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http://www.livescience.com/5635-high-fat-diet-stupid-lazy.html

"By now, we've all heard that high-fat diets are bad for our health in the long run. But what about the short-term?

A new study on rats finds that 10 days of eating a high-fat diet caused short-term memory loss and made exercise difficult. While the finding may not seem a big surprise, the researcher say it might suggest that high-fat diets make humans lazy and stupid.

"Western diets are typically high in fat and are associated with long-term complications, such as obesity, diabetes, and heart failure, yet the short-term consequences of such diets have been given relatively little attention," said Andrew Murray, co-author of the study and currently at the University of Cambridge in the United Kingdom. "We hope that the findings of our study will help people to think seriously about reducing the fat content of their daily food intake to the immediate benefit of their general health, well-being, and alertness."

The findings are detailed in the FASEB Journal.

Rodents are thought to be good analogues to humans for studies like this, but research in humans would be needed to confirm that the effects cross over. Also, because rats live much shorter lives, study effects may play out on significantly shorter time scales than in humans.

Murray and colleagues studied rats fed a low-fat diet (7.5 percent of calories as fat) and rats fed a high-fat diet (55 percent of calories as fat). Muscles of rats eating the high-fat diet for four days were less able to use oxygen to make the energy needed to exercise, causing their hearts to worker harder — and increase in size.

After nine days on a high-fat diet, the rats took longer to complete a maze and made more mistakes in the process than their low-fat-diet counterparts.

In the fat-laden rats the researchers found increased levels of a protein called uncoupling protein 3, which made them less efficient at using oxygen needed to make the energy required for running.

"It's nothing short of a high-fat hangover," said Dr. Gerald Weissmann, editor-in-chief of journal. "A long weekend spent eating hotdogs, French fries, and pizza in Orlando might be a great treat for our taste buds, but they might send our muscles and brains out to lunch."