Using a weighing scale to keep track of your weight is tricky. Your body can lose water, muscle or fat, but the scale simply picks up your overall weight. It doesn't reflect your gym obsession or fat loss with any accuracy. LEVL is a new portable device that analyses your breath to tell you if your body is in fat-burning mode. A white box holds a proprietary nano sensor that checks your breath for the level of acetone, a molecule that your body releases when it goes into fat burning mode, or ketosis. This isn't the first time we've seen tech like this: in 2013, NTT DoCoMo demonstrated something remarkably similar.