This article previously said “it is known that the sympathetic nervous system, excited by chewing, forcibly raises the activity of brown adipocytes.” The study cited as evidence did not measure brown fat. It was rewritten in August 2026.
There’s an explanation that “chewing stimulates the sympathetic nervous system, activating brown adipocytes and burning fat.” This article carried that claim as-is. Let’s break it down step by step.
What the Cited Study Actually Measured
E03 is a study that measured chewing and postprandial energy expenditure (Hamada & Hayashi 2021). Eleven healthy young men were given a 200 kcal liquid meal and compared under three conditions.
| Condition | DIT over 90 minutes after eating |
|---|---|
| Swallow as-is | 3.4 ± 0.4 kcal |
| Hold in mouth 30 seconds (no chewing) | 5.6 ± 0.5 kcal |
| Chew for 30 seconds | 7.4 ± 0.7 kcal |
The chewing condition was highest. This much is fact.
However, this study did not measure brown adipose tissue. It did not measure body temperature, body weight, or body fat either. What it measured was energy expenditure from expired breath, visceral blood flow, and hunger/fullness ratings (no significant difference was found for the latter two).
In other words, E03 cannot be cited as a study showing that “chewing activates brown fat.” This article had been doing exactly that.
How Far the Evidence Actually Goes
Here is the breakdown.
- Chewing increases postprandial energy expenditure: Confirmed (E03, 11 subjects, 90 minutes)
- Sympathetic noradrenaline activates brown adipocytes: This is generally known physiology of brown fat. However, it was studied in contexts like cold exposure, not derived from chewing research
- Chewing activates brown fat: We were unable to find a study that measured this directly
Even if the first two points are true, the third does not automatically follow. This is where the leap happens.
The Size of the Difference
Even if chewing does increase energy expenditure, the difference observed in E03 is about 4 kcal over 90 minutes.
Moreover, the condition of simply holding food in the mouth without chewing already reached 5.6 kcal. Of the 4.0 kcal increase, 2.2 kcal is explained not by the act of chewing but by the state of having food in the mouth.
This is not a scale that can be called “rebooting the fat-burning engine.”
What This Article Previously Said
For reference, here are the statements that have been removed.
The sympathetic nervous system, excited by chewing, is known to forcibly raise the activity of brown adipocytes.
When food is swallowed without chewing, this alert does not sound, so the body does not consume the energy as heat and instead chooses the path of storing it as fat.
It has been confirmed that the rise in body temperature continues for a long time.
Body temperature was not measured. Nor was there a study, within the range this article had cited, showing this switch to “choosing the path of storing it as fat.”
Still, There Is a Reason to Chew Longer
Setting aside the energy expenditure story, increasing your chewing count extends the time it takes to finish eating. The relationship between eating pace and overeating is also covered in the review that summarizes chewing and obesity (E06).
That is the evidence that can be used here — not brown fat.
If you need specific decisions about weight or health, please consult a physician or registered dietitian. This site introduces research on chewing and has not been reviewed by a medical professional.
※ This article is for informational purposes and is not a substitute for diagnosis or treatment.
Chew Better, Live Better.
Bring science-backed insights into your daily life. MoguExercise supports your healthy eating habits.