DLW Energy Expenditure

Doubly Labeled Water (DLW) provides an assessment of a participant’s total energy expenditure (TEE).

TEE is assessed by lab analysis of urine collected at several time points, looking for rates of elimination of two heavy atoms, deuterium and oxygen-18. After a loading dose of doubly labeled water (a mixture of deuterium and oxygen-18), deuterium is eliminated from the body as water and oxygen-18 as both water and carbon dioxide. The difference between the elimination rates provides a measure of carbon dioxide production. Carbon dioxide is the end product of energy metabolism and so provides a measure of energy expenditure.

The DLW measurement protocol involves the administration of the labeled water and collection of urine specimens on two days separated by two weeks. Participants consume dosing water at a clinic visit and provide 1 pre- and 3 post-dose urine samples. They are provided with materials to collect 2 additional urine samples at home on the day two weeks after the clinic visit.

The DLW protocol was initiated in the Study Center (at Clinic Visit 1 for Groups 1 and 3, and at Clinic Visit 2 for Groups 2 and 4). For a subsample of participants, the protocol was repeated at the Study Center approximately 6 months after the initial clinic visit (i.e., at Clinic Visit 2 for subsample participants in Groups 1 and 3 and at Clinic Visit 3 for subsample participants in Groups 2 and 4).

Click here for data dictionaries and formats for the DLW Energy Expenditure files. Datasets can be obtained by submitting a request.

Urine Collections

Urine samples in a 24 hour period were collected at home by participants. The 24 hour period started with first urination of the morning. Couriers picked up the samples and delivered to the clinic. The urine samples were then analyzed for nutrients and metabolic profiles. Average Potassium, Sodium and Nitrogen results were provided.

Click here for data dictionaries and formats for the Urine Result files. Datasets can be obtained by submitting a request.

Saliva

The Saliva Collection Form collects data about the timing and medication being taken during the saliva sample collection. Participants were asked to provide saliva samples twice during the study with six months between administrations.

Saliva collection form data is provided in one format: 1 record per person containing both collection forms.

Click here for data dictionaries and formats for the Saliva Collection Form files. Datasets can be obtained by submitting a request.