But your metabolic health is central to your vitality, well-being, body shape and the likelihood of contracting serious diseases.

 This 38-year-old gentleman presented with joint pain, fatigue, and exhaustion.  He also had poor balance, resulting in falls and difficulty with memory, thinking and decision-making.  I did not expect such poor balance and dementia symptoms in someone so young.

He had sugar and salt cravings and was always hungry.  He could not lose weight despite several diets and weight management programmes.  He weighed 128kg, and his BMI was 36.4 (obesity range.)  His blood pressure was high at 150/90.

Routine blood tests reported high uric acid, diagnostic of gout, and abnormal liver function, indicative of fatty liver disease.  His cholesterol was high at 7.4, glucose at 6.3, haemoglobin A1 C (sugar control over the last three months) was prediabetic at 6.4, and vitamin D low at 21.

After advice, this gentleman swapped out processed for real food and pursued moderate physical activity and intermittent fasting.  He was able to lose weight and enjoy excellent energy levels all day.  His joint pain resolved, and he reclaimed his cognitive and liver functions.

In particular, he ate green vegetables, high in nitrites, which converted into nitric oxide (NO), enhancing energy levels and mitochondrial function.  This also benefitted his vascular health, relaxing his arteries and regulating his blood pressure.

 His symptoms were all due to his metabolism. In this blog, I will discuss how metabolism works, how your body processes food into energy, and the lifestyle choices that promote an enhanced metabolic state – thus, your optimal vitality, health, and body shape.

Your metabolism involves the processing of food to provide energy for the body to perform daily activities, eliminate body waste and produce the building blocks for the body to grow and repair itself.

You spend 70% of your energy supporting basic, life-sustaining, resting activities, such as heart beating, circulation, and breathing.  This is known as your basal metabolic rate (BMR).  The other 30% supports daily activities, such as work, housework, gardening, DIY, hobbies and sports.

Optimal metabolism is when you deliver calories to your cells to produce energy to support your health and daily activities.  Poor metabolism is when you divert calories away from your cells to be stored as fat.

Where is that “furnace”?

Many assume that there is one furnace, a body engine somewhere in the abdomen, where we make energy from food and distribute it to power our body systems.  However, energy production occurs at a cellular level.  Each cell has its independent engine, producing energy to perform daily activities.

Your body makes energy in three stages.  Bear with me as I explain them.

Stage 1, glycolysis, occurs in the cytoplasm (the liquid part of the cell) anaerobically (does not require oxygen). You break the six-carbon glucose molecules into two three-carbon pyruvate molecules, making 4 ATP (adenosine triphosphate ), the energy-carrying molecule, Spending 2 of them during the process, making a net of 2 ATP gain, in addition to 2 NADH (electron-carrying molecules) as by-products.

You further process pyruvate and NADH produced in stages two and three, which occur in the mitochondria (the cells’ powerhouses), to generate more ATP—starts by removing one carbon from the three-carbon pyruvate to make an Acetyl COA molecule. This would require B vitamins (B1, B2, B3) and alpha lipoic acid to enter the mitochondria.

Stage 2, the Crebs or tricarboxylic acid cycle, occurs in the mitochondria matrix and starts by fusing acetyl COA with another chemical, oxaloacetate, to form citric acid. This proceeds through a series of chemical reactions to make 4 ATP, 6 NADH and 2 FADH2 – the latter electron-carrying molecules are processed further in stage 3.

Stage 3, oxidative phosphorylation, occurs with adequate oxygen to produce the biggest energy yield (ATP).  During this stage, the electrons transport system harnesses electrons in NADH and FADH2 and pass them through an electrical gradient to turn the energy wheel, incorporating various factors and, at the very last step, oxygen, producing ATP, carbon dioxide (waste) and water as by-products.

Burning one glucose molecule produces 4 ATP in stage 1 (glycolysis) and 4 ATP in stage 2 (Crebs cycle) but 30 ATP in stage 3 (oxidative phosphorylation).  The latter comes from harnessing energy in 8 NADHs (each produces 3 ATP—a total of 24 ATP) and 4 FADH2 (each makes 1.5 ATP—a total of 6 ATP).  Adequate oxygen supply is the limiting factor to progress from low yield in stage 1 to the high yield in stage 3.  This highlights the importance of effective breathing to support your energy production.

Iron is essential for energy production.  The electron transport system depends on iron as an electron donor or acceptor.  Iron deficiency is common among patients who suffer from fatigue—restoring iron levels helps to resolve their symptoms.

What handicaps this system?

Mitochondria (cells’ powerhouses) produce 90% of your energy.  A fall in their numbers or deficiency of essential nutrients causes energy to plummet.  This compromises the activity of the body’s biggest energy consumers, such as the heart, brain, and muscles.

The mitochondria lose function when they have a deficiency in COQ10, a side effect of drugs like statin or birth control pills.  L-carnitine, alpha lipoic acid, B vitamins and magnesium deficiency are also common.

Toxins like herbicides and pesticides in food, heavy metals in cigarette smoke (cadmium), mercury in big fish like tuna, and dental amalgam fillings also damage mitochondria, disrupt metabolic hormones and slow energy production.

Energy shortage, in general, can cause fatigue, brain fog, poor concentration, muscle cramps, anxiety, depression and weight gain.

What can help?

High-intensity interval training (HIIT) helps to increase the number of mitochondria – a process known as mitochondrial biogenesis.  Rainbow-coloured vegetables, green tea, curcumin and sulforaphane in brassica vegetables activate the antioxidant defence system, which protects mitochondria and stimulates biogenesis.

Fasting and intermittent fasting also stimulate mitochondrial biogenesis.  A ketogenic (high fat and low carbs) diet, restful sleep, low-stress levels, sunshine and love also help the mitochondria to recover.

Adequate oxygen levels (through exercise or deep breathing) support your mitochondria to produce higher energy yield.  In adult life, we swap our original breathing (a baby’s tummy goes up and down) for rapid, shallow breathing.

Why are vitamins and minerals vital to energy production?

The digestive tract breaks food down into the smallest units.  These nutrients are absorbed into the bloodstream and distributed to every cell.  The nutrients in food can be classified broadly into macro and micronutrients.  We eat macronutrients in larger quantities, like carbohydrates, which break down into glucose – the primary body fuel.  We also break fat into fatty acids and protein into amino acids.

Digestion of food releases vitamins and minerals, which come in small quantities (the micronutrients), and these act as co-factors to activate enzymes that make energy and vitalise your body.  But, if you eat calories (sugar and processed carbs) without micronutrients, your body, in effect, says, “I’m sorry, I haven’t enough vitamins and minerals to process these calories into energy.  I have no option but to store those calories as fat.”

What determines how much you eat?

Ghrelin is the hunger hormone produced when the stomach is empty, increasing before eating and plummeting when the stomach is full.  Conversely, insulin lowers your blood sugar, causing hypoglycaemia and sometimes sugar crashes, a potent stimulus to eat.

Leptin is a hormone released from body fat that tells you to stop eating when you have had enough.  When your leptin is low, food tastes good, and you want to eat more.  Belly fat produces leptin in excess, causing leptin resistance – you have too much leptin but do not respond to it – you continue eating when you are full.

The best approach to leptin resistance is to reduce your sugar and refined carbohydrate intake, take more fibre and lose weight.

Our original real food diet was nutrient-dense, with high fibre speeding up the metabolism. In contrast, the modern Western diet is energy-dense and low in fibre and nutrients, slowing our metabolism.

Insulin is the hormone produced by the pancreas in response to the absorption of a sugar load.  It reaches every cell in the body to open the gate for sugar (the primary body fuel) to come in.  Taking the “wrong food” – simple sugars and processed carbs – gives rise to sugar spikes and crashes, comprising your energy production and raising your insulin level.  This slows your metabolism, as less sugar is delivered to your cells and more calories are stored as fat—resulting in overweight or obesity.

Our original diet provided 75-125 grams of carbs daily, while our Western diet gives more than 300 grams.

Eating protein boosts your metabolism (via the thermic effect of food.)  Quality protein can be found in organic eggs, chicken, grass-fed meat, and small-caught fish, such as salmon.  Such a diet helps you lose weight, stabilise your appetite, eat fewer calories and speed up your metabolism.

Seasoning food with hot chillies also speeds up your metabolism.  Caffeine speeds up your metabolism for two hours and usually dies off.  However, drinking green tea adds an antioxidant effect.

Age-related metabolic decline

Over time, your body becomes less sensitive to insulin; your muscle mass falls by 5% every decade and your BMR declines.  By the mid-40s, you can reach significant excess body fat and smaller muscle mass.  The ideal response is to trade fat for muscle by intermittent fasting and muscle-building exercise.  Focus on burning fat to build muscle; weight loss is the wrong goal.

You must reduce your calorie intake if your muscle mass continues to decline with age.  For example, you need 500 fewer calories at 70 than you did at 20 to maintain your ideal body weight.

What is metabolic flexibility?

Your body can burn carbohydrates (sugar) and fat as fuel for energy.  Metabolic flexibility is the ability to switch between sugar and fat with ease.  For example, you can switch from sugar to fat during an overnight fast and from fat to sugar after a meal.

Using multiple fuel sources gives you steady energy levels all day and keeps you at an ideal body weight.  It also positively impacts your health, preventing disease and slowing ageing.

Historically, our ancestors stored excess energy as fat during seasons of abundance (feast) to use during times of scarcity (famine.)

To use fat as fuel, you need to lower your insulin (the fat-storage hormone) and convert (fat) fatty acids into ketone bodies.  This occurs in the liver and is triggered by low blood glucose and insulin levels.

Ketone bodies fuel the body when glucose supplies are low, such as during fasting.  Exercising in the morning on an empty stomach is an excellent way to generate ketone bodies.

Fat is a cleaner fuel source than glucose, as it produces fewer oxidants and hence causes less muscle soreness after exercise.

Over and underactive thyroid

The thyroid is an excellent way to explain the changes in metabolism.  An overactive thyroid makes everything go fast – faster heart rate, feeling warm, perspiration, restlessness, and weight loss despite a good appetite.

In the underactive thyroid, everything goes slow–fatigue, slow pulse, low core body temperature, cold intolerance, constipation, depression, and weight gain.

The most common cause of thyroid disease is autoimmune gland damage, but simple nutritional deficiencies are also common.

You need ten essential nutrients to make thyroid hormones.  These include iodine, tyrosine (protein), vitamins A, B, C, D, E, zinc, and iron.  Vitamins D, A and C are crucial to switch on the cell metabolic activity.  You need 200 µg selenium, or 2-3 Brazil nuts daily, to activate the thyroid hormone T4 to T3.  40% of T4 activation occurs in the liver and 40% in the gut.  You cannot enjoy an optimal thyroid function without a healthy gut and liver.

Physical activity

Cardio exercises improve your cardiopulmonary fitness and oxygen delivery to your body cells, positively impacting your metabolism.  A higher muscle mass is crucial in raising your BMR and accelerating your metabolism since muscles are metabolically active and consume energy even at rest.  With an increased muscle mass, you don’t have to worry about how much you eat.

In addition, working out in the morning, when fasting, speeds up your metabolism for most of the day.  Cold showers speed up your metabolism, burning more calories to generate heat to keep you warm.

A sedentary lifestyle slows down your metabolism.  Drugs such as anti-depressants and beta-blockers slow down your metabolism.


You break down the energy-carrying molecules Adenosine triphosphate (ATPs) while working during the day, releasing adenosine.  You accumulate adenosine up to a threshold level to make you sleep.  You fill adenosine with energy during sleep and wake up when your adenosine level goes too low.  So restful sleep enhances your metabolism, while poor sleep slows it.

Working night shifts or staying late slows your metabolism and stimulates your hunger to eat unhealthy, processed food.  Clinical studies have confirmed that night shift nurses are heavier than those who work only during the day.

Chronic stress interferes with sugar delivery since cortisol (the stress hormone) counteracts insulin.  Therefore, eliminate the causes of the stress and practise stress relieving techniques boost your metabolism.

How does poor metabolism progress to disease?

When your metabolism slows down, insulin resistance diverts calories away from your cells to store as fat.  Fat accumulation around the body’s midsection results in central obesity – the first metabolic risk factor.  Your blood pressure escalates gradually due to lower levels of nitric oxide, the chemical that relaxes arteries, and later due to the build-up of cholesterol plaques (hardening of arteries).  Your insulin level escalates, raising blood sugar and triglyceride but lowering HDL (the good guy) cholesterol.

Three out of five metabolic risk factors confirm the diagnosis of metabolic syndrome, the gateway to many metabolic diseases, including diabetes, heart disease, dementia, and cancer.

So, my friends, you can see how vital your metabolic health is – that furnace in every cell.  But again, the pathway to optimal metabolic function can be found in a few straightforward lifestyle choices.  Please share your thoughts and questions by commenting on this piece, and please subscribe to the newsletter so you don’t miss further vital information.  Thank you!



A general overview of the major metabolic pathways


Modulation of mitochondria and NADPH oxidase function by Nitrate-Nitrite-NO pathways


Mitochondrial dysfunction in metabolic syndrome


Higher cellular respiration


Metabolic flexibility as an adaptation to energy resources and requirements in health and disease


Metabolic flexibility and insulin resistance

https://journals.physiology.org/doi/full/10.1152/ajpendo.90558.2008#:~:text= nce

Metabolic flexibility in health and disease