Ok, pet peeve rant coming. So strap yourselves in, kids.
Food is not a reward. Read it again. Food is not a reward. Not for chores, not for grades, not for behaving in difficult situations, and certainly not for complying with therapy.
Why Rewards Suck
There is a mountain of evidence that shows us that rewards do more harm than good. Alfie Kohn did an excellent job summarizing this issue 25 years ago, so I'm not going to belabor the point. But if you want details, buy the book.
In short, reward systems create children who grow up not understanding how to achieve internal validation. They develop no sense of satisfaction from achieving unless that achievement is rewarded. We are breaking our kids by rewarding and praising our kids to death. The other trick to rewards is that the effect extinguishes over time. A dollar for an A turns into $5 which turns into $20, and pretty soon you're shelling out $100 each report card.
Tainted Relationship
If rewards are bad, food rewards are evil. In addition to the problems with rewards, food rewards taint a child's relationship with food. Food is no longer a thing to be used to nourish our bodies. It becomes a commodity, to be bartered for with behavior.
I took care of a terribly abused child who broke the hearts of our nurses on the first night in the hospital by asking if he had earned his dinner that night. Imagine my horror years later when a child in my office asked his mom if he had earned his snack. But this child wasn't being abused, at least not in a conventional sense. He was in ABA therapy, and he responded very well to food rewards. So he had learned that he had to earn snacks.
If You Hadn't Heard...
If you're not aware (and I don't know how you could have missed it), there's an epidemic of obesity across the developed world. Children are becoming obese at such a high rate that previously adult diseases are now being seen routinely in kids. At the same time, 9% of Americans will have an eating disorder in their lifetime. Our relationship with food, as a society, is messed up. Food rewards, and the way they distort a child's relationship with food, are now a life-or-death issue.
If you're a parent, you need to stop offering food as a reward today, and you need to engage the adults in your child's life to do the same. Teachers and therapists can no longer entice children into compliance with food. There are better ways. And if we don't stop now, our kids will be the ones who pay for our mistakes.