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Modified mice eat more, lose weight

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'This is a very important thing'

Some mice died

Emotion and hunger connected?

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WASHINGTON -- A new study by researchers at Baylor College of Medicine in Houston has found that genetically altered mice were able to eat up to 40 percent more food but weighed 10 to 15 percent less.

The mice were modified to lack acetyl-CoA carboxylase 2, or ACC2, a key enzyme involved in fat metabolism. While scientists are unsure of the exact chemical effect of the missing enzyme, they said mice used in the experiment appeared normal and happy, ate more, were able to reproduce and had 50 percent less body fat than normal mice.

Researchers said the study could eventually lead to human testing and perhaps one day help create a drug that helps obese people lose weight without exercise.

"This would be great for the couch potatoes -- guys who can sit on the couch, eat the potato (chips), watch the TV, without worrying about having a bigger paunch," Dr. Salih Wakil, lead researcher in the study, told Reuters.

'This is a very important thing'

That image conflicts with most conventional weight-loss advice, which asks those seeking to shed pounds to watch what they eat and exercise more. Bookshelves are packed with diets that focus on one food group, or ones that discourage eating too much sugar.

Though a possible human weight-loss drug that removes the ACC2 enzyme is likely to be years down the road, it would no doubt find a market.

At least 70 million people in the United States are overweight, Reuters reports. Obesity causes 300,000 premature deaths each year and increases the risk of potentially deadly health problems such as diabetes, coronary heart disease and kidney and gall bladder disorders.

"In the Western world," said Wakil, "this is a very important thing because of the number of obese people. Obesity is climbing, and is becoming very, very serious."

Some mice died

In the study, published in Science, researchers zeroed in on ACC2 and the related enzyme ACC1. Both are involved in producing a compound vital to the formation of fatty acids in the body, as well as fat burning.

Through genetic engineering, the scientists were able to create mice that lacked either one or the other enzyme. The mice without ACC1 all died as embryos.

However, the ACC2-lacking mice were able to eat more and lose weight. One possible reason for the increased appetite -- they were putting less of the hormone leptin in their bloodstream. Higher levels of leptin send a signal to the brain to reduce appetite.

Emotion and hunger connected?

Along with the Baylor College study, another study on weight loss was published in Science. Researchers with Howard Hughes Medical Institute, Rockefeller University, Princeton University and the University of California at San Diego said areas of the brain that control emotion and thought may also contribute to feelings of hunger.

Scientists used a green fluorescing protein to highlight connections made by leptin and a protein called neuropeptide Y. They showed that, along with signals from the body's fat cells, appetite is connected to the brain's "higher processing" centers.

The finding might also one day lead to drugs that treat obesity by altering this process, researchers said.

Until that happens, dieters have dozens of ways to try to lose weight, including the traditional methods.

In January, the U.S. Department if Agriculture released a study of more than 1,200 diet publications and concluded that if obese people eat less, they will lose weight, even if they don't exercise.

"Diets that reduce caloric intake result in weight loss," the USDA study said. "In the absence of physical activity, a diet that contains about 1,400 (to) 1,500 calories a day, regardless of ... composition, results in weight loss."

Reuters contributed to this report.

Heart Association to warn against low-carb diets
March 20, 2001
Federal diet study: Eat less to lose weight
January 10, 2001
Heart experts' advice: Eat more fish in a balanced diet
October 5, 2000
Protein diet vs. low-fat: USDA hosts nutrition debate
February 25, 2000
'Extreme eating' may equal extreme problems
September 3, 1999

American Dietetic Association
CDC - Obesity/Overweight
The North American Association for the Study of Obesity

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