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Key enzyme tunes fat metabolism

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Why do some people stay lean no matter how they eat? It hardly seems fair.

If you’ve always suspected that some people have a biological advantage staying lean, new evidence shows you may be right. Researchers led by Hei Sook Sul, professor of nutritional sciences and toxicology, recently identified an enzyme that plays a much more important role than presumed in controlling the breakdown of fat.

“We have discovered a new enzyme within fat cells that is a key regulator of fat metabolism and body weight, making it a promising target in the search for a treatment for human obesity,” said Sul, the principal investigator of the research.

Sul’s study compared mice without the gene for expressing this enzyme with a control group of normal mice. Researchers offered the two groups of mice an all-you-can-eat buffet of tasty, high-fat foods. Notably, the enzyme did not appear to affect appetite, as the two groups ate equivalent amounts of food. However, as the mice aged, the disparity in weight gain became clear. The researchers noted that the missing enzyme did not change the number of fat cells, but simply kept the cells from accumulating excess fat.

Before this study, the assumption had been that endocrine factors—hormones that travel through the bloodstream to fat tissue—were the key players in controlling fat metabolism and body weight. The new findings show that much of the action is occurring within fat tissue itself.

The researchers caution, however, that previous discoveries in fat metabolism and appetite regulation have not always translated well from mice to humans. Nevertheless, the newly discovered enzyme may become an attractive target in developing a treatment to combat obesity, the researchers said. If excess fat can be burned before it escapes the fat cell, it can never get into the bloodstream to harm other organs, such as the heart.

-adapted from an article by Sarah Yang


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