The challenge of tracking what people eat

By Rita Rubin
WebMD Health News

12 December, 2013, Washington, DC)--anyone who has ever been in a weight loss program know the value of keeping a food diary--a written document with each mouthful or sip that enters the mouth.

The problem is, what people say they eat are often not the whole truth. Sometimes they deliberately omit an embarrassing pig-out, a whole sleeve of cookies or a whole carton of Rocky Road. Other times they underestimate simply a portion.

Even bad food diaries can help people lose weight--but perhaps not as fast as a careful record-keeper can--but such magazines may operate nutrition scientists crazy. The need for more reliable record of what, when and how much people eat have spurred the development of a variety of new gadgets. They include a microphone that you wear around your neck that is swallows, and "HAPIfork," which warns dieters as they shovel food into his mouth too quickly.

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

In a perfect world, Schoeller said, scientists could link subjects up to a GPS device to track their movements, monitor what they eat and how much, listen to their digestive tract and upload all the information into his computer. While that might work for dairy cattle--Schoeller showed a picture of "well-connected" Holly in Holstein, whose owner is designed to produce the most milk with a minimum of food--people would likely rebel that tracked closely in their daily lives.

But researchers have been aware for decades that food diaries are fraught with problems, given that people don't lose so much weight that their records indicate they should, "he said.

"People don't always tell the bad, or what they perceive to be poor," like that half-gallon of ice cream they ate after a tough day at work, Schoeller said. Plus, "average patient numbers a portion is what I put on my plate." But tiles have become bigger over the years, he says, from 12 inches to 14 inches wide, resulting in a 40% greater surface area.

In the United States, the higher the body mass index (BMI), the more people are underestimating how much they ate, "he said. 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 posts.

So what is a scientist or a dieter to do?

Schoeller has tried asking people to provide before and after photos of their dinner plates, bowls and glasses. Food photos are almost as popular as selfies in social media these days.