Energy Expenditure Responses to Different Temperatures
|First Received Date ICMJE||March 30, 2012|
|Last Updated Date||March 14, 2014|
|Start Date ICMJE||March 2012|
|Primary Completion Date||Not Provided|
|Current Primary Outcome Measures ICMJE
||Resting, energy expenditure, heat production, heat loss, thermal neutral zone, environmental temperature, obesity.|
|Original Primary Outcome Measures ICMJE||Not Provided|
|Change History||Complete list of historical versions of study NCT01568671 on ClinicalTrials.gov Archive Site|
|Current Secondary Outcome Measures ICMJE
||Age, sex, race, body temperature, brown adipose tissue, shivering, sweating, hunger, comfort.|
|Original Secondary Outcome Measures ICMJE||Not Provided|
|Current Other Outcome Measures ICMJE||Not Provided|
|Original Other Outcome Measures ICMJE||Not Provided|
|Brief Title ICMJE||Energy Expenditure Responses to Different Temperatures|
|Official Title ICMJE||Energy Expenditure Responses to Different Temperatures|
- 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.
Surprisingly little is understood about how the body regulates heat production (energy expenditure, EE) in response to subtle changes in environmental temperature. For example, only recently has it been realized that brown adipose tissue is functional in adult humans. It is plausible that the mechanisms governing heat production contribute to regulation of body weight and thus may be contributing to the current obesity epidemic: even small changes in EE, if not compensated by changes in food intake, can have long-term effects on body weight.
The thermoneutral zone (TNZ) is the environmental temperature range over which EE is at a minimum and does not change with environmental temperature. The lower and upper critical temperatures define the temperature limits of the TNZ. At environmental temperatures below the lower critical temperature, the EE vs. environmental temperature graph is reported to be a straight line with the extrapolated X-axis intercept being the defended body temperature. Some of these parameters are predicted to be different for obese as compared to lean individuals. With the global obesity epidemic coinciding with improved indoor temperature control, a better understanding of the relationship between EE and thermoregulation is desirable.
This protocol has three phases. The first is a pilot in lean males to optimize procedures and establish the feasibility, sensitivity, and behavior of the assays. Second, lean and obese male cohorts will be compared to ensure that the expected differences can be observed. Third, additional variables will be examined, such as age, race, sex, and menstrual phase in women.
Specifically, we will map the resting EE response to environmental temperatures from 16-31 (Infinite)C during inpatient stays in the NIH Metabolic Clinical Research Unit. Each day resting EE will be measured in a room respiration calorimeter with a different environmental temperature (subjects will be blinded as to room temperature). The remainder of each study day will be spent at 23-25 (Infinite)C in the individual patient room.
Standard diet and physical activity will be maintained and body weight will be held stable. Additionally core body and skin temperatures, heart rate and variability, muscle activity by surface electromyography, and thermal comfort and hunger using visual analog scales will be measured.
This study will establish techniques and provide baseline normative data, allowing insight into the mechanisms regulating the EE in humans and how these are affected by obesity. It is envisioned that this study will provide the basis for investigation of the effects of acute and chronic weight change and the effects of drug therapy.
|Study Type ICMJE||Observational|
|Study Design ICMJE||Time Perspective: Prospective|
|Target Follow-Up Duration||Not Provided|
|Sampling Method||Not Provided|
|Study Population||Not Provided|
|Intervention ICMJE||Not Provided|
|Study Group/Cohort (s)||Not Provided|
* Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
|Recruitment Status ICMJE||Recruiting|
|Estimated Enrollment ICMJE||120|
|Completion Date||Not Provided|
|Primary Completion Date||Not Provided|
|Eligibility Criteria ICMJE||
Blood pressure greater than 140/90 mmHg or current antihypertensive therapy
All subjects will be fully informed of the aims, nature, and risks of the study prior to giving written informed consent.
|Ages||18 Years to 75 Years|
|Accepts Healthy Volunteers||Yes|
|Location Countries ICMJE||United States|
|NCT Number ICMJE||NCT01568671|
|Other Study ID Numbers ICMJE||120097, 12-DK-0097|
|Has Data Monitoring Committee||Not Provided|
|Responsible Party||Not Provided|
|Study Sponsor ICMJE||National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)|
|Collaborators ICMJE||Not Provided|
|Information Provided By||National Institutes of Health Clinical Center (CC)|
|Verification Date||November 2013|
ICMJE Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP