Self-tracking devices like the
Fitbit do a fair, if imperfect, job at measuring how much you move and then
inferring how many calories you’ve burned in a day. But they don’t measure how
many calories you consume. You can enter calorie estimates into an app, but
doing so is a tedious and often inaccurate process.
GE researchers have a prototype device that
directly measures the calories in your food. So far it only works on blended
foods—the prototype requires a homogenous mixture to get an accurate reading.
But they’re developing a version of the device that will determine the calories
in a plate of food—say, a burrito, some chips, and guacamole—and send the information to your smartphone.
Matt Webster, the senior
scientist in diagnostic imaging and biomedical technologies
at GE Research who invented the
calorie counter, says eventually the device might be incorporated into a
microwave oven or some other kitchen appliance. Heat your food, and at the same
time get a readout of the precise calorie count, without measuring out portions
and consulting nutritional charts.
Webster analyzed nutritional
data from the U.S. Department of Agriculture—which contains detailed
information on thousands of foods—and determined that it’s possible to get an
accurate calorie estimate using just three pieces of data—fat content, water
content, and weight. The calories from all the other constituents of food—such
as sugar, fiber, and protein—can be approximated by subtracting the water and
fat weight from the total weight.
In tests using the prototype
to measure mixtures of oil, sugar, and water, results were within 5 to 10
percent of the results from standard, destructive means of measuring calorie
content, such as the bomb calorimeter that measures food calorie content by burning
it.
The device works by passing
low-energy microwaves through a weighed portion of food and measuring how the
microwaves are changed by the food—fat and water affect the microwaves in
characteristic ways. Getting a reading is easy using existing equipment if the
food is liquid or blended. Getting a good reading for a sandwich and chips will
require “virtual blending” Webster says. That could be done by developing
microwave antennas that form a more uniform distribution of microwaves than the
current equipment and using algorithms to get an average, or by progressively
scanning the food. In either case, the complete measurement could be taken in a
second or two.
Others are developing devices
that are being marketed as being able to count calories. For example, a pair of
devices have emerged recently on crowd-funding sites. But those devices are
limited to analyzing the surface of most foods (they work by measuring
reflected light). This approach might work to recognize a piece of food as an
apple, for example, whose caloric content can be looked up in a database. It
wouldn’t easily work with a burrito, where most of the calories are wrapped up
inside.
“We’re looking at waves that
pass all the way through the food. So you’re getting a complete measurement of
the entire food,” Webster says.
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