One of the most basic questions in nutrition research is also one of the hardest to answer: How much do people eat?
For the past year, researchers at the Beltsville Human Nutrition Research Center have been looking for the answer in a study that involves a half-dozen scientists and more than 500 subjects.
It is a multifaceted investigation that includes interviewing subjects about the foods they recall eating, measuring their height, weight and body fat, outfitting them with a monitor on a belt that measures their activity and investigating how long it takes their bodies to pass specially marked molecules contained in a small cup of water.
As experiments go, this one isn't especially onerous for the participants. They eat their usual foods and continue with their usual activities. They get $325 if they finish the study. They do, however, have to collect urine samples every day for two weeks.
The study is a first for Jan Lobatz, a 61-year-old nurse-midwife from Bethesda. Although she works in medicine, she has never been part of a scientific study.
She heard about the study from a friend who participated and thought it sounded interested.
On her first day of the study, she spent several hours at the center answering questions about the food she eats, and undergoing a variety of medical tests, including a full-body scan that measured bone density and body fat.
"It's interesting to be on the other end of the pole," she said.