Chewing food is a healthy habit
Slow eating with thorough chewing has been popularized over a century ago and it stuck. People assign a variety of beneficial effects to this habit but weight management is probably the most important one. Over the last hundred years, studies have been consistently showing that slow eating, which involves chewing food slowly and thoroughly, is an effective strategy for preventing overweight and obesity, with eating speed being associated with body composition and shape.
Chewing can increase the number of calories you burn
Studies looking at chewing explain the beneficial effects on weight through diet-induced thermogenesis (DIT), an increased heat generation in the body after food intake. This thermic effect adds to your overall body’s caloric expenditure. The problem is that, so far, we didn’t really understand how prolonged chewing induces DIT in the body. This is exactly what Dr Yuka Hamada and Professor Naoyuki Hayashi from Waseda University, Japan, set out to explore in their new study.
“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,” commented Prof. Hayashi.
An experiment focused on chewing
To find the answers, the researchers designed their new study to exclude the effect of the food bolus by involving liquid food. The study included 3 trials conducted on different days. These were the instructions participants received in those trials.
- Swallow 20 ml of liquid food normally every 30 seconds
- Keep the same liquid food in mouth for 30 seconds without chewing (prolonged tasting)
- Chew the 20 ml of liquid food for 30 seconds, one chew per second and then swallow
Variables such as hunger and fullness, gas exchange, DIT, and splanchnic circulation were measured before and after the liquid food consumption.
The study found no difference in hunger and fullness scores among the three trials. However, it found that DIT increased along with the duration of chewing.
“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,” said Prof. Hayashi.
Gas exchange, protein oxidation, and the motility of the upper gastrointestinal tract too increased with the duration of taste stimulation and chewing.
The cumulative effects of chewing are meaningful
The study highlighted that thorough chewing increases energy expenditure, which can indeed help prevent obesity and metabolic syndrome. Backed by robust science, we can consider slow eating and thorough chewing important recommendations for weight management.
“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,” Prof. Hayashi concluded.