While mom always warned that we are what we eat, most of us likely dismissed her nutritional advice and just asked her to pass the chips.

But a new psychology study seems to back her up and indicates long-term junk food habits can lead to obesity and cognitive impairments which are hard to reverse.

UCLA life scientists conducted a study using 32 female rats on two different diet regiments, one healthy (fish meal and ground corn) and one featuring highly-processed food heavy in sugar. In three months the 16 rats on the junk food diet were fatter and appeared more tired and sedentary than the 16 eating the healthier food.

"One diet led to obesity, the other didn't," said Aaron Blaisdell, a professor of psychology in the UCLA College of Letters and Science and a member of UCLA's Brain Research Institute. The research was funded by the National Science Foundation.

The news comes at a time when childhood obesity rates are under increasing scrutiny. As TechTimes reported in February new findings show that childhood obesity has plummeted by an astonishing 43 percent in the past decade, with data suggesting that attempts to educate parents and children on the benefits of nutrition and exercise are sticking. Today, as TechTimes reports, a new report indicates obesity is once again on the rise among children.

During the UCLA diet experiment the rats had to press a lever to receive a food or water reward. The junk food rats showed impaired performance and took longer breaks than the healthy food rats before returning to the task. During a 30-minute session the overweight rats took breaks that were nearly twice as long as the other group.

But what's most concerning, say the researchers, is that even after the diet regiment was switched up for six months, the heavier rats didn't lose much weight or show improved activity. The initial health food rat group didn't gain much weight or show slower responses after being on the junk food diet.

The researchers say the results reveal that a pattern of consuming junk food, not just an occasional binge, is responsible for obesity and cognitive impairments.

"There's no quick fix," said Blaisdell. "Our data suggest that diet-induced obesity is a cause, rather than an effect, of laziness. Either the highly processed diet causes fatigue or the diet causes obesity, which causes fatigue."

Blaisdell, 45, says his own personal diet is "what our human ancestors ate." He avoids processed food, bread, pasta, grains and food with added sugar. He says he's seen dramatic improvements in his health, both physically and mentally.

"I've noticed a big improvement in my cognition," he said. "I'm full of energy throughout the day, and my thoughts are clear and focused."

An expert in animal cognition, Blaisdell's research focuses on the relationship between health and lifestyle and the relationship between a junk food diet and cognitive impairments it may induce. His research will be published in this week's print edition of the journal Physiology and Behavior.

"We are living in an environment with sedentary lifestyles, poor-quality diet and highly processed foods that is very different from the one we are adapted to through human evolution," he said. "It is that difference that leads to many of the chronic diseases that we see today, such as obesity and diabetes."

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