Previous research has shown that the age-old advice of chewing food thoroughly helps protect against weight again obesity, and now a study has revealed why this is so.
Typically, the chewing process reportedly enhances the energy expenditure associated with the metabolism of food and increases intestinal motility all add up to an increased heat generation in the body, known as diet-induced thermogenesis (DIT). However, how prolonged chewing induces DIT in the body remains unclear. A study published in the journal Scientific Reports answers these questions.
DIT increases energy expenditure above the basal fasting level – a factor known to prevent weight gain. The team previously found that slow eating and thorough chewing not only increased DIT but also enhanced blood circulation in the splanchnic region of the abdomen. Although these studies linked chewing-induced-DIT with increased digestion and absorption-related activity in the abdomen, they left scopes for further exploring a few crucial points.
Senior author Prof Hayashi Naoyuki Hayashi from Waseda University explained: “We were unsure whether the size of the food bolus that entered the digestive tract contributed to the increase in DIT observed after slow eating. Also, do oral stimuli generated during prolonged chewing of food play any role in increasing DIT? To define slow chewing as an effective and scientific weight management strategy, we needed to look deeper into these aspects.”
To find the answers, the researchers designed their new study to exclude the effect of the food bolus by involving liquid food. The entire study included three trials conducted on different days. Volunteers swallow 20mL liquid test food normally every 30 seconds as a control trial. In the second trial, the volunteers kept the same test food in their mouth for 30 seconds without chewing, allowing longer tasting before swallowing. In the third trial they studied the effect of both chewing and tasting; the volunteers chewed the 20mL test food for 30 seconds at a frequency of once per second and then swallowed it. The variables such as hunger and fullness, gas-exchange variables, DIT, and splanchnic circulation were duly measured before and after the test-drink consumption.
While there was no difference in hunger and fullness scores among the trials, as Prof Hayashi describes: “We found DIT or energy production increased after consuming a meal, and it increased with the duration of each taste stimulation and the duration of chewing. This means irrespective of the influence of the food bolus, oral stimuli, corresponding to the duration of tasting food in the mouth and the duration of chewing, increased DIT.” Gas exchange and protein oxidation too increased with the duration of taste stimulation and chewing, and so did blood flow in the splanchnic celiac artery. Since this artery supplies blood to the digestive organs, upper gastrointestinal tract motility also increased in responsivense to chewing.
The study demonstrated that energy expenditure through thorough chewing, though small, could help reduce obesity and metabolic syndrome.
With robust evidence behind it, slow eating and thorough chewing could be the latest recommendations for managing weight.
Source: Waseda University