Why Different Body Frame Types Have Different Healthy Insulin Resistance Levels
How to know when yours is too high — and why standard tests may be misleading you
The science validates the direction of this framework — that lean constitutional types have lower normal baselines across all these markers, and that the universal thresholds were largely derived from heavier populations and therefore systematically miss early-stage insulin resistance in thinner people.
But no published paper has ever set constitutional body-type specific reference ranges. What you are reading here — a clinical table of thresholds for HOMA-IR, TG/HDL, and blood pressure calibrated to your frame type — does not exist in any published form elsewhere.
Insulin resistance is almost never measured by a GP or conventional doctor. It is not part of standard blood tests in the UK, the US, or Europe. Most people with insulin resistance have no idea they have it — and neither does their doctor. A standard cholesterol panel, a fasting glucose, even an HbA1c: none of these directly measures insulin resistance. It requires a fasting insulin level alongside fasting glucose to calculate HOMA-IR — a test that is rarely requested and rarely explained.
On the rare occasion when insulin resistance is tested, the result is compared against a single universal threshold: below 2.0 on the HOMA-IR is considered fine, above it is flagged. The same line is drawn for everyone — lean, heavy, and everything in between.
A naturally lean, light-framed person runs at a completely different metabolic baseline than someone with a naturally larger, heavier build. Applying one threshold to both means lean people with early insulin resistance are routinely told their numbers are normal, and are only identified when the damage has progressed considerably further. Meanwhile, heavier-framed individuals may be flagged as borderline when they are still within their own healthy range.
The same logic applies to the TG/HDL cholesterol ratio — a widely used surrogate marker for insulin resistance — and to blood pressure. All three markers have a natural baseline that differs by constitutional frame type, and all three need different thresholds to be clinically meaningful.
The Three Constitutional Frame Types
This framework uses three body frame types drawn from both modern metabolic research and the 5,000-year-old Indian medical tradition of Ayurveda, which identified these constitutional patterns millennia before biochemistry gave us the language to describe them precisely.
Naturally lean frame, quick metabolism, variable energy, lighter bone structure. Tends toward anxiety, dry skin, and irregular digestion. Physiologically runs at low baseline insulin — highly sensitive to metabolic disruption even at modest levels.
Athletic medium frame, strong digestion, steady energy, driven temperament. Tends toward inflammation, intensity, and liver-related conditions. Metabolic baseline sits in the middle range across all markers.
Solid, well-built frame, slower metabolism, calm steady temperament, strong endurance. Naturally runs at higher baseline insulin and higher lipid levels — most predisposed to classic metabolic syndrome when out of balance.
These are not rigid categories. Most people are a blend with one dominant type. A predominantly Pitta type could be Pitta/Vata or Pitta/Kapha — and this secondary type does have a clear impact on body frame, and therefore on where that person's thresholds sit. A Pitta/Vata person will lean toward the Vata column; a Pitta/Kapha person toward the Kapha column.
Why the Thinner Build Type Is Most Missed
The most important clinical failure of universal thresholds is the systematic under-detection of insulin resistance in lean individuals — what researchers now call the TOFI phenotype: Thin Outside, Fat Inside. These are people who appear lean and whose standard blood tests look broadly normal, but who carry disproportionate visceral fat around their organs and are measurably insulin resistant.
Their HOMA-IR may read 1.6 — well under the standard cutoff of 2.0, so completely ignored. But for a lean Vata-type individual whose healthy baseline sits around 0.8 to 1.0, a reading of 1.6 represents a doubling of their natural insulin load. The body is already under significant metabolic stress.
The same applies to TG/HDL. In thinner-build types, HOMA-IR typically rises first — the TG/HDL ratio may still look normal even when insulin resistance is already established, because leaner bodies produce less excess triglyceride in the early stages. This means HOMA-IR is the more reliable early marker for this type, and a TG/HDL reading that looks acceptable may be masking a problem that HOMA-IR would already reveal.
Blood pressure follows the same pattern. A Vata-type individual typically runs a resting systolic of 95–105 mmHg. A reading of 118 would be classified as "normal" by any NHS or AHA guideline — but for that constitution it may represent a significant and symptomatic elevation that a constitutionally aware practitioner would act on immediately.
The Constitutional Threshold Table
The table below presents proposed clinically reasoned thresholds for each frame type across three key metabolic markers. These are not derived from a single published study — no such study exists. They are built from the directional evidence in the research below, from known physiological baseline differences between lean and heavier-built individuals, and from the Ayurvedic constitutional framework which has characterised these body-type differences for five millennia.
A practical note on the two main markers: for any given blood sample, the TG/HDL ratio (in mmol/L) will typically be a higher number than the HOMA-IR score. A HOMA-IR of around 2.0 broadly corresponds to a TG/HDL of around 3.0 — at which point insulin resistance is confirmed across all frame types. The thresholds below reflect this relationship. All TG/HDL values are in mmol/L. Blood pressure values are systolic in mmHg.
* Proposed clinical reference points based on constitutional frame type. Interpret alongside symptoms, history, and trends over time — not as standalone diagnostic criteria.
| Marker | Thinner Build (Ayurvedic Vata Type) Lean · light frame · quick metabolism | Medium Build (Ayurvedic Pitta Type) Athletic · driven · strong digestion | Larger / Heavier Build (Ayurvedic Kapha Type) Solid frame · steady · slower metabolism |
|---|---|---|---|
| HOMA-IRFasting glucose × fasting insulin ÷ 405 |
< 1.0 Optimal
1.2 – 1.4 Early concern > 1.5 Likely IR |
< 1.3 Optimal
1.3 – 1.6 Early concern > 1.7 Likely IR |
< 1.6 Optimal
1.6 – 1.8 Early concern > 1.9 Likely IR |
| TG/HDL RatioTriglycerides ÷ HDL cholesterol (mmol/L) Above 3.0 = confirmed IR for all types |
< 1.5 Optimal
1.5 – 2.0 Early concern > 2.0 Likely IR |
< 1.8 Optimal
1.9 – 2.5 Early concern > 2.5 Likely IR |
< 2.0 Optimal
2.1 – 2.8 Early concern > 2.8 Likely IR |
| Systolic Blood PressuremmHg · resting |
95 – 105 Normal
106 – 110 Elevated for type > 110 High for type |
105 – 120 Normal
121 – 125 Elevated > 125 High |
120 – 130 Normal
131 – 140 Elevated > 140 High |
| Disease tendencyConstitutional pattern when IR develops | Anxiety · fatigue · poor sleep · brain fog · irregular digestion · neurological symptoms. In thinner-build types, HOMA-IR typically rises first — the TG/HDL ratio may still look normal even when insulin resistance is already established, because leaner bodies produce less excess triglyceride in the early stages. | Inflammation · elevated liver enzymes (ALT/GGT) · skin conditions · acid reflux · gout. Liver and inflammatory pathway most affected first. | Weight gain · hypertension · high TG · low HDL · fatty liver · cardiovascular risk. Classic metabolic syndrome picture. |
These figures are indications only. One reason for this is that a predominantly Pitta type could be Pitta/Vata or Pitta/Kapha, or very rarely just Pitta. Where there is a secondary type — as is usually the case — this clearly does have an impact on body frame, and the thresholds should be read accordingly. A Pitta/Vata person will sit closer to the Vata column; a Pitta/Kapha person closer to the Kapha column.
Supporting Research
What This Means in Practice
Conventional medicine does not currently measure insulin resistance as a routine test. The HOMA-IR calculation requires a fasting insulin level — a test that is almost never ordered in standard care in the UK, US, or Europe. Most people will need to request this test specifically, or access it through a private or functional medicine practitioner.
A thinner-build individual with a HOMA-IR of 1.6 and a TG/HDL of 2.0 will be told — on the rare occasion it is tested at all — that their results are completely normal. By constitutional frame type assessment, they are likely already insulin resistant and heading toward the conditions most typical of their type: anxiety, fatigue, poor sleep, and brain fog — none of which will be connected to insulin resistance by their doctor.
A larger-build individual with a HOMA-IR of 1.9 is in early concern territory for their type — worth acting on now, through dietary change and intermittent fasting, before the full metabolic syndrome picture develops.
When insulin resistance is identified at whatever level is concerning for your frame type, the intervention is the same across all three types: remove the foods that drive insulin highest — refined carbohydrates, grains, and sugars — introduce structured intermittent fasting, and monitor progress through retesting. The commitment and urgency required is equal regardless of frame type.
The goal is not to alarm people with higher numbers than they expected. It is to give leaner types the early warning they are currently denied, and to give larger-framed types a realistic baseline — so they can monitor meaningful change and reverse insulin resistance while reversal is still straightforward.