More Important Than 'Number of Chews'? Verification of Whether 'Chewing Speed' or 'Total Chewing Time' is Directly Linked to Metabolism and Obesity Prevention

In the guidance to “chew your food well,” many people tend to focus only on the absolute number of “how many times to chew (e.g., 30 chews per bite).” However, in recent physiological and nutritional metabolic research, there are two variables that are considered as important as, or even more important than, the number of chews.

These are “chewing speed (the tempo of how many times you chew per second)” and “total chewing time (the time spent on the entire meal).” This is because simply chewing 100 times at super high speed like a sewing machine and chewing 100 times slowly taking your time will result in completely different models of response for hormones secreted in the body and the sympathetic nervous system.

The Trap of “Chewing at Super High Speed (High-Speed Chewing)”

When only the number of times is set as a goal, many people unconsciously think, “Let’s achieve the quota quickly and swallow,” and try to crush the food at a very fast speed (brisk high-speed chewing) of 2 to 3 times per second.

• Risk of Sympathetic Nervous System Hypertonia: Excessive high-speed chewing exceeding a certain pace deviates from the realm of rhythmic movement (serotonin secretion) that brings relaxation, and may be input to the brain as “impatient” or “aggressive” stress signals. As a result, the sympathetic nervous system excessively spikes, which may lead to transient elevations in blood pressure (related to the metabolic and cardiovascular systems in E06).
• Insufficient Mixing with Digestive Enzymes: Even if physical crushing (making the particle size smaller) is possible (E05), if the “time” spent chewing overall is short, the time the food stays in the mouth is overwhelmingly insufficient. As a result, the other important task of chewing, which is to sufficiently mix (emulsify) the food with a large amount of saliva (amylase), is sent to the stomach uncompleted.

”Total Chewing Time” Correlates with Metabolic Indices

On the other hand, what is thought to be more strongly correlated with the prevention of obesity and the maximization of “Diet-Induced Thermogenesis (DIT: the phenomenon where body temperature rises after eating)” is the “total chewing time (the length of time until swallowing).”

• Stimulation Time of the Brain’s Central Nervous System: The signals to the sympathetic nervous system and histamine nervous system that activate DIT (E03) depend on “how long there has been continuous stimulation in the oral cavity.” It is suggested that taking 30 seconds to chew 30 times thoroughly (at a pace of 1 chew per second) increases the “input integral value (depth of stimulation)” of the stimulation to the brain compared to finishing 30 chews in 10 seconds, and as a result, postprandial energy expenditure significantly jumps (body temperature rises).
• Initial Response Time of Incretins (GLP-1): There is a certain time lag from when the food stimulation reaches the digestive tract until the lean hormone “GLP-1,” which is secreted from the gastrointestinal tract and suppresses rapid spikes in blood sugar levels, is secreted. Taking your time to chew slowly functions as a perfect buffer where this GLP-1 secretion fully starts up and “physically buys time until the pancreas’s insulin preparation is complete.”

Designing an Ideal “Chewing Speed Index”

So, what kind of “tempo” and “time” should we be conscious of in our daily meals?

• Optimal Tempo is “1 Chew per Second”: Be conscious of chewing at a relaxed tempo (about 1 time per second), which is the same as or slightly slower than your heart rate. This pace is the most suitable “physiological rhythm” for stabilizing the autonomic nervous system and secreting saliva.
• The Goal is “20 Minutes or More per Meal”: Fast eaters finish their meals in less than 10 minutes. It takes at least 20 minutes for the brain’s satiety center to receive the signal that “I have eaten.” Imposing on yourself the “time axis constraint” of “looking at the clock and not leaving the dining table for 20 minutes (distributing the pace slowly)” in addition to the number of times (30 times) becomes an absolute condition to fundamentally break the chain of worsening metabolic syndrome (E06).

If you get tired of “counting the number of times,” try focusing only on “slowing your chewing speed to extreme slow motion (extending total chewing time)” at first. Just doing that should dramatically shift your body’s hormonal response in the right direction.