01 August 2011

Chewing more helps you eat less

A new study finds that people who chew their food more take in fewer kilojoules, which may help them control their weight.


A new study finds that people who chew their food more take in fewer kilojoules, which may help them control their weight.

Chewing food 40 times instead of a typical 15 times caused study participants to eat nearly 12% fewer kilojoules, 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.

More chewing reduces appetite

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.

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 said, 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.

Cut kilojoule intake and lose weight

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

The 12% reduction in kJ 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 kJ intake by 12%, they would lose nearly 25kg's in one year, said Adam Drewnowski, director of the University of Washington Centre 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.

More chewing not viable for preventing obesity

"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 behaviours 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 Centres 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 US to be over R1346.50 billion per year.

(Reuters Health, August 2011)

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