A new, portable breathalyzer that pairs with a smartphone and Bluetooth can measure how well you're burning body fat and help you gauge the success of your diet and exercise program, according to a new report from Japan.
At this point, the device is only a prototype. It's pocket-sized, about 4 inches long, and weighs about 4.5 ounces. It operates on two AA batteries.
The device measures acetone, a metabolite produced from fat burning. When you burn fat, acetone levels rise in the blood, but are also exhaled. The new device is as reliable as a "gold standard" test (such as gas chromatography) to measure acetone, according to Satoshi Hiyama, senior research engineer at NTT Docomo, a Japanese mobile communications company.
"We found that the concentrations of breath acetone obtained from our prototype and from conventional gas chromatography have a strong correlation throughout our experiments," Hiyama said.
The researchers tested the device in 17 healthy men and women, reporting their findings online July 25 in the Journal of Breath Research.
"Enabling users to monitor the state of fat burning could play a pivotal role in daily diet management," Hiyama said in a journal news release.
To operate the device, the user blows into it and the acetone concentration levels are calculated and sent via Bluetooth or cable to an Android-based smartphone. It takes about 10 seconds.
For the study, after people blew into the breathalyzer, they also blew into a special collection bag that was measured with the conventional chromatography method.
Hiyama and his team had assigned the participants to one of three groups for the 14-day study. All were overweight by Japanese standards. (Body mass index thresholds in Asian populations are similar but not identical to U.S. standards, for example.)
One group carried on with their normal routine, with no instructions to exercise or restrict calories.
A second group was required to take part in jogging or fast walking from one half-hour to an hour a day. The third group did the same exercise routine but also was instructed to restrict calories.
Each day before breakfast, the men and women used a bath scale to weigh themselves and measure body fat, then used the breathalyzer.
Those in the first two groups did not lose substantial amounts of weight -- their breath acetone levels were constant. The researchers suggested that the exercise-only group members, allowed to set their own pace, weren't working hard enough.
Those in the third group who followed instructions lost substantial amounts of fat and their breath acetone levels rose.
The researchers speculate that the device might also be used in the prevention and treatment of diabetes. When diabetes is out of control, acetone breath levels rise.
Hiyama could not say what the device might cost or how soon it could be on the market.
"I think it's an interesting device," said Larry Birnbaum, a professor and chair of exercise physiology at the College of St. Scholastica, in Duluth, Minn., who reviewed the findings and has researched fat burning. He pointed out some limitations, including the small study size of 17 people.
One strength of the study, he said, is that the device results were compared with those of a "gold standard" test. "They did compare their device with gas chromatography and reported a strong correlation," he noted.
"That is good," Birnbaum explained. But he added that validity would be enhanced if independent researchers repeated that comparison. The device also needs to be tested on a larger number of people with varying levels of acetone in their blood and breath, he said.
In the future, Birnbaum said, if the device research bears out, it could provide people an additional piece of information. "It might help people stick with a diet; it might help them modify their diet."