Joe Price, an economics professor at Brigham Young University, and David Just of Cornell University, said previous research suggests a federal rule that prompted the nation's schools to serve an extra $5.4 million worth of fruits and vegetables each day, results in students throwing out $3.8 million of that produce in the garbage each day.
However, the researchers said paying students directly to eat a fruit or vegetable is less expensive and gets better results.
Just and Price conducted a study to measure the effect of small rewards in the lunchroom. The week-long experiments in the 15 different schools offered students earn a nickel for eating a serving of fruit or vegetable, others a quarter, and others a raffle ticket for a larger prize.
The study, published in The Journal of Human Resources, found offering small rewards increased fruit and vegetable consumption by 80 percent, while the amount of wasted food declined by 33 percent.
Some fear prizes will prevent children from developing their own motivation to eat things that are good for them, while others fear the boomerang effect -- children eating less fruit and vegetables when the rewards disappeared, the researchers explained.
Price and Just measured fruit and vegetable consumption before and after the week-long experiments. When the week of prizes ended, students went back to the same level of fruit and vegetable consumption as before -- no lasting improvement, but no boomerang effect either, the study said.
The researchers are studying whether extending the experiments over three to five weeks might yield lasting change.