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Do you eat when you’re stressed? This new study knows why

I have just been assigned this story on a very tight deadline.

My gut reaction: scramble for that giant bag of Smarties I vaguely remember stashing somewhere in my desk. It turns out I have an excuse for my mindless snacking even before I'd thought about lunch. I can blame my brain.

A new Canadian study has pinpointed how stress can temporarily rewire the nerve cells in the brain to ramp up hunger pangs. The findings finally put some science behind what people have thought for years.

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"There's lots of anecdotal evidence," noted Jaideep Bains, a scientist at the University of Calgary. "People say when they're stressed, they eat a lot … When you don't eat, you have this really increased desire to eat, that perhaps you don't sense the satiety signals the same way, or you tend to overeat."

And the findings could have implications for how we treat obesity, now a well-reported epidemic in wealthy Western societies, and the diet industry, a multibillion-dollar business, which has long been looking for the magic pill to control appetite.

Dr. Bains and a team of researchers from the university's Hotchkiss Brain Institute used rats to study how the brain reacts to stress. And in the case of rats, a key stress is availability of food. So the scientists took away the rodents' food supply for a day and then examined what happened in their brains.

They looked at the nerve cells, or neurons, of the hypothalamus, the ancient part of the brain, which has previously been identified as playing a key role in controlling appetite and metabolism. The hypothalamus is also the main area responsible for how the brain handles stress.

Their findings, published online this week in the journal Neuron, found that the endocannabinoids, or chemicals that are produced in the brain to control how cells communicate, which also regulate food consumption, were negatively impacted by stress.

When food was not available, the rats were flooded with a stress hormone, which in turn rewired the brain. These changes may damage how endocannabinoids regulate food intake and trigger the hunger drive.

"You just rearranged the wiring for your light switch," Dr. Bains said. "It turned out, what drove that entire switch was not a food-related signal, but was a stress signal."

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The connection is likely an evolutionary hangover from a time when sourcing food would have been a stressful event for humans and lack of food was a cue to find it, not ignore the signals from an empty belly.

But now, at least in First World countries, finding food isn't a problem. Overeating and binging on empty calories is. So are a multitude of modern-day stresses.

The research, which was funded by the Canadian Institutes of Health Research and Alberta Innovates – Health Solutions, examined rats, but it could have huge health implications for humans.

"It could be applicable to other types of stress as well," noted study co-author Quentin Pittman, "The stress that people suffer on a daily basis. We used a stress that was really relevant to a rat, but having a bad boss or having a high mortgage. ... Maybe those type of stressors in the human population would have the same kind of effects on important circuitry called the hypothalamus that are important in regulating our internal body health."

The researchers also found when they blocked the impact of the stress hormones in the brain, the lack of food didn't lead to rewiring of the brain. In effect, it cut off the heightened desire for food.

Dr. Bains pointed out that the diet industry did once unveil a product to target this interaction in the brain, but it didn't work. But, he said, it doesn't mean it's not possible.

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