Buying a fitness tracker is easy compared to figuring out how to find an accurate caloric content of your food, but that didn't stop General Electric(s ge) Researcher Matt Webster from trying to make his wife happy. When he asked if she wanted a Fitbit, she said having something that counted calories would be more useful. So he bought her a Fitbit.

But then he also went to his lab at GE and started tinkering with a calorie counting device. So far he's built a prototype that measures the water, water and volume of food,. The current version is accurate within 5 percent to 10 percent of calories, but is a metal box you approach with safety goggles on, judging by the short video GE published.

The GE device may never make it to market, but the idea of building devices or imaging algorithms that can tell what people are eating is one that's getting a lot of research attention. Thanks to fitness trackers, connected scales, blood pressure and heart monitors and even connected mattress pads, we know a lot about what's happening in our bodies and our energy outputs, but inputs are still a mystery. If GE's product ever makes it to market it will compete with ideas such as SRI's photo-analysis of foods, TellSpec's laser spectrometer and Consumer Physics' handheld connected laser spectrometer.

Disclosure: Fitbit is backed by True Ventures, a venture capital firm that is an investor in the parent company of Gigaom.