Energy Expenditure Responses to Different Temperatures

Completed · Not applicable

Conditions studied: Obesity, Normal Physiology

In brief

Background: \- The way that the body burns calories is known as energy expenditure. Some studies show that when we are cold, we burn more calories to keep our bodies warm. Brown fat is a special kind of fat that can use energy to keep the body warm. Small animals and infants have been known to have brown fat for many years. Recently, it has been suggested that adult humans also have brown fat. If brown fat becomes active (burns calories) in adult humans when exposed to cold, then these people would tend to burn off more calories and might not gain weight easily. Learning more about the relationship between energy expenditure, brown fat, environmental temperature, and body temperature may help explain why some people become obese and other people do not. Objectives: * To better understand how the body burns calories when exposed to different temperatures. * To study brown fat and how it burns calories in cold temperatures. Eligibility: * Healthy men between 18 and 35 or 55 and 75 years of age. * Healthy women between 18 and 35 years of age. * To control for ethnicity, participants must be non-Hispanic whites or African Americans. Design: * Participants will be screened with a physical exam and medical history. Blood and urine samples will be collected. * Participants will stay in the Metabolic Unit of the National Institutes of Health Clinical Center as inpatients for no more than 14 days. The length of the hospital stay will depend on how participants respond to the different study temperatures. * Every afternoon, participants will walk for 30 minutes on a treadmill. All meals will be provided. * Participants will stay up to 5 hours per day in a specialized room with different temperature settings. Temperatures will range from about 61 degrees to 88 degrees Fahrenheit. Body temperature, activity, calorie burning, and cold/hot sensations will be monitored. On the study day of the coldest temperature, participants will have an imaging study to look for brown fat activity. * Participants will be compensated for their time and participation at the end of the study....

Key facts

Study ID

NCT01568671

Run by

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

People needed

104

Starts

2012-04-24

Expected to finish

2019-11-14

Last updated by the study team

2026-08-04

Who can join

Age: 18 and older, up to 75. Sex: any. Healthy volunteers: accepted.

You may not qualify if…

• Hypo- or hyper-thyroid (history or TSH >5.0<0.4 miU/L)
• Psychological conditions,such as (but not limited to) claustrophobia, clinical depression, bipolar disorders, that would be incompatible with safe and successful participation in this study
• Weight change >5% in the past 6 months or a trained athlete
• Blood pressure greater than 140/90 mmHg or current antihypertensive therapy
• History of cardiovascular disease
• BMI <18.5, between 25.1-29.9, and >40 Kg/m(2)
• Diabetes mellitus (fasting serum glucose > 126 mg/dL)
• Liver disease or ALT serum level greater than two times the laboratory upper limit of normal
• Iron deficiency (Ferritin < 30 mcg/L males, < 15 mcg/L females)
• Abnormal kidney function (eGFR<60 ml/min/1.73m(2))
• History of illicit drug or alcohol abuse within the last 5 years; current use of drugs (by history) or alcohol (CAGE greater than or equal to 2)
• Current use of medications/dietary supplements/alternative therapies known to alter energy metabolism
• Pregnancy/breastfeeding/hormonal contraception or childbirth within the last year
• Perimenopausal (as self-described within two years from onset of amenorrhea or current complaints of hot flashes)
• For pre-menopausal women, irregular periods or polycystic ovarian disease
• Current smoker or user of tobacco products
• Metal implant that prevents subject from being in a MRI scanner.
• All subjects will be fully informed of the aims, nature, and risks of the study prior to giving written informed consent.

Where it is running

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

Full record on ClinicalTrials.gov

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