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A diet of junk food inevitably leads to poor health, but new research has found that stress can have the same effect.

PROVO — A diet of junk food inevitably leads to poor health, but new research has found that stress can have the same effect.

"We all know that stress can be harmful in a lot of ways," said Laura Bridgewater, professor of microbiology at Brigham Young University and associate dean of BYU's College of Life Sciences.

Stress has been tied to a number of unhealthy conditions, Bridgewater said, including obesity, Type 2 diabetes, heart disease and depression.

And some of those tend to be more common in women.

"In society, women tend to have higher rates of depression and anxiety," Bridgewater said. "This study has made me wonder if it has to do with differences in the gut microbiota."

Her research — involving male and female mice with regular and high-fat diets that were put into stressful situations — revealed that when the female mice were exposed to stress, the microorganisms responsible for digestion and metabolic health were disrupted, similar to if they had been eating a high-fat diet.

The study, published in Nature's Scientific Reports, suggests that the body's response to stress is powerfully shaped by diet. Both stress and a high-fat diet can alter gut bacteria and contribute to obesity.

Bridgewater's research, done in collaboration with China's Shanghai Jiao Tong University, aims to further examine a perceived correlation between obesity, stress, gut bacteria and mood disorders. The results point to "distinct gender differences in the impacts of obesity and stress on anxiety-like behaviors, activity levels and composition of the gut microbiota."

The mice were fed their respective diets and then subjected to mild stress, such as damp bedding, being forced to swim in hot or cold water, being tilted in their cages without bedding, light during the night and dark during the day, and predator smells and sounds, among others. Scientists tested fecal pellets before and after the tests to see how the mice were affected, also measuring anxiety based on how much and where the mice traveled in a designated space.

Male mice on the high-fat diet exhibited more anxiety than females on the high-fat diet, also showing decreased activity in response to stress. But it was only in the female mice that stress caused a change in the gut similar to what would happen on a high-fat diet.

In short, stress, like a high-fat diet, can alter the bacterial makeup of the intestines and lead to changes in physical health.

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Stress, the study gathers from previous academic research, can also trigger mood disorders — such as anxiety and depression — and promote obesity.

Bridgewater said that even though the results were found in mice, the message can apply to humans, too.

"Stress can hurt us, and it can have physical changes," she said. "It can change our gut bacteria in a way that is as if we were eating a very unhealthy diet. So stress needs to be one of those things we think about when we're trying to keep ourselves healthy."