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Why we (unconsciously) choose chocolate over an apple when were sad or stressed

You’re standing in your kitchen, feeling overworked and stressed. And hungry. Craving a snack, you contemplate your options. You can have one of the lovely looking Gala apples piled piously in your kitchen fruit bowl or some Ben & Jerry’s Chocolate Fudge Brownie ice cream, which is buried deep (but, alas, not forgotten) within your refrigerator’s freezer.

Which one do you choose? A new study explains why it’s likely to be the ice cream — and for reasons that have nothing to do with the ice cream conjuring up positive childhood memories or being more physically pleasurable to eat.

For, as this study published in the August issue of the Journal of Clinical Investigation discovered, even when we can’t see, taste or smell a so-called comfort food — when we’re totally unaware of what exactly we’ve eaten — the food still improves our mood.

The study’s methodology
For the study, researchers from the University of Leuven in Belgium recruited 12 healthy non-obese adults. An infusion of either fatty acids (most comfort foods are high in fat) or saline was delivered into their stomachs through a feeding tube. The researchers then induced sadness in the volunteers by exposing them to gloomy classical music and pictures of people with sad facial expressions. (Previous experiments have shown that such techniques can dampen people’s moods.)

The study’s volunteers filled out brief questionnaires throughout the experiment (which was repeated four times with each volunteer) in which they rated their sensations of fullness, hunger, nausea and mood. They were also hooked up to a functional magnetic resonance imaging (fMRI) machine, which scanned their brains to show changes in areas of the brain associated with sad emotions.

Both the subjective questionnaires and the objective fMRI brain scans found that when the volunteers were pretreated with the fatty acid solution, they were less saddened by the gloomy music and pictures than after they received the saline solution.

In fact, the fatty acid solution appeared to reduce the intensity of the volunteers’ sad emotions by almost half. As a commentary that accompanies the study points out, that reduction may be clinically meaningful, as it’s about the same as the effect of antidepressant medications on mood scores.

Interestingly, when the volunteers were presented with the sad music or pictures, they also reported feeling less full. The sad feelings, in other words, appeared to make them hungry.

“These findings increase our understanding of the interplay among emotions, hunger, food intake, and meal-induced sensations in health, which may have important implications for a wide range of disorders, including obesity, eating disorders, and depression,” the study’s authors concluded.

We are what we eat
I spoke about the study Tuesday with Giovanni Cizza, an endocrinologist at the National Institute of Diabetes and Digestive and Kidney Diseases (NDDKD) and a co-author of the commentary that accompanied the study.

Giovanni Cizza
niddk.nih.gov
Giovanni Cizza

“It provides an elegant explanation of something that we’ve known for a long time,” he said. That “something”  is, of course, that food and mood are intricately related. Many previous studies have found that we eat more when we’re sad, anxious or stressed.

But, again, the unique finding of this study is that comfort foods can affect our moods even when we’re unaware that we’re eating them. This suggests, said Cizza, that hormones involved in digestion are communicating directly with the brain.

And that may help explain why we find it so difficult to resist our cravings for fatty foods.

Of course, the study needs to be replicated before its findings can be considered definitive. “It had a small number of subjects,” Cizza pointed out, “and they were lean. We don’t really know what would happen if the subjects were obese.”

But the finding suggests, Cizza added, that the 19th-century German philosopher Ludwig Feuerbach was correct when he famously quipped, “We are what we eat.”

“If you can really modulate your mood through what you eat — if you can be less sad by ingesting fat — then in a way, we are what we eat,” said Cizza.

The study’s finding also has a take-home message for people struggling to maintain a healthy weight. “When people try to lose weight, they often feel guilty,” Cizza said. “Maybe this study can help them understand that it’s not only willpower.”

So next time you find yourself forgoing an apple for a bowlful of Chocolate Fudge Brownie ice cream, don’t feel so bad. You’re just responding to a strong and unconscious craving that’s deeply rooted in human biology.

Hmmm… That’s a stress-inducing thought. …. I wonder what’s in my kitchen.

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