lose weight, and if yes, (2) how much drinking water is necessary, given that children may need a different amount of water than adults.
This study was designed to find out if overweight adolescents can lose weight faster if they drink enough water to have clear urine each day while eating a lower carbohydrate diet.

Who can participate?
Overweight children, who attended information sessions about weight management and/or previously participated in other research studies at
Children’s Hospital Oakland, CA were given information about the study. Children were included in the study if they were overweight, between 9 to 13 years old, regularly drinking beverages like milk, juice, sodas or sports drinks, not already drinking 2L per day water, and willing to have the study foods for 8 weeks.
Potential participants were not included in the study if they had any health condition that could make study participation harmful, such as acute illness, any condition or medication that stimulates anti-diuretic hormone release or promotes weight gain.
Out of 36 boys and girls, who wanted to participate, 28 started the study.

What does the study involve?
Participation in the 8 week feeding study involved weekly clinic visits over 9 consecutive weeks. For 5 days each week, the children wrote down what types of foods they ate at each meal. Each week, study staff measured the children’s body weight, collected a urine and saliva sample, and reviewed what they were eating. For 8 weeks after the first clinic visit, all children were given two bags of commercially available, ready-to-eat salads, soups, fruit, and nuts, with instructions not to eat bread, noodles, rice, potatoes, or other foods that contain flour or sugar. We explained to all of the children that foods that turn into sugar in the blood (like bread, noodles, rice, potatoes, and pastries) make it hard to burn fat, because the body’s rule is to always burn up sugar in the blood first. If you keep the sugar in your blood relatively low, there is more chance to burn fat.
The study participants were randomly assigned to one of two drinking water groups. One group was told to drink only water, no other beverages, because many other beverages contain sugar and result in excess calories. The second group was also told to drink only water, but more specifically, to drink enough water each day to have clear urine by the afternoon. We explained to the second group that yellow pee is a sign that cells are shrinking from not enough water, and when cells shrink they prefer to burn sugar instead of fat.
After the free-food portion of the study ended, the children were invited to come back after 6 months for follow-up assessments.

What are the possible benefits and risks of participating?
This study included assessments that are not generally available through standard care. Participants received multiple weeks of diet, insulin, and hydration assessments, free meals for 8 weeks, and free delivery of bottled drinking water. Study participants benefited by losing weight and learning weight management strategies.
Risks included possible dislike of the study foods, time required for attending the clinic visits and keeping daily study records, and discomfort or embarrassment related to the study foods or drinking water. The children were eating salads that no one else was eating at school. They reported many trips to the bathroom. All study related procedures were non-invasive and did not hurt.

Where is the study run from?
The study took place at outpatient research clinics at the Children’s Hospital & Research Center Oakland, in Oakland CA, USA.

When is the study starting and how long is it expected to run for?
The study happened in two 8 week sessions between September 2010 and June 2011.

Who is funding the study?
The study was funded by Nestle Waters and NIH grants.

Who is the main contact?
Dr. Jodi Stookey
jstookey@chori.org

Contact information

Study information

Eligibility

Locations

Countries of recruitment

• United States of America

Study participating centre

Sponsor information

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Results and Publications