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Chewing: the missing piece

The more you chew, the less you need to eat and the more you get from your food.

We change our diets, meticulously monitoring the quality and quantity of what we eat. We change when we eat, using intermittent fasting to create a time frame for eating.

But how you eat matters just as much as when and what you eat.

Chewing your food properly has compounded effects on digestion, nutrient absorption[i], weight loss and feeling satiated quicker[ii].

Essentially, chewing more is a matter of awareness. It is actively opposing a sensitive and rushed swallowing reflex. Chewing food more means swallowing it later.

We often think of chewing, as being done by the teeth, but the tongue is the key player.

You may not have had the distinct pleasure of watching an elderly person “gum” their food, but I assure you, chewing is entirely possible without teeth. The perseverance of the human spirit reveals itself at a Burger King when dentures have been left at home.

The chewing process

Chewing is a sensori-motor process of tearing, grinding and breaking down food by mixing it with saliva and enzymes. Chewing is not an up and down, open and close motion. The four muscles involved in chewing create a rotary motion by sequencing the movements of the jaw and teeth.

The tongue controls food and liquid, moving it onto the teeth, mixing it with saliva as the food comes off the teeth and replacing it back on the teeth.[iii] Saliva contains the enzymes that break up food as well as lubricate the bolus (chewed food or liquid) for transport.

Posture and gravity: Keep your head up

Consider the impact of posture on the rotary motion of chewing. Keeping your head upright, as opposed to reclined or slouching forward, has a positive impact on muscle activation and variability of the chew. When we are upright, we take full advantage of the benefits of a rotary chew.[iv]

We tend to look down when we eat, scrolling our phone or looking at our plate. This effects posture by pulling the bolus away from the back of mouth disrupting the rotary motion of a functional chew.

Take a moment to tuck your chin against your neck, so it rests on the top of your chest. Pretend to chew by rotating your jaw clockwise and then swallow. You can feel the impact on the rotary motion and the increased effort it takes for your throat to elevate when your swallow. Compare that to the seamless rotary motion and swallow of keeping your head upright, with your chin slightly elevated. Remember this as you chew your food.  

Swallowing is the endgame

Swallowing is a reflex process that is triggered when the bolus is positioned on the base of your tongue.[v] Swallowing is a function of the autonomic nervous system, like breathing. Just like breathing, it can be manipulated but not prevented.

The tongue transmits sensory information about the viscosity of the food during chewing to determine how much food is swallowed in a single amount and how much food is moved to the cheek pouch for a swallow later[vi].

Viscosity and Volume – The trigger for swallowing

Viscosity and volume is what initiates the tongue to move the bolus towards the back of the throat to begin the swallow.[vii]

Volume is the most important characteristic in triggering the swallow reflex. The larger the bolus, the quicker the body wants to swallow it.[viii] A large bolus takes more energy to manage and it obstructs the oral cavity. It is a matter of efficiency.  

Viscosity is the result of chewing the food to the point where the tongue can register it as soft and sticky enough to pass through the esophagus. 

*This is the area where we tend to slack most when it comes to chewing our food.*

When we are rushing, looking at our phone, not realizing we are eating, or focusing on the next bite, we prematurely swallow a bolus that could be broken down much more.

Viscosity is the reason why we feel inclined to drink while we are chewing. If our mouth is too full, we reach for the drink to help us break up the bolus.

Bolus viscosity was the entire focus of the marketing campaign for “Got Milk”.

Digestion begins before we chew

We often think of the stomach and small intestines as the places where digestion takes place, however, digestion starts in the mouth with chewing.

Salivary secretion starts before we even reach for the food with our fork or fingers.

Seeing and smelling food provide the stimulus to produce saliva and enzymes in preparation for food.

Food doesn’t need to be present for this process. Just thinking of that beautifully salt-crusted T-bone with grass-fed Irish butter dripping off the crispy caramelized edges makes me drool.

Steak and butter…. life is beautiful

But eating is more than a seeing, smelling and tasting experience; food characteristics like temperate, texture and make up (e.g. fat/protein/water ratio) play a major role in how we chew and therefore digest.

 A bite is a bite, right?

Since volume and viscosity are the metrics the tongue uses to trigger the swallow, texture influences the number of chewing cycles required to prepare food to be swallowed. The harder the food, the more muscle strength involved in breaking it down, therefore the more chews involved.[ix]

Consider the difference between a mechanically soft item (cheese puff) compared to an almond. The puff breaks down instantly and effortlessly, whereas the almond requires significant chewing cycles to break down.

The crispiness of a food item results in varying resistance by the muscles involved in chewing. We chew certain textures with varying levels of intensity and for a different duration.[x]

Fat and water content are the prime factor in how food is broken down. Food with higher water counts break down quicker than foods with higher fat counts; consider the difference between a raw carrot and a steak.[xi]

Quality and Quantity: The Science of Satiation

In terms of volume, a larger bolus does not fill you up quicker. The enzymes produced from chewing don’t only break down food, they signal to the brain to produce digestive enzymes in the stomach[xii].

This is why you can’t guzzle 6 protein shakes and call it day. The shake hits the stomach before the enzymes are ready to do their work. The stomach enzymes haven’t had time to activate so nutrient absorption is decreased.

Smaller sized bolus, not small bites but ones that have been chewed adequately, release more salivary enzymes so the food is more broken down by the time it hits the battle-ready stomach… which has all its soldiers lined up to swarm the weakened bolus.

Not all bites are created equally

We often combine foods with different texture and make-up characteristics. Not only is the one of the true consistent joys in life, it creates variations in how we chew. The more complexity (textures and characteristics) we add to our bites, the more variance there is in how much we should chew our food.

This affects how we swallow the bolus, whereas when eating a bite of steak, we chew it repeatedly, focusing specifically on that one texture. The bite is also consistent because of the characteristics (fat/water ratio) of the steak.

When we drag our fork across the plate and dress the steak with fried shallots, mashed potatoes and lardons, we have complex (and oh so delightful) textures added to that bite.

Perhaps an added benefit of the carnivore diet is the consistent solitary texture of steak allows more rigorous chewing - which as we know leads to more salivary and stomach enzyme production - therefore maximum digestion.

The prescription to chew your food x amounts of bites can be misleading. Since each bite is not made equally, the amount of chewing will be different. So ideally you want to simply chew past the point of when you would normally feel ready to swallow. By focusing on your breathing, you can increase the amounting of chewing. Being present is essential here.

I have found that changing my behavior by counting has been difficult because it’s distracting when I want to focus on tasting.  I just simply go against my intuition to swallow.

I’ve also experimented with using a stop watch and simply looking at how much time has passed since I started chewing. I usually chew twice per second (rough estimate) so its about 60 chews per 30 seconds. It is amazing to see how many times the impulse to swallow appears, disappears and returns during one bite.

Fasting and Chewing – not chewing faster

When you have a reduced feeding window (like the animal you are) you want to capitalize on adding calories. You have an extended amount of time to add liquids. This is often why drinking water is discouraged during meals with intermittent fasting. Liquids take up space.  If you do feel compelled to drink while you are eating, take small sips and only use it to enhance viscosity without adding volume.

One Meal A Day (OMAD) – an unexplored feature of OMAD is the ritual and attention that modern sapiens have lost with eating. OMAD allows a person to sit and be present with their meal. Proper chewing requires time and patience. Having one massive meal to focus on, where your time is scheduled to sit and eat, enables one to put care into each bite.

Just make sure the hunger doesn’t reduce you into an insatiable animal.

The Take Away

The process of chewing more is one of going against an untrained swallow reflex. Here is the take away about how to maximize digestion by chewing more:

- Think about not swallowing yet as opposed to chewing more

-Aim to chew your food past the point where you are used to simply swallowing it down.

-Eat without distractions. Be present while you chew your food.

If you are going to be on your phone when you eat, make sure you are not tilting your head down to look at it. This forces gravity away from the back of your mouth where you should be chewing the most.

-Think Small Volume and low Viscosity

-Become aware of the food characteristics of your bites.

-Let saliva do the work so your stomach has time to get ready

It takes longer to chew a burrito bowl bite with just steak as it does steak, rice and beans (the rice and beans break down quicker therefore the bolus feels like it should be swallowed sooner)

-It is possible to chew and breathe, though you may not be used to this phenomenon from years of gorging. In order to chew your food more, you must become conscious of your breathing while you are chewing. This has the compounded effect of increasing your sense of taste.

-If you are doing intermittent fasting - don’t let hunger drive the pace of your meal.

-Chew each bite deliberately.

 Remember, the more you chew, the less you need to eat and the more you get from the food you ate.

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Sources

[i] Postprandial whole-body protein metabolism after a meat meal is influenced by chewing efficiency in elderly subjects.

https://www.ncbi.nlm.nih.gov/pubmed/17490964

Am J Clin Nutr. 2007 May;85(5):1286-92.

Rémond D1, Machebeuf MYven CBuffière CMioche LMosoni LPatureau Mirand P.

 [ii] Effect of bite size and oral processing time of a semisolid food on satiation.

https://www.ncbi.nlm.nih.gov/pubmed/19515731

Am J Clin Nutr. 2009 Aug;90(2):269-75. doi: 10.3945/ajcn.2009.27694. Epub 2009 Jun 10.

 [iii] Kahrilas PJ, Logemann JA, Lin S, Ergun GA. Pharyngeal clearance during swallow: A combined manometric and videofluoroscopic study. Gastroenterology. 1992;103:128–136.

 [iv] J Oral Rehabil. 2017 Nov;44(11):835-842. doi: 10.1111/joor.12555. Epub 2017 Sep 10.

Effect of body posture on chewing behaviours in healthy volunteers.

Iizumi T1,2, Magara J1, Tsujimura T1, Inoue M1.

 [v] Bisch EM, Logemann JA, Rademaker AW, Kahrilas PJ, Lazarus CL. Pharyngeal effects of bolus volume, viscosity and temperature in patients with dysphagia resulting from neurologic impairment and in normal subjects. Journal of Speech and Hearing Research. 1994;37:1041–1049.

[vi] Kahrilas PJ, Logemann JA, Lin S, Ergun GA. Pharyngeal clearance during swallow: A combined manometric and videofluoroscopic study. Gastroenterology. 1992;103:128–136.

[vii] Bisch EM, Logemann JA, Rademaker AW, Kahrilas PJ, Lazarus CL. Pharyngeal effects of bolus volume, viscosity and temperature in patients with dysphagia resulting from neurologic impairment and in normal subjects. Journal of Speech and Hearing Research. 1994;37:1041–1049.

 [viii] Bisch EM, Logemann JA, Rademaker AW, Kahrilas PJ, Lazarus CL. Pharyngeal effects of bolus volume, viscosity and temperature in patients with dysphagia resulting from neurologic impairment and in normal subjects. Journal of Speech and Hearing Research. 1994;37:1041–1049.

 [ix] Oral physiology and mastication

A.van der BiltL.EngelenL.J.PereiraH.W.van der GlasJ.H.Abbink

Physiology & Behavior

Volume 89, Issue 1, 30 August 2006, Pages 22-27

[x] Archives of Oral Biology

Volume 40, Issue 5, May 1995, Pages 401-403

Swallow thresholds in human mastication

J.F.PrinzP.W.Lucas

Department of Anatomy, University of Hong Kong, Li Shu Fan Building, 5 Sassoon Road, Hong Kong, Hong Kong

Accepted 14 November 1994, Available online 10 March 2000.

https://www.sciencedirect.com/science/article/pii/000399699400185E?via%3Dihub

 [xi] Archives of Oral Biology

Volume 40, Issue 5, May 1995, Pages 401-403

Swallow thresholds in human mastication

J.F.PrinzP.W.Lucas

Department of Anatomy, University of Hong Kong, Li Shu Fan Building, 5 Sassoon Road, Hong Kong, Hong Kong

Accepted 14 November 1994, Available online 10 March 2000.

https://www.sciencedirect.com/science/article/pii/000399699400185E?via%3Dihub

 

 Source List Individuals

 

1. https://www.ncbi.nlm.nih.gov/pubmed/19515731

Am J Clin Nutr. 2009 Aug;90(2):269-75. doi: 10.3945/ajcn.2009.27694. Epub 2009 Jun 10.

Effect of bite size and oral processing time of a semisolid food on satiation.

2.)  https://www.ncbi.nlm.nih.gov/pubmed/17490964

Am J Clin Nutr. 2007 May;85(5):1286-92.

Postprandial whole-body protein metabolism after a meat meal is influenced by chewing efficiency in elderly subjects.

Rémond D1, Machebeuf MYven CBuffière CMioche LMosoni LPatureau Mirand P.

 3.) Oral physiology and mastication

A.van der BiltL.EngelenL.J.PereiraH.W.van der GlasJ.H.Abbink

Physiology & Behavior

Volume 89, Issue 1, 30 August 2006, Pages 22-27

https://www.sciencedirect.com/science/article/pii/S0031938406000382?via%3Dihub#bib31

 4.) Archives of Oral Biology

Volume 40, Issue 5, May 1995, Pages 401-403

Swallow thresholds in human mastication

J.F.PrinzP.W.Lucas

Department of Anatomy, University of Hong Kong, Li Shu Fan Building, 5 Sassoon Road, Hong Kong, Hong Kong

Accepted 14 November 1994, Available online 10 March 2000.

https://www.sciencedirect.com/science/article/pii/000399699400185E?via%3Dihub

 5.) Kahrilas PJ, Logemann JA, Lin S, Ergun GA. Pharyngeal clearance during swallow: A combined manometric and videofluoroscopic study. Gastroenterology. 1992;103:128–136.

 6.) Bisch EM, Logemann JA, Rademaker AW, Kahrilas PJ, Lazarus CL. Pharyngeal effects of bolus volume, viscosity and temperature in patients with dysphagia resulting from neurologic impairment and in normal subjects. Journal of Speech and Hearing Research. 1994;37:1041–1049.

 [xii] https://www.ncbi.nlm.nih.gov/pubmed/19515731

Am J Clin Nutr. 2009 Aug;90(2):269-75. doi: 10.3945/ajcn.2009.27694. Epub 2009 Jun 10.

Effect of bite size and oral processing time of a semisolid food on satiation.