A ‘vicious cycle’ with stress and diet
Researchers found the molecule NPY was the key to the weight gain. created naturally in both humans and mice as a response to stress, NPY stimulates consumption. once researchers turned off NPY production in mice, weight gain slowed down. In the absence of the molecule, weight gain on a high-fat, stress-filled diet was the same as weight gain on the same diet without stress. Researchers say this shows an obvious link between stress, obesity and NPY.
To find out what triggers the NPY increase throughout bouts of stress, the researchers analyzed the nerve cells that produce NPY, finding they have receptors forinsulin, one of the hormones that manages food intake. Normally, the body makes insulin when it receives a meal. That lets the body use glucose from the blood while signaling the brain to lower your appetite.
Stress raises blood insulin levels slightly. However combine stress with a high-calorie diet in mice, and insulin levels skyrocket to ten times higher than mice that are stress-free and on a standard diet.
“Our findings disclosed a positive feedback, where chronic, high insulin levels driven by stress and a high-calorie diet promoted a lot of consumption,” Herzog says. “This really strengthened the idea that even when it’s unhealthy to eat junk food, eating high-calorie foods under stress may be a double whammy that drives obesity.”
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