Scientists Completely Stop Diet-related Obesity in Mice

Updated | Human bodies are incredibly good at storing fat. Once an asset to our ancestors facing unpredictable meals, this skill is now helping us pile on the pounds in a nation overflowing with fast food.

By deleting an enzyme called NAMPT, researchers have made mice "completely resistant" to obesity in the face of a high-fat diet. The research, published in Molecular Metabolism, could open up avenues for innovative obesity treatments in humans.

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Burgers, fries, pizza and chicken wings. Some of the mice in this study ate a high-fat diet equivalent to humans continuously eating fast food. Matt Cardy/Getty Images

Nearly 37 percent of adults in the U.S. are obese, alongside some 17 percent of children, the CDC reports. Obesity is linked to a wide range of health problems, including heart disease, type 2 diabetes, certain cancers and stroke.

After "deleting" the NAMPT enzyme, researchers fed mice a high-fat diet and tracked their bodies' responses. 'We gave [them] a diet that more or less corresponds to continuously eating burgers and pizza. Still, it was impossible for them to expand their fat tissue," Karen Nørgaard Nielsen, the study's first author and a research student at the University of Copenhagen, said in a statement.

Instead of putting on fat tissue, the mice's fat depots grew fibrous connective tissue. When researchers took mice off the high-fat diet, the depots' fibrous tissue shrank back to normal.

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Surprisingly, the NAMPT-free mice also showed improvements in glucose tolerance in comparison to control mice. This continued after the mice returned to a normal diet. This unexpected effect may have implications for scientist's understanding of diabetes.

The research shows that both obesity and diabetes can be linked through a very fundamental mechanism, Stanley Ulijaszek, a professor of anthropology from the University of Oxford's Unit for Biocultural Variation and Obesity told Newsweek. Ulijaszek was not involved in the study.

NAMPT, scientists think, is key to metabolic function throughout the body, from the liver to the skeletal muscles. This new research shows the enzyme is crucial to the function of fat tissue. "Unfortunately, that function is efficiently storing fat," study author Zachary Gerhart-Hines, an associate professor at the University of Copenhagen, said in the statement.

"NAMPT in fat tissue was likely once an extraordinary benefit to our ancestors, but in today's society full of high-fat, calorically-dense foods, it may now pose a liability," he continued.

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Because the enzyme is believed to be crucial in many other bodily functions, it isn't safe to just decrease it in humans, Gerhart-Hines said. The risk of harmful consequences is too high.

But the research does shed light on a key metabolic mechanism. More extensive research into this enzyme, Ulijaszek said, might one day offer a "novel biomedical approach to controlling both obesity and diabetes."

This article has been updated to include comment from Stanley Ulijaszek.