At first glance, the Lumen looks a bit similar to a breathalyzer \u2014 at the top, there\u2019s a mouth-piece to breathe into in order to populate results. Every morning, you\u2019ll take a breath into the device and the companion app will you show you information like your daily goal for carb consumption, along with meal and snack recommendations.\r\nTo help keep you on track, the Lumen app comes with a \u201cfood search\u201d feature that allows you to look up certain foods to find out how many carbs each contains. For additional help, the app allows you to submit photos of your meals to nutritionists for feedback in order to get an expert opinion.\r\nBut how does it work, exactly? The Lumen uses Respiratory Exchange Ratio, which is the preferred method for determining metabolic fuel. By taking a single breath, the Lumen measures the carbon dioxide production and oxygen uptake of a user\u2019s breath in order to calculate how much energy is being burned from carbohydrates or fat.\r\n\t\r\n\t \r\nFrom there, the Lumen curates a personalized plan for you to follow without having to constantly log your food intake or activity each day. Using artificial intelligence that adapts to your nutritional patterns and behavior, the device is meant to teach you about your body \u2014 specifically carbohydrate to fat ratio insight and when it\u2019s best to use an energy source to receive maximum results.