To stick to that New Year's resolution to lose weight, you know you have to consume fewer calories than you burn.
But just how many calories is that? It's a question that vexes many dieters because the answer can vary widely among people.
If you don't know your metabolism rate, you might cut too many calories and get so hungry you give up dieting.
Or you might overestimate how much you can eat on a weight-loss plan and wonder weeks later why you're not losing.
But accurately determining your metabolism rate is easy now, thanks to new gadgets that a small but growing number of health-related businesses are using in northern Nevada.
Or if only pen and paper are handy, you can estimate calorie burn, using a nationally recognized formula developed at the University of Nevada School of Medicine in Reno.
The American Dietetic Association recently recommended that formula as the most accurate for estimating metabolic rates.
The newest high-tech tools for measuring metabolism are called the MedGem and BodyGem, developed by HealtheTech Inc.
in Golden, Colo., and introduced commercially in 2000.
These hand-held portable devices, each about the size of a cell phone, can measure resting metabolic rates in less than 10 minutes.
The resting metabolic rate is the number of calories a body needs to function at rest - about 60 percent to 70 percent of a daily total including physical activities.
A person's activity level is then factored into an equation to figure the total number of calories needed daily.
The MedGem is marketed primarily to hospitals, and the BodyGem is marketed to allied health professionals, such as fitness trainers and nutrition counselors.
Although the MedGem provides more sophisticated data for doctors to use, both devices provide accurate readings, says Vicki Bovee, a registered dietitian and clinical projects administrator at the Center for Nutrition and Metabolic Disorders at the University of Nevada School of Medicine in Reno.
Before it switched to the MedGem, the center at UNR measured metabolic rates with a 500-pound piece of cumbersome equipment that was difficult to use.
With the MedGem or BodyGem, a person simply holds the device and breathes into an attached mouthpiece for several minutes.
Sensors measure oxygen consumption, ventilation, temperature, humidity and barometric pressure, and then provide a digital reading.
Herbal Rose Metabolic Center in Reno began offering metabolic testing with the BodyGem a year ago.
President Jim Jenks says response has been excellent, and many people are surprised by the test results.
One friend thought he was eating lightly until he learned his metabolism was much slower than he thought.
Other clients have been surprised to find that their metabolic rates are faster than they believed.
Herbal Rose now offers an assessment for $35 that includes body-fat percentage and metabolic rate testing and recommended calorie levels for maintaining or losing weight.
The whole process takes 30 minutes.
Jenks says he also offers the testing at company sites for employee wellness programs.
UNR's Center for Nutrition and Metabolic Disorders offers an assessment by a registered dietitian for $80 that includes measurement of calorie burn rate, body fat percentage, height and weight, body mass index, waist circumference, blood pressure and pulse and health risk related to those results.
Other northern Nevada businesses that offer the metabolic testing using the BodyGem or MedGem can be found on HealtheTech's Web site.
Meanwhile, a variety of formulas have been developed to estimate metabolic rates, the most widely used, the Harris-Benedict, dating back to 1919.
But in October, the American Dietetic Association, after comparing various formulas, recommended the Mifflin-St.
Jeor as the most accurate for estimating metabolic rates.
Sachiko St.
Jeor, chief of UNR's Division of Medical Nutrition, and other researchers developed the formula from data collected in the 1991 Reno Diet Heart Study.
St.
Jeor also happens to be on the scientific advisory board for HealtheTech, developer of the BodyGem and MedGem.
(You can find the formula online on a host of Web sites by doing a search for Mifflin-St.
Jeor.) St.
Jeor says health professionals have been using the locally developed formula for the last 10 years, but the recommendation by the American Dietetic Association will likely increase its use.
