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Weight loss, one breath at a time: USDA lab tests ‘breathalyzer’ for calories to help dieters

GRAND FORKS — Leah Whigham imagines a future in which dieters could use a hand-held device to tell them right after a meal how many calories they just consumed, and all they’d have to do would be to breathe in the machine.

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She led a project this past year to develop such a device at the U.S. Department of Agriculture Human Nutrition Research Center in Grand Forks.

Having instant feedback could help people correct their eating habits quicker, she said. When people overeat, it doesn’t immediately show up on the scale, which can mistakenly lead them to believe they’re eating the appropriate number of calories, she said.

“Weighing yourself over time is a good measure, but the problem is that psychologically, we’re not connecting the eating with the increased weight in the future,” she said.

Whigham recently left for another job after developing and leading the project. But volunteers at the USDA lab continue to test the machine, which is now the size of a desktop computer. The research is, so far, the first of its kind.

Grand Forks has a special interest in obesity research. Local health care and social service agencies have identified obesity as a top health concern, and Altru Health System has set a goal of reducing adult obesity in Grand Forks County from 23 to 20 percent within four years.

The science

The USDA device works by examining the carbon in people’s breath, specifically Carbon-12 and Carbon-13, two isotopes, or variants, of carbon found everywhere in the environment.

Carbon might seem like an unusual choice to track weight loss, but according to her research, the ratio of each isotope in a person’s breath can actually help determine dietary information and nutritional status.

Carbon-12 is the most common, making up about 99 percent of the total amount of naturally occurring carbon in the atmosphere. Carbon-13 makes up the remaining 1 percent. Scientists can differentiate between the two because Carbon-13 has an additional neutron.

Fat stored in the body contains less Carbon-13 compared to proteins or carbohydrates in the body, according to Whigham. So, when a person eats fewer calories than he needs and his body begins to burn fat, the carbon dioxide he breathes out will contain less Carbon-13 in comparison to Carbon-12.

That’s how scientists can tell if someone is eating fewer calories and likewise, losing weight, Whigham said.

“When someone overeats, it jumps up within a few hours,” she said.

The idea for the study came to her in 2009 while she was working at the University of Wisconsin-Madison, where she completed a pilot study and wanted to do further research here. A colleague had already been using the breath test method and applying it to infection, so she combined that with her interest in finding ways for people to attain a healthy weight, she said.

The study

At the Grand Forks lab, Whigham led two studies. Volunteers here followed a highly controlled diet that catered to their own caloric needs. They were specifically asked not to exercise.

For the first nine days, the volunteers consumed 40 percent fewer calories than they needed to maintain their weight and on the 10th day consumed 40 percent more. The same volunteers came back and repeated the study, this time consuming 20 percent fewer calories for the first nine days.

Researchers chose 20 and 40 percent because that’s typically how much people need to reduce their caloric intake to lose weight. They also wanted to detect carbon ratio changes within a slight reduction of calories, said Whigham.

The volunteers then exhaled into plastic bags every hour (except at night). Each volunteer’s breath was compared to a sample of their own breath taken at the very beginning of the study.

Lab employees also manipulated the level of Carbon-13 in the diet by adding more sugarcane or corn, plants that naturally possess higher levels of the isotope, Whigham said.

“We needed to make sure if people’s breath was going up because they were eating more calories,” she said. “What if they’re not eating more calories, but they eat something with Carbon-13 in it, does that lead to a false test?”

The patent

USDA researchers hope the study will improve people’s eating habits and create awareness of how quickly food affects them.

Whigham, who now works for the Paso del Norte Institute for Healthy Living in El Paso, Texas, said the Grand Forks lab’s findings have just appeared in the International Journal of Obesity and they’ve just filed a patent.

“The next step is to use it on people who are eating their own choice of food to see if we can truly detect when someone overeats,” she said.

In the future, she’d like to see the creation of a portable device that would give instant results, similar to a diabetic’s glucose-monitoring machine, she said.

“The technology that’s available to us now could open us up to whole other fields of application,” she said.