Our modern, quick-fix, processed diets are reducing the amount of chewing we do, and the effect is profound and surprising. Claire Turnbull explains.
When my son was four, he was rushed by ambulance to Starship Children's Hospital after complications with surgery left him unable to breathe on his own. For a tense few days, we watched as he lay in bed, relying on noisy machines to keep him alive.
Now 12, my son continues to struggle with his breathing. Through this experience, combined with my own breathing difficulties following a brain injury in 2020, I became deeply interested in the mechanics of breathing and recently embarked on study to become a certified breathing coach, to sit alongside my training in nutrition, fitness and positive psychology.
While I expected to learn more about how breathing can exacerbate stress and fatigue, as well as the impact of exercise, I didn't expect it to overlap so much with nutrition. But it turns out that recent changes in how and what we eat, while reshaping our waistlines, have also been quietly altering our mouths, our teeth, and our airways, with a real impact on how many of us breathe.
We were built to chew
As omnivores, humans are designed to be able to eat both plants and animals. Our teeth and the structure of our digestive system tell that story. Canines for tearing, molars for grinding, and a digestive tract equipped with a variety of enzymes designed to break down a wide range of foods.
As well as chewing meat, many of our hunter gatherer ancestors would have spent a significant portion of each day tearing, grinding and chewing their way through roots, tubers, seeds, and fibrous plant matter, when they were available. The Hadzabe people of Tanzania, one of the last remaining hunter gatherer societies who still eat like our ancestors, are estimated to be getting around 90-100g of fibre a day from the plant material they eat. This is a far stretch from the average New Zealander, at 20 grams. While our guidelines don't recommend that we aim for as much as 90g, most of us need a lot more fibre than we are currently eating.
Our lack of chewing matters more than most of us realise. When it comes to breathing, inadequate chewing over time is believed to be influencing jaw development, tooth positioning, and airway function. From a nutrition perspective, chewing has a significant impact too, not only on our digestive system but also influencing what and how much we can eat in a profound way.
Engineering the effort out of eating
There is no doubt that many of the changes we've made to food over thousands of years have been enormously beneficial. Cooking, milling grains, soaking legumes, and fermenting foods have made many foods safer, easier to digest and, in some cases, more nutritious, as well as improving the availability of our food supply.
Soft foods also have an important place. For older adults with poor dentition, people recovering from illness or those struggling with their appetite, softer meals can make the difference between meeting nutritional needs and not. And for all of us, nourishing soup packed with vegetables and lentils is a perfectly good thing.
So, the problem isn't food processing itself. It's how far we've taken it.
Walk through any supermarket and much of what fills the shelves bears little resemblance to the foods it originally came from. Breakfast cereals that dissolve almost instantly on the tongue; puffed snacks, liquid breakfast drinks, soft white bread, instant noodles, protein bars, and countless ultra-processed snack foods require very little chewing. These can often be sipped, squashed, or swallowed within minutes.
Food manufacturers spend enormous resources making food as palatable and easy to eat as possible, the right texture, the right melt, the right crunch. Why? Because when food is engineered this way, it tastes good and you can eat more of it faster than less processed food.
Enjoying some of these foods occasionally is not a problem. It's when they become the foundation of your diet that things start to go wrong.
Same label, different impact
The way a food is processed can change how it behaves in your body, even when the nutrition label looks the same. Almonds are a good example. Whole almonds and finely ground almonds may have the same calories listed on the packet, but your body handles them differently.
When you eat whole almonds, their natural structure stays partly intact as you chew and digest them. This means they take more time and effort to break down; they can help you feel fuller, and some of their fibre-rich structure continues through the gut where it can support your gut bacteria.
When almonds are ground into a fine powder, a lot of that natural structure has been broken down before you eat them. This makes them quicker to digest and reduces the amount of structured fibre that becomes available to your gut bacteria, so they're less beneficial to gut health.
Calorie-wise it makes a difference too. Research by Professor Sarah Berry at King's College London highlighted that the amount of energy you access when you eat almonds whole is less than when they're ground, as around 30% of the calories pass through unabsorbed, so you end up metabolising roughly 128 calories for every 170 listed.
The form that food comes in genuinely changes how your body experiences them, and that is something a nutrition label won’t tell you.
The role of chewing in appetite
One of the problems with soft and ‘low chew’ food is how much it disrupts the built-in system that helps us manage how much we eat.
When we take the time to prepare food, this process primes the body for digestion. The anticipation of food, the smell of it, and the interaction with it – all of this gets your saliva going and signals the pancreas to prepare for incoming nutrients, priming insulin release as part of what is known as the cephalic phase response.
Next, when food arrives in the stomach, stretch receptors register its volume and communicate with the brain that food has arrived.
Around 90 minutes after eating, as food moves into the small intestine, hormones are released, including GLP-1, to signal that nutrients have arrived and are ready to be absorbed. GLP-1 is the hormone that drugs like Ozempic and Wegovey mimic.
Finally, if you have eaten enough fibre, gut bacteria in the colon ferment it and trigger another wave of satiety signals that can keep you satisfied for hours.
Highly processed and soft foods, which require very little chewing and often have low volume compared to whole fruits, vegetables and grains, can disrupt every stage of this cascade. Skip the food preparation, drink your lunch, eat something that dissolves before it even reaches your stomach – and you have bypassed the first stage already. Eat quickly enough, and the fullness signals never get a chance to catch up. Research from the US National Institutes of Health found that people eating ultra-processed diets consumed around 500 more calories per day than those eating minimally processed diets, even when other nutrients were matched.
The fibre illusion
Many processed and packaged foods now prominently feature fibre on their labels: snack bars, cereals, protein balls, smoothies, even yoghurt! While some added fibre is better than none, not all fibre is equal, and the form it comes in matters enormously.
There are three main types of fibre. Insoluble fibre, found in the skins of fruit and vegetables, wholegrains and legumes, adds bulk and keeps things moving through the digestive system. Soluble fibre, found in oats, apples, lentils and flaxseeds, forms a gel in the gut, slowing digestion and helping you feel fuller for longer. Resistant starch, found in foods like slightly underripe bananas, cooked and cooled potatoes and legumes, acts as a prebiotic, feeding beneficial gut bacteria. All three play important roles, and the best dietary sources provide a natural mix of them.
The fibre most commonly added to processed foods is inulin, a type of soluble fibre extracted and added in concentrated form. It does have benefits for gut bacteria, but it is not the same experience for your body as eating fibre from real, minimally processed foods.
Wholefood fibre arrives packaged within plant structure with water, minerals, polyphenols, antioxidants and, critically, it requires the physical act of chewing. When your gut bacteria ferment that wholefood fibre, they produce short chain fatty acids that trigger the release of your body's own natural satiety hormones, keeping you satisfied long after the meal is done. A fibre-enriched bar can contribute to your daily total, but it does not replicate that process. The gut knows the difference, even if the label suggests the fibre content is the same.
Children need to chew
Children need safe, age-appropriate opportunities to bite, chew, and manage a range of textures and, unfortunately, they don't always get them. Children in New Zealand are getting nearly half of their energy from ultra processed foods by age one, and over half by age five, according to a University of Otago study of more than 800 Dunedin children. Yoghurt pouches, crackers, cereals and soft snacks were among the biggest contributors to these processed diets.
While softer foods are appropriate when babies first start eating at around six months, the goal is to progressively move toward family foods, not to keep children on smooth, easy options indefinitely. As they grow, being mindful that quick and easy soft snacks are not a substitute for food that actually asks something of their mouths is important. Offer safe textures. Let them chew.
What you can do to improve your chewing
This is not about feeling guilty for eating mashed potatoes or enjoying a smoothie. It is about reflecting on how much processed food you're having and asking a simple question more often: am I giving myself enough opportunity to chew whole food?
- Go for whole fruits with the skin on as often as possible.
- Enjoy more raw vegetables and, when you cook them, aim to keep some bite in them
- Mostly look to eat nuts and seeds whole, rather than ground.
- Include more pulses like lentils, chickpeas, kidney beans, black beans in your diet.
- Opt for less processed grains – brown rice, large chunky rolled oats rather than quick-cook varieties, grainy breads and crackers with visible grains and/or seeds, and barley, quinoa and buckwheat to mix things up.
- Slow down for at least one meal a day – sit, chew, pause, notice flavour.
- Give yourself enough time to eat – if you tend to be done in five minutes, can you stretch it to ten or a little longer?
- Remember to breathe during mouthfuls.
- When it comes to packaged foods, look beyond the fibre number on the label and ask where that fibre is coming from.
- If you have kids, reflect on whether they are getting enough opportunity to chew.
Claire Turnbull is a registered nutritionist with an honours degree in dietetics, a wellbeing educator and author.
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