Digestive System > Pregastric Physiology

Chewing: All In a Day's Work

It turns out that chewing expends quite a lot of energy. Cattle spend a large part of their lives chewing. When they are consuming high quality feed, roughly 10% of the energy content of the feed is expended in the process of chewing it. Put cattle on low quality feed, such as wheat straw, and that figure jumps to about 25% of energy content (Susenbeth et al. 1998). Similar values have been measured in horses.

What about chewing gum? In a recent study by Levine and colleagues (1999), energy expenditure was measured in 7 non-obese volunteers during chair rest, and while sitting in the same chair chewing calorie-free gum at a rate of 100 MPM (mastications per minute). The basal metabolic rate at rest was 58 + 11 kcal per minute. During a 12 minute episode of chewing, metabolic rate rose to 70 + 14 kcal per minute, an increase over resting of approximately 20%. As a comparision, walking a mile in an hour basically doubles energy expenditure over resting values.

So, can chewing gum be used as a weight-control strategy? It's not a completely silly idea. The authors cited above calculated that by chewing calorie-free gum during waking hours and not changing any other aspect of energy balance, a person should lose about 5 kg of fat per year. Can you envision a gum room next to the weights room at your local health club? "Well, that's enough chewing for me, I'm off to the showers."

References and Reviews

Pregastric Digestion: Introduction and Index

Send comments to Richard.Bowen@colostate.edu