Human Whole Room Calorimeter
A whole room calorimeter (WRC) allows energy expenditure to be calculated based on measurements of air samples (indirect calorimetry). The person being studied remains in a closed room with a constant and measured supply of fresh air. Gas analysers attached to the unit measure oxygen consumed and carbon dioxide produced. The balance of oxygen consumed and carbon dioxide produced varies according to activity and the utilisation of different fuels by the body (carbohydrate, protein and fat). In this way, the WRC not only measures a person's energy expenditure, it also evaluates their ability to burn different fuels.
What are its advantages?
The ability to assess the relative amounts of carbohydrate and fat utilised as fuel is the major advantage of the WRC. This is done by assessing the respiratory quotient (RQ = CO2:O2), bearing in mind that the RQ of carbohydrate is 1:00 and of fat is 0.7. Thus, the higher the RQ, the more carbohydrate is used as fuel and the lower the RQ, the more fat is being oxidised. This simple principle lies at the core of a great deal of research in human metabolism. Knowledge from research in this area will be useful in many areas and in particular may help us to understand some of the problems in the management of obesity and related disorders. Some of the questions still to be pursued include:
- What are the factors that influence a person's ability to burn fat?
- What role does exercise and physical activity play?
- Does the type of fat make a difference?
- Can novel food ingredients and products demonstrate differences in fuel utilisation compared to other foods?
What does the WRC look like?
The University of Wollongong has built a dual calorimeter. That is, two small rooms with a window in between, located in building 41 and overlooking tree tops to the Pacific Ocean in the distance. The rooms look like small bed-sitters, equipped with basic facilities such as desk, chair, bed, telephone, television, computer, sink and toilet. They have separate, airlocked two-way cupboards for passing food, urine samples and blood samples respectively. The design is based on a well-established model at the University of Maastricht in the Netherlands.
How is the Research conducted?
The people being studied spend 24 to 72 hours in the rooms and follow the study protocol reading, sleeping, sitting or riding the exercise bike. They can communicate between rooms, use the Internet and make phone calls. Although free to leave (the doors are not locked), experience has shown that most people enjoy their quiet stay. Children can also be studied with this facility.
Why do we need research in this area?
Energy balance and use of fuel lie at the centre of two major public health concerns in much of the world today: obesity and type 2 diabetes mellitus. The problem has been well established by health authorities that are now issuing warnings of global epidemics. While the message is simple, eat less and exercise more, the solutions are complex. We need to understand more about how the body uses fuel in a range of environmental contexts, including the changing food supply. Clinical and population interventions need to be more targeted and effective, and there are opportunities for food manufacturers to develop functional foods to target energy balance. All of these actions need a strong research base and calorimetry can provide invaluable information to address the key questions.
How will the Research findings be applied?
Like all areas of science, new information generated from this research will make a contribution to a much larger picture. For example, in assessing the effects of dietary approaches, early research may have been done in laboratory settings, but the theories derived must be shown to work in humans. Research with the WRC will be able to demonstrate effects at the whole body level, which in turn provide information for more expensive clinical trials involving a greater number of people. In this way, the domains of science are usefully and economically linked in establishing evidence for practice and for product development. The WRC has a very important and unique position in this process.
Where do I go for more information?
If you are interested in participating in a clinical trial, please visit our recruitment page for details on our current activities. To speak with one of the clinical trials team, call us on 02 4221 3466.
If you are interested in partnering with the Smart Foods Centre to conduct a clinical trial, please contact Linda Tapsell on 02 4221 3152.