Amount of Times Food Is Chewed May Affect Waistline

Research studies to date have not examined the effects of chewing behavior on the amount of calorie intake and the release of certain hormones in the gut of normal and obese individuals. This study found that obese participants chewed less and ingested more food than lean ones. It was noted in both groups that after 40 chews of food, the ingested amount decreased by 11.9 percent compared to after just 15 chews. At 40 chews, the amount of gut hormones like ghrelin was lower and glucagon-like peptide 1 and cholecystokinin was higher, compared to that at 15 chews.

Studies suggest that eating behaviors may play a role in weight gain and obesity. Notable among these behaviors are faster eating, binge eating, gorging, and so on. No previous studies have investigated the outcome of chewing on energy intake and feeding and associated the two factors with obesity. Chewing is an important part of eating. It helps to break down the food and release certain nutrients. These nutrients then trigger the release of certain hormones in the gut, which then prepare it for digesting the food. Some of these hormones like ghrelin are associated with satiety. Too much ghrelin acts as an appetite stimulator and prevents the feeling of satiety, leading to overeating and obesity. This study attempted to compare obese and normal or lean Chinese individuals to examine the effect of chewing food on the amount of energy intake from food and its effect on gut hormone release and function.

* For the study, 14 obese and 16 normal or lean adult young men were selected.
* The first part of the study looked at the chewing behaviors of the two groups. The second part of the study examined the effects of individual chewing behaviors on the amount of energy intake and gut hormones like ghrelin, cholecystokinin, and glucagon-like peptide 1.
* In study 2, the participants were given a meal having total calories of 2,200 kilojoules (comprising an energy division of 68 percent from carbohydrates, 21 percent from fats, and 11 percent from proteins). The participants were given the food in two separate sessions – one that allowed 15 chews and another that allowed 40 chews of each 10 g of the food.

Key findings
* The results from study 1 showed that although both groups had similar bite sizes, the participants who were obese chewed less per gram of food and ingested more than their leaner counterparts did.
* Study 2 showed that with 40 chews, both groups ingested lesser food.
* On comparing the 15 and 40 chews, it was seen that both obese and lean individuals showed lesser energy intake and lower ghrelin release in the 40 chews group.
* The 40 chews group also showed that increased levels of gut hormones like cholecystokinin and glucagon-like peptide 1 signaled better metabolism of the food. This was also noted in the obese as well as the lean participants.

Next steps/Shortcomings
According to the authors, one possible shortcoming of this research was that a standard meal was offered to both the obese and lean individuals. Since personal preferences of portion size and food were not catered to, the results could have been influenced. Further studies are needed to examine appetite responses and individual preferences that dictate the effects on the gut hormones and amount ingested.

This study was the first one to compare the chewing behaviors of obese and lean Chinese participants. It was also the first study that examined the effects of fewer and more chews on gut hormone release and energy intake in both obese and lean individuals. The study showed that obese and overweight individuals tend to chew lesser and eat more than their lean counterparts. The authors conclude, “increased chewing decreases energy intake in one meal.” They speculate that this is because of the changes in the blood levels that occur due to the release of food-related gut hormones such as ghrelin, glucagon-like peptide-1, and cholecystokinin. The authors suggest that future studies and interventions that improve chewing behaviors could help to curb the rising obesity levels in the general population.

For More Information:
Improvement in Chewing Activity Reduces Energy Intake in One Meal and Modulates Plasma Gut Hormone Concentrations in Obese and Lean Young Chinese Men
Publication Journal: American Journal of Clinical Nutrition, July 2011
By Jie Li; Na Zhang; Harbin Medical University, Harbin, China


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