Chewing to stay slim: How to savor your food better and dodge weight
gain
Oral stimuli during the chewing of food can help increase energy
expenditure of body and prevent obesity

Date:
January 12, 2022
Source:
Waseda University
Summary:
Chewing well helps in digestion. Chewing is also known to help
prevent obesity, possibly by increasing the thermic effect of
food consumption.

But the factors behind this heat-generating effect of chewing remain
less explored. A new study has revealed that oral stimuli, which
are linked with the duration of tasting liquid food in the mouth,
and the duration of chewing, play a positive role in increasing
energy expenditure after food intake.



FULL STORY ==========================================================================
That chewing food well makes a healthy eating habit is age-old
wisdom. Slow eating and thorough chewing help prevent obesity and weight
gain -- a view popularized a century back and tested afterward in sporadic scientific studies.

Typically, the chewing process reportedly enhances the energy expenditure associated with the metabolism of food and increases intestinal motility
-- all summing up to an increased heat generation in the body after
food intake, known as diet-induced thermogenesis (DIT). However, how
prolonged chewing induces DIT in the body remains unclear. Recently,
Dr. Yuka Hamada and Professor Naoyuki Hayashi from Waseda University,
Japan, have published a study that provides a causal link between chewing
and DIT. The study has been published in the journal Scientific Reports.


==========================================================================
DIT, also known as the thermic effect of food consumption, increases
energy expenditure above the basal fasting level -- a factor known to
prevent weight gain. Earlier, the team 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. Hayashi explains, "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. In the control trial, they asked
the volunteers to swallow 20-mL liquid test food normally every 30
seconds. In the second trial, the volunteers kept the same test food in
their mouth for 30 seconds without chewing, thereby allowing prolonged
tasting before swallowing.

Lastly, in the third trial they studied the effect of both chewing and
tasting; the volunteers chewed the 20-mL 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.

The results of this well-designed study turned up to be quite
insightful. There was no difference in hunger and fullness scores among
the trials. However, as 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. As this artery supplies
blood to the digestive organs, the motility of the upper gastrointestinal
tract also increased responding to oral stimuli during chewing.

The study highlighted that chewing well, by increasing energy expenditure,
can indeed help prevent obesity and metabolic syndrome. Hayashi concludes, "While the difference in energy expenditure per meal is small, the
cumulative effect gathered during multiple meals, taken over every
day and 365 days a year, is substantial." Backed by robust science,
slow eating and thorough chewing could be the latest recommendations
for integration into our weight management efforts.

special promotion Get a free digital "Metabolism Myths"
issue of New Scientist and discover the 7 things we always
get wrong about diet and exercise. Claim_yours_now_>>> landing.newscientist.com/what-is-new-scientist-sd/ ========================================================================== Story Source: Materials provided by Waseda_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Yuka Hamada, Naoyuki Hayashi. Chewing increases postprandial
diet-induced
thermogenesis. Scientific Reports, 2021; 11 (1) DOI:
10.1038/s41598-021- 03109-x ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220112105657.htm
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