SYDNEY, April 26 (Xinhua) -- While people that are overworked and under pressure often turn to high-calorie food to boost their spirits, a team of researchers from Australia on Friday warned that "comfort food" in times of stress can have an even bigger impact on weight gain than scientists had previously thought.
In a study conducted on mice, the Garvan Institute of Medical Research discovered that a high-calorie diet combined with stress resulted in more weight gain than the same diet in a stress-free environment.
According to the lead author of the study Dr Kenny Chi Kin Ip, this is because a molecular pathway in the brain which controls insulin called NPY, drives the additional weight gain in times of stress.
"Our study showed that when stressed over an extended period and high calorie food was available, mice became obese more quickly than those that consumed the same high fat food in a stress-free environment," he explained.
"We discovered that when we switched off the production of NPY in the amygdala (brain) weight gain was reduced."
"Without NPY, the weight gain on a high-fat diet with stress was the same as weight gain in the stress-free environment. This shows a clear link between stress, obesity and NPY."
In normal circumstances, the body produces insulin immediately after a meal, helping cells to absorb glucose in the blood and to send a "stop eating signal" to the brain.
But during times of chronic stress and in combination with a high-calorie diet, mice were found to have insulin levels 10 times higher compared to others that were placed in a stress-free environment.
The study showed that with these prolonged high levels of insulin, nerve cells quickly become desensitized, boosting their NPY levels which then promoted the urge to eat and reduced the ability of the mice to burn energy.
"Our findings revealed a vicious cycle, where chronic, high insulin levels driven by stress and a high-calorie diet promoted more and more eating," Head of the Eating Disorders laboratory at the Garvan Institute of Medical Research, Professor Herbert Herzog, said.
"This really reinforced the idea that while it's bad to eat junk food, eating high-calorie foods under stress is a double whammy that drives obesity."
