None listed
Conditions
Brief summary
Obesity is a major health issue worldwide. Despite global research efforts, effective treatments for obesity are limited. There are two kinds of fat in the body: white fat and brown fat. White fat functions mainly as an energy-storing organ and in excess results in obesity and complications such as diabetes and high blood pressure. Brown fat on the other hand releases the energy stored in fat as heat. It protects small animals and newborn human infants from cold temperatures. New imaging techniques have revealed brown fat to be present in significant amount in adult humans. Using special metabolic imaging, called PET scanning, brown fat is shown to be more abundant in lean individuals with lower blood glucose levels, suggesting that brown fat may regulate energy balance and metabolism. In animals, cold temperature and food both stimulate brown fat, resulting in release of energy. This is called adaptive thermogenesis, and it represents a considerable portion of total daily energy expenditure. Whether brown fat controls adaptive thermogenesis in humans is unclear. This is clinically relevant because if brown fat regulates adaptive thermogenesis in humans, strategies can be developed to stimulate brown fat to increase energy expenditure, which may be a new method to help attain weight control and develop treatment of obesity-related disorders. In order to determine the physiologic significance of brown fat activation, we designed a study investigating the effects of cold exposure and food on brown fat in humans. We hypothesize that adaptive thermogenesis in adult humans can be activated by cold or food, and the extent depends on individual brown fat abundance. Brown fat activity can be increased by cold stimulation, which could result in beneficial metabolic changes in the body. The aims of the current project are to: 1) determine relationship between brown fat and adaptive thermogenesis 2) investigate the underlying hormonal mechanisms and significance of brown fat activation Brown fat abundance will first be measured by PET scanning during mild cold condition. Volunteers then undergo metabolic and hormonal testing at standard ambient temperature (24 degrees). A parallel study will examine brown fat biopsies obtained during elective neck surgery to investigate mechanisms underlying brown fat activation. Significance: Based on its role in energy homeostasis and protection against obesity in animals, brown fat is likely to have a similar role in adult humans. Determining the contribution of brown fat to energy metabolism may lead to novel treatment strategies of obesity.
Interventions
This is an interventional study examining the relation between brown fat activity and glucose/energy homeostasis.
It involves two half-day studies (4 hours), 1 week apart, measuring brown fat quantity, energy burning rate and hormone levels. Volunteers will be exposed to i) mild cold (between 12 to 19 degree celcius - a personalised temperature in which volunteers feel cool but are no shivering) and also ii) be given 75 g of glucose as a drink to examine effect of cold and glucose on brown fat
This is an interventional study examining the relation between brown fat activity and glucose/energy homeostasis. It involves two half-day studies (4 hours), 1 week apart, measuring brown fat quantity, energy burning rate and hormone levels. Volunteers will be exposed to i) mild cold (between 12 to 19 degree celcius - a personalised temperature in which volunteers feel cool but are no shivering) and also ii) be given 75 g of glucose as a drink to examine effect of cold and glucose on brown fat activity.
Sponsors
Garvan Institute of Medical Research
Study design
Allocation
Non-randomised trial
Intervention model
Single group
Primary purpose
Diagnosis
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
Healthy volunteers
Exclusion criteria
Body mass index > 30 kg/m2. Significant cardiac, respiratory, thyroid, renal and/or hepatic dysfunction
Outcome results
None listed