Metabolic health is how well your cells make and use energy. It is the foundation of every function in your body: conceiving, holding or losing weight, the energy you have at four in the afternoon, and how well you age. A small number of routine blood markers can show how well that system is working, provided they are read for more than whether a result is normal.

Why normal is not the same as optimal

Most blood results are reported against a reference range. Reference ranges are useful, but they are not always the same as optimal in metabolic health.

Dr Mayoni Gooneratne, PHC's Chief Functional Medicine Officer, encourages people to look beyond normal or abnormal and understand three things: how a marker is trending over time, the context around it, and how markers relate to one another.

These are the five blood markers she would want everyone to know.

1. HbA1c

HbA1c gives an estimate of your blood's average exposure to glucose over the last three months. It is useful because it can identify progression towards prediabetes and diabetes.

It has limitations. You can have a normal HbA1c and still experience peaks and crashes in your glucose through the day. In Dr Gooneratne's words, "it's a starting point, not the whole story."

2. Fasting insulin

Fasting insulin is one of the most underused markers in routine conversations about metabolic health.

Glucose can stay within range for many years because the body is busy making more and more insulin to keep it there. By the time glucose actually rises, the system has probably been under a lot of pressure already.

Read alongside fasting glucose, fasting insulin can show signs of insulin resistance much earlier.

3. Triglycerides

Triglycerides are the fats circulating in your blood. High levels can be associated with excess energy intake, insulin resistance, alcohol, poor glucose handling and, potentially, a fatty liver.

They are not simply a reflection of how much fat you eat. Triglycerides tell us a great deal about how the liver is handling carbohydrate and managing energy balance overall.

4. HDL cholesterol

HDL is not interpreted in isolation. It is read alongside triglycerides. A high triglyceride-to-HDL ratio, for example, is a strong signal that insulin resistance or reduced metabolic flexibility is developing.

As Dr Gooneratne puts it, the aim is "not to diagnose one condition, it's to look at patterns."

5. Liver enzymes: ALT and GGT

The liver is central to metabolic health. It manages energy storage, lipid processing, detoxification and inflammation.

Liver enzymes such as ALT and gamma-GT (GGT) can rise for many reasons. They can also stay within the normal range while still showing early signs of metabolic strain. A mildly raised ALT or gamma-GT in someone with central weight gain, high triglycerides, poor sleep and anxiety is a good place for a clinical conversation to start.

A sixth marker worth knowing: the neutrophil-to-lymphocyte ratio

The neutrophil-to-lymphocyte ratio (NLR) is not strictly a metabolic marker, but Dr Gooneratne considers it a powerful marker of accelerated ageing.

She looks for a ratio of around one. As we age, lymphocyte numbers can decline at an accelerated rate. That leaves a relative increase in neutrophils, and the ratio rises.

Reading the markers together

No single marker tells the full story. Read together, over time and in the context of how you live and feel, these markers show how well your whole system is working. That is the approach behind the PHC Metabolic Audit, which reads more than sixty blood markers alongside two weeks of continuous glucose monitoring.

Frequently Asked Questions

Which blood tests show metabolic health?

Five markers give a strong picture of metabolic health: HbA1c, fasting insulin, triglycerides, HDL cholesterol and the liver enzymes ALT and gamma-GT. They are most useful when read together, tracked over time and interpreted in the context of how a person lives and feels, rather than judged one by one as normal or abnormal.

What is the difference between a normal and an optimal blood result?

A normal result sits within the laboratory's reference range. Reference ranges are useful, but in metabolic health they are not always the same as optimal. A result can be within range while still showing early strain, particularly when it is trending in the wrong direction or when it is read alongside other markers.

What does HbA1c measure?

HbA1c estimates your blood's average exposure to glucose over the last three months. It helps identify progression towards prediabetes and diabetes. It does not show day-to-day swings, so a person can have a normal HbA1c while still experiencing glucose peaks and crashes. It is a starting point rather than the whole picture.

Why is fasting insulin important for metabolic health?

Glucose can stay in range for years because the body produces more and more insulin to keep it there. Fasting insulin shows that extra effort before glucose rises. Read alongside fasting glucose, it can reveal insulin resistance earlier, which is why it is one of the most underused markers in routine conversations about metabolic health.

What does the triglyceride-to-HDL ratio show?

The triglyceride-to-HDL ratio compares the fats circulating in your blood with your HDL cholesterol. A high ratio is a strong signal that insulin resistance or reduced metabolic flexibility is developing. It is used to look at patterns across markers rather than to diagnose one condition.

Can liver enzymes show early metabolic problems?

Yes. The liver is central to energy storage, lipid processing, detoxification and inflammation. Liver enzymes such as ALT and gamma-GT can rise for many reasons, and can show early metabolic strain even within the normal range, particularly alongside central weight gain, high triglycerides and poor sleep.

What is the neutrophil-to-lymphocyte ratio?

The neutrophil-to-lymphocyte ratio (NLR) compares two types of white blood cell. It is not strictly a metabolic marker, but it is a useful marker of accelerated ageing. As we age, lymphocyte numbers can fall faster than expected, which raises the ratio. Dr Mayoni Gooneratne looks for a ratio of around one.