Obesity Is Linked to Stress Hormone, Scientists Say

By Simeon Bennett

July 2 (Bloomberg) -- Scientists say they have found a link between stress and obesity, which offers hope in treating the 1.6 billion adults who are overweight worldwide.

The brain under stress releases a hormone that activates a gene in fat cells, causing them to grow in size and number, according to a study published today in the journal Nature Medicine. Scientists found stressed mice gained twice as much fat as those fed the same high-calorie diet. The stressed mice didn't gain weight when the gene was removed or blocked.

The World Health Organization estimates that the number of overweight adults globally will rise to 2.3 billion by 2015 from 1.6 billion adults in 2005. One third of Americans are too heavy and the condition accounts for about 10 percent of U.S. health costs. Obesity, which can cause complications including diabetes and heart disease, is getting worse globally, the WHO says.

``It's a major breakthrough in understanding how energy can be diverted into fat cells,'' said Herbert Herzog, neuroscience program director at the Garvan Institute of Medical Research in Sydney, which participated in the research.

The hormone, called neuropeptide Y, works like a key that unlocks so-called Y2 receptors in the body's fat cells, Herzog said, then pumps energy into them. Blocking the receptors stopped fat cells growing and multiplying, a technique that should work in humans as it does in mice, he said in a June 28 interview.

Next Step

Herzog said the next step was for drugmakers to develop treatments that block the receptors in humans. Some compounds have been shown to work in laboratories or animals, but none have yet been tested on people, he said.

Researchers stressed the mice either by exposing them to cold or keeping them together with more aggressive mice, Herzog said. Other scientists taking part in the study came from Georgetown University in Washington and the Slovak Academy of Sciences in Bratislava, Slovakia.

The ranks of the obese have swelled around the world as diets incorporate fattier, sugar-filled foods and people cut back on physical activity in response to changing work and transportation patterns.

Doctors and public health officials should be bracing for a wave of chronically ill young adults with weight-related ailments that include diabetes and heart disease, researchers at Harvard University in Boston said in a study published on June 27.

To contact the reporter on this story: Simeon Bennett in Singapore at sbennett9@bloomberg.net

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