Chewing 30 Seconds per Bite Adds About 4 kcal

One reason often given for chewing your food well is that it increases energy expenditure after a meal. Hamada and Hayashi measured this directly.

Chewing increases postprandial diet-induced thermogenesis | Scientific Reports https://doi.org/10.1038/s41598-021-03109-x

This article previously claimed the study “revealed dietary effects” and described a mechanism that does not appear in the paper. It was rewritten in August 2026 after checking the original.

What was measured

Eleven healthy young men (23 ± 1 years, BMI 21.9 ± 1.5). The test meal was 200 mL of a cocoa-flavored drink, 200 kcal (7.6 g protein, 4.4 g fat, 31 g carbohydrate). It was a liquid meal.

Three conditions were compared.

Condition	Procedure
Control	Swallow 20 mL every 30 seconds
Tasting	Hold 20 mL in the mouth for 30 seconds without chewing, then swallow
Chewing	Chew 20 mL for 30 seconds at one chew per second, then swallow

Result: energy expenditure over 90 minutes

Diet-induced thermogenesis (DIT) is the energy the body spends on digestion after a meal. The cumulative 90-minute values were as follows.

Condition	DIT (90 min cumulative)
Control	3.4 ± 0.4 kcal
Tasting	5.6 ± 0.5 kcal
Chewing	7.4 ± 0.7 kcal

Tasting and chewing were both significantly higher than control, and chewing was significantly higher than tasting (p < 0.05).

The size of the difference matters here. Chewing exceeded control by roughly 4 kcal. That is less than a single bite of rice.

And the tasting condition, which involves no chewing at all, already reached 5.6 kcal. Of the 4.0 kcal increase, 2.2 kcal — more than half — is explained not by the act of chewing but by having food in the mouth at all.

About visceral blood flow

The study also measured blood flow in the celiac artery (CA) and superior mesenteric artery (SMA) using ultrasound Doppler.

• Celiac artery: control −0.7 ± 1.1 L, tasting 5.9 ± 2.0 L, chewing 5.5 ± 2.0 L. Both tasting and chewing were significantly higher than control (p < 0.05)
• Superior mesenteric artery: no significant difference between conditions

Blood flow rose only in the celiac artery, and the chewing condition did not exceed the tasting condition (5.5 vs 5.9). This reads as a response to oral stimulation in general, not to chewing specifically.

This article previously stated that blood flow increased markedly under the increased-chewing condition. Chewing was not higher than tasting. That is a correction.

It also attributed the mechanism to a “cephalic phase response” discussed in the paper. The authors do not use that framing. It has been removed.

What the paper does raise is that upper gastrointestinal motility may have been elevated by tasting and chewing, and a possible link between oral stimulation and histamine. The authors state that the mechanism is not fully understood.

What was not measured

The study found no significant differences in the following.

• Hunger
• Fullness
• Respiratory exchange ratio (RER)

And the following were not measured at all.

• Body weight
• Body fat
• Brown adipose tissue

The authors use the word “we speculate” in their conclusion. This is not a study showing that weight goes down.

What can be said from this study

• Chewing for 30 seconds per bite significantly increases energy expenditure over the 90 minutes after a meal
• But the difference is about 4 kcal, and more than half of it is explained by oral stimulation rather than chewing
• The participants were 11 healthy young men, the meal was liquid, and measurement lasted 90 minutes
• Body weight and body fat were not measured. Long-term effects are unknown

This is not to say that spending more time chewing is pointless. But the point lies in how long the meal takes, not in the calories burned.

This site is related to the iOS app MoguExercise. The app counts chews and does not reproduce the results of this study.

---

※ This article is for informational purposes and is not a substitute for diagnosis or treatment.