Kelly Morrow, MS, RD, CD, a clinical supervisor at Bastyr Center for Natural Health, says people trying to manage their weight sometimes overestimate how much they need to cut back.
"When people are overweight, they often restrict their caloric intake too much when dieting," Morrow says. "That limits their success. They often feel tired and hungry. It puts stress on the body and they could end up losing excess muscle along with the fat."
The key is determining your exact metabolism — the rate at which a body turns nutrients into fuel. That's become easier through the indirect calorimeter, a device that measures a patient's exchange of oxygen and carbon dioxide to gauge their energy consumption.
Bastyr Center recently acquired a calorimeter and has found it useful for patients who want to either lose or gain weight, according to Morrow, who is also a core faculty member in the Bastyr University Department of Nutrition and Exercise Science.
In the past, nutritionists advising patients on weight management relied on estimates to determine metabolism. Their equations, based on factors such as age, height and body weight, are useful for some patients. But they're often inaccurate, especially for people with hormonal imbalances and thyroid issues, people with major illnesses such as cancer, or people who are severely over- or underweight, reports Morrow.
"The predictive equations can be quite wrong," she says. "They use information gathered from lots of people, but there is still a margin of error. The calorimeter is useful for anybody who wants to know exactly how many calories they're burning."
Personal trainers, dietitians and other health and fitness professionals have all found uses for the calorimeter, which is frequently referred to by its brand name, MedGem.
The device has also proved valuable for athletes and others wanting to gain weight. It showed Morrow that one lean 14-year-old who stands 6 feet 2 inches tall was burning 2,800 calories a day at rest. She advised him to eat about 4,000 calories a day to keep up with athletic training and reach his weight-gain goals.
"It's good that we did a calorie assessment, because we could see the numbers much more clearly," says Morrow.
Patients using the calorimeter breathe into a small mouthpiece (like a snorkel) for 10 minutes while lying still. They're instructed to abstain from food, caffeine and tobacco for four hours before the measurement.
To learn your specific calorie needs and gain tools for healthy weight management, make an appointment with a Bastyr Center nutrition team by calling (206) 834-4100.