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Tracking How Much Food We Eat Can Be a Challenge

By Rita Rubin
WebMD Health News

Dec. 12, 2013 (Washington, DC) -- Anyone who’s ever belonged to a weight loss program knows the value of keeping a food diary -- a written record of every morsel or sip that enters the mouth. 

The problem is, what people say they eat isn’t often the whole truth. Sometimes they knowingly omit an embarrassing pig-out, like an entire sleeve of cookies or a whole carton of Rocky Road. Other times they simply underestimate a serving size.

Even inaccurate food diaries can help people lose weight -- although perhaps not as quickly as a careful record-keeper might -- but such journals can drive nutrition researchers crazy. The need for more accurate accounting of the what, when, and how much people eat has spurred the development of a variety of new gadgets. They include a microphone you wear around your neck that counts swallows, and the “HAPIfork,” which alerts dieters when they shovel food into their mouths too quickly.

“If you want to study nutrition, you have to know what people are eating,” Dale Schoeller, PhD, a professor of nutritional sciences at the University of Wisconsin, told an audience at the recent American Society for Nutrition meeting in Washington, DC.

In a perfect world, Schoeller says, scientists would be able to hook research subjects up to a GPS device to track their movement, monitor what they eat and how much,  listen to their digestive tract, and upload all the information to their computer. While that might work for dairy cattle -- Schoeller showed a slide of "well-connected" Holly the Holstein, whose owner was aiming to produce the most milk with the least food -- humans would likely rebel over being tracked that closely in their daily lives.

But scientists have been aware for decades that food diaries are fraught with problems, given that people don’t lose as much weight as their records indicate they should, he says.

The Good, the Bad and the Fattening

“People don’t always tell you the bad, or what they perceive as bad,” like that half-gallon of ice cream they ate after a tough day at work, Schoeller says. Plus, “the average patient figures a serving is what I put on my plate.” But plates have gotten bigger over the years, he says, from 12 inches to 14 inches wide, resulting in about a 40% larger surface area.

In the United States, the higher their body mass index (BMI), the more people underestimate how much they ate, he says. And for the most part, the longer people keep food diaries, he says, the more likely they are to trim the fat, so to speak, from their entries.

So what’s a scientist or a dieter supposed to do?

Schoeller has tried asking people to provide before-and-after photos of their plates, bowls, and glasses. After all, food photos are nearly as popular as selfies in social media these days.

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