BYU and Cornell found paying kids a nickel to eat vegetables beat forcing them onto trays

A December 2013 Slate post reports a Brigham Young University and Cornell study of US school lunches. Even when students were forced to put carrots or green beans on their plates, researchers found they threw away 70 percent of it, which the study estimated meant nearly $4 million of extra produce was binned each day.

The researchers ran a second study of small rewards in the lunchroom. The week-long experiments differed across 15 schools: some students could earn a nickel, others a quarter, and others a raffle ticket for a bigger prize. According to a quote from the paper in the Journal of Human Resources, rewards raised fruit and vegetable consumption by 80 percent and wasted food fell by 33 percent.

The authors say that, strange as it sounds, directly paying students to eat a fruit or vegetable is less expensive and gets better results than the alternative.

Mandated servings were mostly discarded.

Small immediate rewards are cheap relative to wasted food.

Tying the reward to eating avoids paying for food that is thrown away.

Reward the behavior you want, not the proxy: compulsion to take food produced waste, while paying for eating moved consumption.

Slate quotes the researchers that when the reward week ended, students returned to their earlier consumption, with no lasting improvement and no 'boomerang' of eating less than before.