NTT DOCOMO

Tired of stepping on the scale to get a vague idea of whether all the hard work you put in at the gym is paying off? A new device developed in Japan could help people better gauge which activities are actually burning fat.

At 10 centimeters in length and weighing 4.4 ounces, the portable device measures acetone levels from the user's exhale. (Elevated levels generally indicate that the body has begun to break down fat.) It then sends the results to a smartphone via Bluetooth or a cable within 10 seconds.

Acetone is expelled through tiny sacs called alveoli when we exhale, though it is also produced when fat is broken down. This means that breath acetone levels can also help diagnose and monitor diabetes, which the researchers are looking into as well.

But a new study testing the device, which was published July 25 in the Journal of Breath Research, revealed something interesting when it comes to burning fat. When researchers at the NTT DOCOMO Research Laboratories in Japan tested it on 17 healthy adult volunteers (11 men, six women), they split the volunteers into three groups: one to make no change in diet or exercise, another to take part in light exercise 30 to 60 minutes a day, and another to take part in the same exercise routine but also restrict caloric intake.

Every day after breakfast for two weeks, all volunteers measured their body weight, body fat percentage, and breath acetone concentrations via the device. Lo and behold, the first two groups weren't burning fat, and their breath acetone concentrations held steady. But the third group of volunteers, who combined exercise with caloric restrictions, not only lost fat, but their breath acetone concentrations increased significantly, suggesting that the device was doing its job and that people who want to lose fat shouldn't rely on light exercise alone.

"Because obesity increases the risk of lifestyle-related illnesses, enabling users to monitor the state of fat burning could play a pivotal role in daily diet management," said principal investigator Satoshi Hiyama in a news release. "Current standard methods, however, are still not practically suitable for point-of-care instrumentation for diet-conscious people who wish to monitor their own fat metabolism at home or outside."

While the device could be a serious buzz kill for anyone in love with an exercise routine that isn't working, or that is combined with a highly caloric diet, it could also provide a far more meaningful picture of what is and isn't working for those who want to burn fat.