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What is metabolic health, really?
When people hear the term "metabolic health", they often think of weight. But it is much more than that. I'm a lifestyle medicine doctor in Cape Town, and metabolic health is one of the core areas of focus in my practice. In this post, I'll explain what it really means, how it becomes dysfunctional, and what you can do to improve it.
So, what is metabolic health?
"Metabolic health" is a bit of a buzzword, but the formal definition is simple. It is the collection of all the internal processes your body uses to convert food into energy, store and use nutrients, and keep you functioning.
Every second of every day, your body is working to:
Regulate blood glucose
Process fats
Maintain blood pressure
Manage energy balance
Extract and use nutrients from food
Keep your organs working properly
And more!
When it runs well, you feel well. You have steady energy, you sleep better, and your body composition is easier to manage. When it starts to drift, the signs are easy to dismiss as “just getting older” or "just being stressed": afternoon crashes, creeping blood pressure, brain fog, cravings and more.
Importantly, metabolic health is not the same as your weight, your BMI or your metabolic rate. Many people think that if they're at a normal weight or BMI that they are automatically metabolically healthy, but this simply isn't true. Metabolic health doesn't discriminate. You may be thinking "but I feel fine", but one of the biggest misconceptions about health is that if you feel well, you must be healthy. You can still "feel fine" while your blood pressure and cholesterol are very high, because they don't really cause any symptoms until there is advanced disease.
And unfortunately, the human body doesn't always send us a polite notification when something starts going wrong, sometimes it waits the engine to break before turning on the warning light.
What are the components of metabolic health (and how do we measure them)?
Blood glucose regulation
When you eat carbohydrates, they are broken down into glucose, which enters your bloodstream. Your pancreas then releases insulin, a hormone that helps your cells take up and use that glucose. When this system works well, your body regulates blood glucose without needing excessive amounts of insulin.
If you become insulin resistant, insulin is still released in response to rising blood sugar after a meal, but it doesn't work effectively at a cellular level. Your cells struggle to take up glucose from the blood, which can eventually lead to type 2 diabetes.
To see how well your body is managing blood glucose, we can look at:
HbA1c: a three-month indication of your blood glucose control
Random glucose: your blood glucose at any point in the day
Fasting glucose and fasting insulin: your levels first thing in the morning, before eating. From these two numbers we can calculate your HOMA-IR (insulin resistance score) and your QUICKI index (insulin sensitivity score)
These numbers tend to change long before type 2 diabetes is established, which is why I include them in all annual blood tests.
Fat processing
Your body needs fat. It is essential for cell membranes, hormone production and energy storage. But excessively high triglycerides, for example, can indicate that your body isn't handling energy and fat metabolism well. This is often the result of a poor diet, a sedentary lifestyle and other lifestyle factors.
Here we look at your lipogram (lipid panel):
Total cholesterol: the total amount of cholesterol in your blood
LDL cholesterol: often called "bad cholesterol". This is the particle that forms plaque in artery walls, leading to heart disease and strokes
HDL cholesterol: often called "good cholesterol". It helps pick up excess cholesterol around the body and returns it to the liver to be processed and removed
Triglycerides: a type of fat in the blood that the body uses for energy. Elevated levels are a key marker of metabolic health and are closely linked to insulin resistance
More advanced lipid testing, such as ApoB and lipoprotein(a), can also be done (which I highly recommend).
Blood pressure
Your cardiovascular system needs enough pressure to deliver blood throughout your body, without placing excessive strain on your blood vessels, heart and kidneys.
Normal: 120/80 or below
Stage 1 hypertension: 130–139 / 80–89
Stage 2 hypertension: above 140/90
One of the key drivers of high blood pressure today is too much sodium. Sodium pulls water into the arteries, which increases the volume of blood that has to be pumped through the same-sized vessels, and that raises blood pressure.
Energy balance and body composition
BMI is a population-level screening tool. It tells us a little more than weight alone, but it says nothing about your body composition: how much of you is muscle, bone, fat, water and so on.
The gold standard for assessing body composition is a DEXA scan, which is essentially a low-dose X-ray. The body composition scales you see at the gym (like InBody scans) are less accurate, but still better than weight alone. With these machines, trends over time matter more than any single reading.
When assessing body composition, we look at three main things:
Muscle mass: muscle is one of the major tissues responsible for clearing glucose from your bloodstream and maintaining insulin sensitivity. Muscle mass peaks around age 30 and then declines by about 1% per year, and at an faster rate after 50, unless you actively work to build and maintain it.
Fat mass or body fat percentage: this is not just about aesthetics. Excess fat tissue produces pro-inflammatory messenger molecules that can cause chronic inflammation, which can accelerate many chronic diseases, including heart disease, diabetes and even certain cancers.
Visceral fat: the fat around your organs. It is associated with worse metabolic health than subcutaneous fat, the fat under your skin that you can pinch.
Nutrient status
This one isn't strictly part of the definition of metabolic health, but I include it in my assessments. It refers to your body's ability to absorb and use key nutrients.
Some blood tests I often order include:
Vitamin B12, and sometimes homocysteine and methylmalonic acid to assess for a functional vitamin B12 deficiency (when your B12 level looks normal, but you don't have enough active B12 at a cellular level).
Iron studies, including ferritin which is your iron storage protein that we use to diagnose iron deficiency.
Folate, also known as vitamin B9.
Vitamin D, especially during/coming out of winter months.
Magnesium, calcium and zinc - deficiencies are rare but many people (especially women) may have suboptimal levels.
Having enough of all of these nutrients is vital for good energy levels and healthy cellular function.
Organ function and hormone levels
Your liver, pancreas, thyroid and kidneys all play important roles in metabolic regulation. That is why I look at liver and kidney function tests and thyroid hormone levels when assessing metabolic health. Additional hormone levels may be tested when appropriate, but this is not necessary for every single person.
Testing may include:
Thyroid function tests: thyroid stimulating hormone is a common initial test to screen for thyroid dysfunction, but individual thyroid hormones (including T3 and T4) as well as thyroid antibodies can also be done.
Kidney function tests: which include electrolyte levels like sodium and potassium, waste products filtered by the kidneys like urea and creatinine, as well as your estimated kidney filtration rate, which is a measure of how well your kidneys are doing their main job.
Liver function tests: which includes protein levels in the blood (both total protein and specific types of proteins like albumin and globulin), waste products from the liver like bilirubin, and several liver enzymes.
Sex hormone tests: which includes estradiol, progesterone, total and free testosterone, and several others, where appropriate.
All of these components are interconnected. Once we see dysfunction in one area, the risk of dysfunction in others increases.
What causes metabolic dysfunction?
Diet
Metabolic dysfunction can result from too much energy intake, a suboptimal composition of that intake, or both. That means too many calories for your needs, and/or a poor-quality diet that doesn't provide enough nutritional value to support your health.
Everyone focuses on protein, which is important, but so are complex carbohydrates, fibre and micronutrients. It also helps to limit or avoid ultra-processed foods, processed and red meat, and alcohol.
Inactivity
A sedentary lifestyle drives insulin resistance and weight gain, which leads to metabolic dysfunction. Three things matter when it comes to movement:
Resistance training to build muscle mass and strength, which are key for longevity and insulin sensitivity.
Aerobic exercise that gets your heart rate up, which is important for cardiovascular health.
Regular movement throughout the day to avoid prolonged sitting.
An hour in the gym is great, but it doesn't make up for eight hours at a desk if you really want to optimise your metabolic health.
Poor sleep
Sleep can feel like a waste of time because you're not actively doing anything, but many processes vital to your health take place while you sleep. After just one night of restricted sleep, hunger hormones are higher the next day, insulin sensitivity is reduced, and you may crave less healthy food. This is a key component of weight loss that many people neglect to include in their plan.
Chronic stress
Chronic stress affects glucose regulation, sleep and health behaviours. Common coping mechanisms include smoking, vaping, drinking alcohol, binge eating and binge-watching TV. These can harm your metabolic health, and they don't address the root stress or improve your response to it. This can create a vicious cycle: stress leads to poor coping behaviours, which lead to more stress, and so on.
The good news
Because so much of metabolic dysfunction is driven by lifestyle behaviours, metabolic health can often be improved by targeting those behaviours: how you eat, move, sleep and manage stress.
Ready to optimise your metabolic health?
If you want a deeper understanding of your health and want to optimise your metabolic health for longevity, and you're in South Africa, you can book an in-person or telehealth consultation with me at www.DrRoxieBecker.com or email admin@DrRoxieBecker.com.
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