PATH Breath measures your metabolic data through Breath once a month for 5 mins. The FAT Band then uses this metabolic data with 24 hour heart rate data collected from your wrist to predict your FAT and sugar burn through the day. Overtime, the app uses all this data to learn the minimum minutes of exercise you need to lose a pound a week.
KickStarter: https://www.kickstarter.com/projects/978573555/path-breath-fat-band-measures-fat-burn-from-your-b