Any parent who ever appeased cranky kids with Happy Meals ­– and every doleful soul who smothered woes with comforting mac-and-cheese – knows intuitively that mood and food do more than rhyme.

So, leave it to an international team of scientific researchers, including one in Cornell’s Food and Brand Lab, to question: Why, when someone is in a bad mood, will they choose to eat junk food? And why, when someone is in a good mood, will they make healthier food choices?

“People use food to either maintain a good mood or regain a good mood, and if you’re already in a good mood you tend to eat more healthfully than if you’re in a bad mood “ says Brian Wansink, a professor in Cornell’s Dyson School of Applied Economics and Management and a co-author of the paper, “Better Moods for Better Eating?: How Mood Influences Food Choice,” published online Jan. 25 in the Journal of Consumer Psychology.

“The take away of this study is you can change mood and eat better. Before a snack or meal, think of something that makes you happy or grateful, and you’ll eat less and better,” adds Wansink, the Food and Brand Lab director and a perennial foe of “mindless eating.”

Says co-author Meryl P. Gardner, associate professor of marketing at the University of Delaware’s Lerner College: “Understanding why we make bad food choices in bad moods can help us make better choices. When we think about the future, it's almost as if we are physically taking a step back, enabling us to see our more fundamental values – like health and nutrition. We can use that to make wiser choices rather than letting our moods dictate our behavior.”

Nearly 800 experimental subjects frowned and smiled, yearned and grumbled through the mood/food studies, beginning with 211 PTA parents testing the effect of a positive mood on evaluations of indulgent and healthy foods.

Then, like potato chip eaters who can’t stop at one, the researchers just had to have three more studies, including: Do undergraduate students in a negative mood crave indulgent foods, and do students in a positive mindset desire to remain healthy into old age?

Next, can experimenters alter participants’ focus on the present versus the future – along with their mood – and measure how much healthy and indulgent food undergrads consume? (One test pitted fresh grapes against M&M’s – with surprisingly encouraging results for dieters of all ages.)

Lastly, a study involving 110 university students focused specifically on thoughts related to food choice and what researchers called “differentiated concrete taste versus nutrition benefits.”

Gardner, Wansink and their South Korean colleagues, Junyong Kim of Hanyang University and Se-Bum Park of Yonsei University, say they succeeded in demonstrating “that when people are in a good mood, things seem OK, and they can take a big-picture perspective. This kind of thinking allows people to focus on the more abstract aspects of food, including how healthy it is.”

But even a well-designed, comprehensive study like theirs can’t solve all the world’s mysteries, the scientists concede, calling for further research. “Such research might provide insight,” they write, “into what happens when restrained eaters fall off the wagon or when people try to eat just one potato chip.”