Note: This is an article I wrote that was originally published on TransformingScience.com.
The one-of-a-kind Human Whole-Room Calorimeter at the UNC Chapel Hill Nutrition Research Institute can be used for a wide variety of research studies. Read on to learn about how this technology works, how experts at the Appalachian State University Human Performance Laboratory are studying metabolism, how these studies are vital for improving human health, and what a typical day as a study participant is like (including getting paid).
What they call the Human Whole-Room Calorimeter or Metabolic Chamber is essentially a small room that can calculate how much energy (calories) a person expends (both while resting or moving). This is balanced with the energy taken in through the diet over a 24-hour period. By controlling what you do and what you eat while in the chamber, researchers can accurately measure how much energy it takes to do certain things.
The metabolic chamber at the Nutrition Research Institute (NRI) is equipped with a bed, toilet, and sink. It also has the space to accommodate a treadmill or a stationary bike depending on the requirements of the study being conducted. Research staff can send food and other items through an airlocked compartment, and there are also ports for blood draws if a certain study requires them. There is also a television and – of course – WiFi.
The metabolic chamber is unique; there are only about 26 other similar rooms in the country, and it’s the only one in the Carolinas. This type of technology is essential for researchers who want to study energy balance and fuel use.
The first chamber study was conducted in 2011. The NRI and teamed up with the Appalachian State University (ASU) Human Performance Laboratory, recruiting 10 male participants to test the effect of 45 minutes of vigorous cycling on post-exercise RMR as measured in the metabolic chamber and contrasted with a rest day to determine how much and how long that exercise affected post-exercise energy expenditure. They found that 45 minutes of vigorous exercise resulted in 519 more calories burned compared to the rest day, and post-exercise calorie-burning was significantly elevated for 14 hours, resulting in an additional 190 calories expended, again compared to the rest day.
PARTICIPATING IN A CHAMBER STUDY
Orientation and baseline testing is the first step of any chamber study. Before your first day in the metabolic chamber, you’ll have a DEXA (Dual-Energy X-ray Absorptiometry) scan done at the NRI as part of your orientation and baseline testing. This machine provides precise measurements of total and regional body composition through high-resolution imaging. However, it is noninvasive and includes very low radiation exposure. Plus, you’ll be able to have a copy of your DEXA results, which include measurements like percent body fat, resting metabolic rate, and bone mineral density.
On your day in the chamber, you’ll arrive at the NRI in the morning between 7:00 and 7:30 to change into (very comfortable) scrubs and take any necessary measurements before entering the chamber around 8:00. Once you’re in the chamber, you can essentially do whatever you want (read, watch TV, use your laptop) as long as you are seated and remain as still as possible. There will always be a monitor on duty if you need anything. Every hour, the monitor will remind you to stand up, stretch, and walk for about two minutes. They will also give you a sheet of paper to take notes about your activity so you can replicate it to the best of your ability on your second visit. To exit the chamber, all you have to do is turn a big red button, and there’s an arrow pointing to it on the wall. Plus, there’s a window inside the chamber that faces the outdoors. No need to get claustrophobic!
The monitors serve you breakfast, lunch, and dinner, with a snack in between lunch and dinner. Don’t worry at all about getting hungry – the meals provided are tasty and filling. Plus, thanks to the metabolic chamber providing live data, the staff know your calorie needs at all times.
If it’s your exercise day, you’ll run on the treadmill around mid-morning. You rest for 45 minutes after the exercise, then you use sanitary wipes to feel clean again, and you can change into clean scrubs. If the study requires you to take supplements or provide blood samples, the monitors will tell you what to do. In the chamber, there are two intercoms that you can use to communicate with the monitor, one near the treadmill and one near the bed. There’s also a window where you can see the monitor, and a webcam so they can see you. Don’t forget – the toilet is not within view of the webcam and there is a curtain over the window. Your privacy is respected while you are in the chamber! The lights go out for “bedtime” at 10:00, and you sleep (or stay as still as possible when you’re awake) until 6:45 or so. You will be compensated well for your time, even if you complete just one visit.
In studies investigating exercise and energy expenditure, the second day is essentially the same as the first but with one key difference: on this visit you will spend 45 minutes on a treadmill, exerting yourself to 75 percent of your “V02 max,” the maximum amount of oxygen that you use during intense exercise (measured as milliliters of oxygen used in one minute per kilogram of body weight). Before you begin the study, they will test your V02 max by having you run on a treadmill at an incline. In the chamber on your exercise day, it’s a tough workout. But you can do it!
Metabolism studies are important because there is an obesity epidemic in the United States, caused by excessive calorie intake and a lack of physical activity: 69 percent of adults are overweight, with a BMI of 25 or higher, and 35 percent of adults are obese, with a BMI of 30 and higher. Obesity increases the risk of a variety of conditions that are linked to heart disease, including high blood pressure, diabetes, and high cholesterol. Heart disease is the leading cause of death for men and women worldwide.
So by studying the human metabolism, researchers from ASU and the NRI also want to help people effectively and safely lose weight to reach a healthy weight, lowering their risk of heart disease and other complications. Here a few simple recommendations:
- Eat more carbohydrates and dietary fiber from whole grains
- Eat more fruits and vegetables
- Eat less fat to reduce overall caloric intake
- Engage in physical activity most days of the week, with a total of 150-300 minutes per week
ASU and NRI experts have found that limiting calorie intake – eating less – has the biggest impact on weight loss. Exercise helps, but it must be more than 60 minutes per day to be meaningful. In other words, physical activity is more important for improving health (a good thing!) than for accelerating weight loss.