When ear, nose and throat surgeon Dr Casey Means noticed her patients were presenting with conditions ending in '-itis', she realised inflammation was the root cause of their complaints.

"In medical speak, any word that ends with '-itis', means it's a condition fundamentally rooted in inflammation, the immune system revving up and causing swelling in the body," she told RNZ's Afternoons.

"Anyone who's been to an ENT doctor, they know it's a lot of -itis - it's sinusitis, thyroiditis, laryngitis, otitis, cellulitis, the list goes on and on and on.

"All of a sudden, so many years into my training, and I realised, 'oh my gosh, I'm an inflammation doctor, and I didn't even realise it'."

Metabolism is one of the most important and least understood factors in our health, she argues in her book, Good Energy: The Surprising Connection Between Metabolism and Limitless Health, which delves into the connection between inflammatory diseases and cells and the food we eat.

LISTEN ▶ Our food could be making us ill, Dr Casey Means' new book

The question then was why is there so much inflammation in our bodies?

"And so that was really an unlock for me, I know how to take a hammer to inflammation with these heavy-duty drugs like steroids, but I don't really know how to truly think about what is causing it."

Our bodies are being "revved up," she said, by industrial food production and other environmental factors.

"Our food system has changed drastically in the past 50 years, 70 percent of our calories in the US are ultra-processed foods made in a factory, these are very confusing to the body and can generate chronic inflammation.

"And on top of that, we're sleeping less, 25 percent Less than we were 100 years ago, we're barely moving our bodies, we're sitting all the time we've got our smartphones in our hands that are constantly streaming fear-inducing media, there's a lot of things in our environment that are causing a sense of threat in our bodies."

A symptom, she said, is the body telling us something is wrong on a deeper level.

"We should look with curiosity, what is the symptom? What is the body trying to tell me? In the nose it could certainly be from environmental allergens, it could be from pollen, it could be from anything triggering this, you know that we kind of associate with sinusitis.

"But it could be something deeper happening inside the body that's revving up that swelling and the chronic inflammation. It could be our diet, it could be the toxins that we're breathing in from the personal care products we're using at home, it could be any of these other elements of our modern diet and lifestyle many of which are very foreign to our bodies."

She believes we should take more ownership of our health, rather regularly outsourcing it to the medical profession, and that means knowing our key metabolic biomarkers.

Be on the lookout for things like a fasting blood sugar level, triglyceride levels, cholesterol and blood sugar levels, she said.

"You really want to know your blood pressure and your waist circumference, because these basic biomarkers together can tell us where we are on the metabolic spectrum.

"We want to see fasting glucose of under 100 milligrams per decilitre, triglyceride under 150 milligrams per decilitre, blood pressure less than 120 over 80, you want to see a waist circumference less than 35 inches in women and 40 inches in men.

"We want to see an HDL cholesterol above 40 these … just knowing a few of those biomarkers can tell us so much about how our metabolic health is."

Once we know where we stand now, we can start to address the underlying causes, she said.

"Step two is understanding all the different levers that we can pull to really follow the science and improve our metabolic health.

"This is some of the most common things that you intuitively already know. Eating, real unprocessed, high quality, fresh food filled with good nutrients, avoiding ultra-processed foods with all those unrecognisable ingredients that you know we've never heard of before."

We must move to keep the metabolism activated, she said.

"We've got to move our body throughout the day, little walks every half hour, get up and move around a little bit every half hour or so, because that keeps our metabolism active.

"Sitting at a desk, it's not working for our biology. We've got to get good sleep, we've got to clean up our environment in terms of toxins, this means filtering our water, making sure that we're not using toxic homecare products or putting toxins on our skin."

She described eating as a "matching problem".

"We meet the needs of our cells largely through the food that we're putting in our mouths. So, we're matching the needs of this machine, of the body, with what we're putting in our mouths. And when we match those things, it is the foundation of good health.

"When we get 60 to 70 percent of our calories from ultra-processed, factory-made pesticide-covered food, we are not matching the food that's going into our mouths with the needs of the cells. And so of course, there will be dysfunction."

One of the ways to understand whether the needs of the cells are being matched with the food we eat is to be aware, she said.

"Tune in to how you feel, do you feel really, really good most of the time? We should feel energetic, limitless, joyful, sharp, pretty much every day. If we're not feeling that way, there's room for improvement."

And regularly check those biomarkers, she said.

"If our biomarkers are moving into a more optimal range, specifically our metabolic biomarkers, we can pretty safely say that the food we're eating is matching the needs of these beautiful machines of ourselves."

This story was originally published by RNZ