Chronic Cold Exposure and Energy Metabolism in Humans

Completed

Conditions studied: Healthy

In brief

Background: \- Researchers are studying how metabolism and hormone levels change in response to mild changes in environmental temperature. Changes in metabolism may lessen with time because of hormonal adaptations. If this increase in metabolism continues for a longer period, mild cold exposure may cause weight loss. It is unclear whether exposure to a warmer temperature may cause opposite changes in metabolism. Researchers want to see if longer exposure (1 month) to different temperatures can affect how the body uses energy. Objectives: \- To test changes in energy metabolism in response to different room temperatures. Eligibility: \- Healthy men between 18 and 40 years of age. Design: * The entire study will last for 4 months. It will involve a screening visit and a 4-month inpatient stay at the National Institutes of Health Clinical Center. The inpatient stay will be in a private room at the Metabolic Clinical Research unit. Study participants will be required to stay in the Metabolic Clinical Research unit during the night, but are free to leave during the day. * At the screening visit, participants will have a physical exam and medical history. Blood samples will be collected. A heart function test and diet questionnaire will also be given. * During the first month, the temperature of the private room will be set at to 75.2 degrees F. This will allow the body to become used to the testing environment. * During the second month, the temperature will be set to either a cool (66.2 degrees F) or a warm (80.6 degrees F) temperature. * During the third month, the temperature will return to 75.2 degrees F. * During the fourth month, the temperature will be altered to the opposite temperature to the one set in the second month. * Throughout stay, participants will have daily temperature monitoring and will keep a food diary. Once a week, they will collect all of their urine for 24 hours. Once a month, they will spend 24 hours in a metabolic suite to study their metabolism rate. * Throughout stay, the food will be provided as part of the study. * During the first and third month (75.2 degrees F) the participants will be allowed to leave the Metabolic Clinical Research unit during the weekends, while during the second and forth month (66.2 or 80.6 degrees F), the participants will be allowed to spend one weekend out of the Metabolic Clinical Research unit. * Other tests, such as body scans, fat tissue samples, and imaging studies, will be performed as needed.

Key facts

Study ID

NCT01730105

Run by

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

People needed

7

Starts

2012-11-17

Expected to finish

2018-05-10

Last updated by the study team

2018-05-14

Who can join

Age: 18 and older, up to 40. Sex: male. Healthy volunteers: not accepted.

You may not qualify if…

• Hypo- or hyper-thyroid (history or TSH greater than 5.0 or less than 0.4 milli-international units per liter)
• Blood pressure greater than 140/90 millimeters of mercury (19) or current antihypertensive therapy
• History of cardiovascular disease
• BMI less than or equal to 20 or greater than or equal to 25 kilogram per cubic meter
• Diabetes mellitus or impaired fasting glycemia (fasting serum glucose greater than 100 grams per liter).
• Hypercholesterolemia (serum greater than or equal to 240 levels grams per liter), hypertriglyceridemia (plasma greater than or equal to 220 levels grams per liter) and/or use of antilipemic therapy.
• Liver disease or ALT serum level greater than two fold the upper laboratory reference limit.
• Iron deficiency (Ferritin less than 40 nanograms per milliliter males) (20).
• Renal insufficiency or estimated creatinine clearance less than 50 milliliter per minute (MDRD equation).
• Claustrophobia.
• History of illicit drug or alcohol abuse within the last 5 years; current use of drugs (by history) or alcohol (CAGE greater than 3).
• Psychiatric conditions or behavior that would be incompatible with safe and successful participation in this study
• Current use of medications/dietary supplements/alternative therapies known to alter thyroid function.
• Current use of antiplatelet or anticoagulants.
• Allergy to lidocaine.
• Current smoker or user of tobacco products
• Current participation in weight loss programs (dietary, exercise or pharmacological) or more than 3 kg weight changes in last 6 months
• Spending greater than 70% daily hours outdoors

Where it is running

• National Institutes of Health Clinical Center, 9000 Rockville Pike — Bethesda, Maryland, United States

Full record on ClinicalTrials.gov

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