Body Heat Content and Dissipation in Obese and Normal Weight Adults
This study will investigate how different parts of the body lose body heat and will measure the heat released by specific areas such as the limbs and abdomen. Animal studies suggest that dissipation of body heat may affect energy expenditure, and therefore, body weight. This study will explore the relationship between obesity and heat in humans.
Healthy people 18 years of age and older who are of normal weight or who are obese and who are not taking medications for obesity-related medical conditions may be eligible for this study. Candidates must have a body mass index (BMI) between 18 and 25 kg/m2 for normal weight subjects or a BMI greater than 30 kg/m2 for obese subjects. All candidates must weigh less than 300 pounds. Women must have a normal menstrual cycle or be postmenopausal.
Participants undergo the following procedures in a single day on an outpatient basis:
- Medical history, physical examination, blood and urine tests and electrocardiogram.
- DEXA and MRI scans of the trunk and limbs to measure the amounts of muscle, bone and fat in the body. For the DEXA scan, the subject lies on a table while a very small dose of x-rays is passed through the body. For the MRI, the subject lies on a table that is moved into a steel cylinder. A magnetic field and radio waves produce images that are used to measure fat in the trunk of the body, thighs, and arms.
- Infrared photography of hands, front of thigh, and abdomen. A special camera is used to measure the heat leaving the body.
- Bicycle exercise test. The subject exercises on a stationary bicycle while the heart rate, heart rhythm, blood pressure and oxygen consumption are measured. The pedal resistance is increased gradually until the subject can no longer exercise and then the resistance is gradually decreased for cool-down.
Participants who qualify for the second part of the study undergo the following procedures during a 5-day in-hospital stay:
- Temperature measurements. Body temperature is measured in the ear canal. Skin temperature is measured with small round adhesive temperature-sensing patches placed on the abdomen and limbs for up to 5 days.
- Measurement of body radiowaves. A remote sensing device is used to measure microwaves that are naturally released from the body.
- Infrared photography of hands, front of thigh and abdomen is done several times during the study.
- Application of mild coolness to hands, thigh and abdomen. The subject's hand is exposed to mild coolness first by immersion in cool water, then by a cool-water spray, then by a cooled pad placed on the hand, and finally, with a device applied to the hand that cools and has a gentle vacuum. The abdomen and thigh are similarly exposed. During each test, an infrared camera records how heat is released by the body.
- Temperature effects of a "meal." The subject drinks lemon-flavored sugar water to measure the body's response.
- Bicycle exercise test. The subject exercises on three different occasions. During or after some of the tests, mild cooling is applied to the abdomen, front of the thigh, or hands.
- Measurement of exhaled air (indirect calorimetry). The subject wears a hood that collects and analyzes exhaled air for 15- to 30-minute periods.
- Photography and videotaping. The subject is photographed and videotaped. The images do not include views of any private parts, and the subject's identity is protected.
Animal models suggest that dissipation of body heat is an important physiological process that may affect energy expenditure, and thus may possibly modulate body weight. It is unknown, however, if deficient dissipation of heat can contribute to human obesity, or if obesity induces deficits in heat dissipation, and the relationship between obesity and heat in humans is largely unexplored.
We propose to study obese (BMI greater than or equal to 30 kg/m(2)) and normal weight (BMI less than or equal to 25 kg/m(2)) adults to determine possible obesity-related differences in: 1) regional body temperature heterogeneity (i.e., presence of localized areas of heat retention), 2) the extent to which locally retained heat may be co-localized with deep fat depots, 3) the effectiveness of specific body loci (e.g., the distal extremities) as dissipaters of heat, and 4) the ability of approaches that alter heat dissipation to modify deep-body temperature heterogeneity.
It is hoped that the results of this study will provide preliminary evidence for future studies that attempt to facilitate weight loss in obese subjects through effective, guided applications of heat management.
National Institutes of Health Clinical Center, 9000 Rockville Pike
National Institutes of Health Clinical Center (CC)
Results (where available)
- Source: http://clinicaltrials.gov/show/NCT00266500
- ClinicalTrials.gov processed this data on April 30, 2014
The purpose of this project is to establish a Center of Excellence in Research on Obesity that will focus on severe obesity. The prevalence of severe obesity (i.e., Class 2 and 3 obesity;...
The objective of this study is to test and evaluate the effectiveness of a parent-only treatment for childhood obesity. This study provides state-of-the-art treatment for childhood obesit...
The purpose of this study is to design and demonstrate the feasibility of implementing moderate and intensive environmental obesity prevention programs at major worksites.
The purpose of this study is to evaluate the efficacy of a culturally-appropriate childhood obesity intervention with Hispanic families. The program aims at preventing childhood obesity b...
The purpose of this study is to explore the pathogenesis and genetic susceptibility of obese subjects,providing a convincing argument for further treatment of obesity and metabolic syndrom...
Microalbuminuria was much more common among obese individuals indicating a probable association with obesity. However, association of microalbuminuria with interaction between obesity and central obes...
Chronic diseases such as obesity and diabetes are major causes of death and disability throughout the world. Many causes are known to trigger these chronic diseases, and infectious agents such as viru...
Obesity is a chronic disease of multiple etiologies. Alongside the traditionally recognized causes of obesity, such as genetic inheritance and behaviour/environmental factors, in recent years adenovi...
Obesity is a multifactorial, progressing and life-long illness that consists in an exaggerated collection of fatty tissue. In 1997 WHO acknowledged that overweight and obesity had the character of an ...
The number of obese older adults is on the rise, although we lack a proper definition of obesity in this age group. The ambiguity is primarily related to sarcopenia, the progressive loss of muscle and...
Medical and Biotech [MESH] Definitions
A condition of having excess fat in the abdomen. Abdominal obesity is typically defined as waist circumferences of 40 inches or more in men and 35 inches or more in women. Abdominal obesity raises the risk of developing disorders, such as diabetes, hypertension and METABOLIC SYNDROME X.
The condition of weighing two, three, or more times the ideal weight, so called because it is associated with many serious and life-threatening disorders. In the BODY MASS INDEX, morbid obesity is defined as having a BMI greater than 40.0 kg/m2.
Agents that increase energy expenditure and weight loss by neural and chemical regulation. Beta-adrenergic agents and serotoninergic drugs have been experimentally used in patients with non-insulin dependent diabetes mellitus (NIDDM) to treat obesity.
A status with BODY WEIGHT that is grossly above the acceptable or desirable weight, usually due to accumulation of excess FATS in the body. The standards may vary with age, sex, genetic or cultural background. In the BODY MASS INDEX, a BMI greater than 30.0 kg/m2 is considered obese, and a BMI greater than 40.0 kg/m2 is considered morbidly obese (MORBID OBESITY).
The discipline concerned with WEIGHT REDUCTION in patients with OBESITY.