Consider these two statements:
1. Humans are generally lazy.
2. If you measure something, and can see the results, it will improve.
Weight loss and gain are approximately determined by the simple laws of thermodynamics. If you put more energy into your body than you require, it will be stored as mass, and vice versa. Therefore, the simple equation of Calories in minus Calories out is a pretty easy way to determine if a person will gain or lose weight.
We’ve gotten pretty good at passively measuring caloric output. I’ve been wearing the BodyMedia Fit Link Armband, and plenty of others around the globe are monitoring with other “Quantified Self” devices such as the Jawbone Up, Nike+ Fuelband, various FitBits, and the Basis B1.
The thing we’re not good at is measuring caloric input. I’m good at it, but I’m not a normal person. When I’m cutting body fat, or performing an experiment that I’m determined to stick to, I track every macronutrient and Calorie that goes into my body with MyFitnessPal or DailyBurn. However, normal people aren’t that diligent (see rule #1), and they often don’t want to face the reality that the donut that they just ate may be half of the Calories that they require for the day. Ignorance is bliss, even if it’s self-imposed.
These “Calories out” measurement devices are proving that passive measurement tools work. If a person doesn’t have to perform work to measure their energy output, they’re perfectly willing to track and analyze it. In fact, it capitalizes on rule #2: If you measure something, and can see the results, it will improve. Dick Talens of Fitocracy recently wrote an awesome piece on generating a positive feedback loop for results, and I couldn’t agree more.
The thing that we haven’t gotten yet, is passive measurement and visualization of Calories in. The moment we can hook up some sort of combination glucose monitor + heart rate monitor + mass differential measurement tool to even ballpark the Calories we’ve ingested, there will be a gold rush to create weight-loss tracking tools with merely the effort of strapping on a device.
I don’t know where the state of scientific research is in this area, but the race is on. And if you’ve got any ideas of how to guess at how many Calories a person has ingested, I’d love to work with you.