The complete Test, Don't Guess series — clinical investigation, practitioner reality, and the body you are living in. All available now on Amazon.
The Test, Don't Guess series grew out of 37 years of clinical practice — and from a single observation that has never changed: the gap between what standard investigation finds and what is actually happening is where most chronic health problems live.
The four books address that gap from four different angles. Together they form a complete clinical philosophy. Each stands alone. Metabolic Natures — Book 4 — is now available on Amazon.
The foundational book. Why standard testing is designed to miss functional dysfunction. What five tests — blood chemistry, GI-MAP, DUTCH Plus, Organic Acids, and food sensitivity — reveal that a standard panel cannot. How to read results to optimal rather than just normal ranges. The framework that connects findings into a protocol.
"Your tests are normal. But normal is not the same as optimal — and the distance between those two points is where most chronic health problems live."
The test results are not the hard part. Getting someone to act on them — consistently, sustainably, in the actual Tuesday morning of their life — that is the hard part. And nobody puts it in the course materials. The psychology of behaviour change, the neuroscience of recovery, the conversations that determine whether a protocol works. The human layer of functional medicine.
"The test results are not the hard part. Getting someone to act on them — consistently, sustainably, in the actual Tuesday morning of their life — that is the hard part. And nobody puts it in the course materials."
Your body is not seven separate problems waiting for seven separate specialists. It is one interconnected system — and the fatigue, the hormonal disruption, the weight that won't shift, the gut symptoms that persist despite the perfect diet — these are not mysterious. They are the predictable downstream consequences of upstream disruptions that standard investigation doesn't look for. This book looks for them.
"Your body is not seven separate problems waiting for seven separate specialists. It is one interconnected system — and its disruptions are predictable, not mysterious, once you know where to look."
Six types. One framework. Test-confirmed — and what the data actually shows about why nutrition is individual
Why does every diet work for someone and fail someone else? The answer lies in metabolic individuality — and it is testable. Metabolic Natures identifies six distinct metabolic types defined not by questionnaire, but by the physiological patterns that show up in functional testing: blood chemistry, organic acids, and DUTCH hormone data.
The six types — Kinetic, Grounded, Catalyst, Endurance, Adaptive, Calibrated — represent the spectrum of how human metabolism actually operates. Each has a recognisable test signature, characteristic symptoms, and a dietary approach that works with the system rather than against it. This is the framework the field has been missing.
"The question was never which diet is correct. The question was always which metabolic system it was operating on — and whether those two things were compatible."
The Starter Edition of Test, Don't Guess is currently in production as an audiobook — narrated by Stephen Duncan using a professional voice clone. 20 chapters, 23,000 words. For the commute, the walk, the gym. Available on major platforms when released.
If you have NHS blood results, private lab results, or have already run a GI-MAP, DUTCH Plus, or OAT — the Detective Health interpretation guides give you the clinical framework to read them properly. Each guide covers one test in depth: optimal rather than normal reference ranges, what the markers mean, and how to connect findings to symptoms. Available at detective-health.com/products. If you want to run a test from scratch, ask at your discovery consultation.
See the Interpretation Guides →The TDG Five-Test Programme is the clinical investigation the books describe — applied to you, your results, your biology.