Can chewing more help you eat less?

NEW YORK Fri Jul 29, 2011 5:47pm EDT

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NEW YORK (Reuters Health) - A new study finds that people who chew their food more take in fewer calories, which may help them control their weight.

Chewing food 40 times instead of a typical 15 times caused study participants to eat nearly 12 percent fewer calories, according to results published in the American Journal of Clinical Nutrition.

Jie Li and colleagues from Harbin Medical University in China gave a typical breakfast to 14 obese young men and 16 young men of normal weight to see if there were differences in how they chewed their food. The researchers also looked to see whether chewing more would lead subjects to eat less and would affect levels of blood sugar or certain hormones that regulate appetite.

Previous research has explored the connection between obesity and chewing, with mixed results. Several studies have found eating faster and chewing less are associated with obesity, while others have found no such link.

In the current study, the team found a connection between the amount of chewing and levels of several hormones that "tell the brain when to begin to eat and when to stop eating," said co-author Shuran Wang in an email.

More chewing was associated with lower blood levels of ghrelin, a hormone that stimulates appetite, as well as higher levels of CCK, a hormone believed to reduce appetite.

These hormones may "represent useful targets for future obesity therapies," Wang told Reuters Health, since regulating their levels may help people control their appetite.

The authors found no difference between the size of bites taken by obese or normal-weight men, and no link between chewing duration and blood sugar or insulin levels in any of the men.

Since the study was small and only included young men, it does not necessarily predict how extended chewing will affect the calorie intake of other people, the authors noted.

The 12 percent reduction in calories eaten by the group who chewed their food 40 times in the study could potentially translate into significant weight loss, however.

If the average person cut their calorie intake by 12 percent, they would lose nearly 25 pounds in one year, said Adam Drewnowski, director of the University of Washington Center for Obesity Research in Seattle.

But since the typical diet includes foods that are not chewed -- such as soup and ice cream -- the actual amount of weight one is likely to lose by chewing more is much less, he cautioned.

"I suppose that if you chew each bite of food 100 times or more you may end up eating less. However, I am not sure that this is a viable obesity prevention measure," said Drewnowski, who was not involved in the current study.

Despite the study's limitations, the authors say the relationship between eating behaviors and obesity is worth studying further, to help slow a growing health problem worldwide.

More than a third of American adults are obese, according to the Centers for Disease Control and Prevention (CDC). Obesity is an important risk factor for a number of health problems, including heart disease and diabetes. A 2010 study from the Brookings Institution estimated the economic cost of obesity in the U.S. to be over $200 billion per year.

SOURCE: bit.ly/mTVbpm American Journal of Clinical Nutrition, online July 20, 2011.

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