Styku Anthropometric Metrics — BMI, WHR, WHtR, and TLVR Explained

Alongside body composition, Styku reports four standard anthropometric and ratio metrics that assess size, proportions, and fat distribution. These metrics help identify chronic disease risk based on where and how fat is carried. All four display a red, yellow, or green health tag in the scan report and Studio.

Body Mass Index (BMI)

BMI measures weight relative to height. It does not distinguish between muscle and fat — a client with high muscle mass and low fat may still show a higher BMI. For a fuller picture, BMI should be considered alongside body composition analysis and waist circumference.

BMI Risk Categories (WHO & NIH)

BMI | Category | Risk Level

< 18.5 | Underweight | Moderate Risk

18.5–24.9 | Healthy | No Risk

25–29.9 | Overweight | Moderate Risk

30–34.9 | Obese Class I | High Risk

35–39.9 | Obese Class II | Very High Risk

≥ 40 | Obese Class III | Extremely High Risk

References

NHLBI Obesity Education Initiative. (2000). The practical guide: identification, evaluation, and treatment of overweight and obesity in adults. NIH/NHLBI.
World Health Organization. (2011). Waist circumference and waist-hip ratio: report of a WHO expert consultation.

Waist-to-Hip Ratio (WHR)

WHR is the ratio of waist (abdominal) circumference to hip circumference. It reflects fat distribution on the body. A higher WHR is an indirect measure of visceral fat — fat that accumulates around organs in the stomach region — which is associated with inflammation, hormonal imbalances, and chronic disease risk.

WHR Risk Categories (WHO)

Males:

WHR | Risk Level

< 0.95 | Low Risk

0.95–1.0 | Moderate Risk

> 1.0 | High Risk

Females:

WHR | Risk Level

< 0.80 | Low Risk

0.80–0.85 | Moderate Risk

> 0.85 | High Risk

References

De Koning, L. et al. (2007). Waist circumference and waist-to-hip ratio as predictors of cardiovascular events. European Heart Journal, 28(7), 850–856.
Grundy, S. M. et al. (2005). Diagnosis and management of the metabolic syndrome. Circulation, 112(17), 2735–2752.
Vazquez, G. et al. (2007). Comparison of BMI, waist circumference, and waist/hip ratio in predicting incident diabetes. Epidemiologic Reviews, 29(1), 115–128.
World Health Organization. (2011). Waist circumference and waist-hip ratio: report of a WHO expert consultation.

Waist-to-Height Ratio (WHtR)

WHtR is waist circumference divided by height. It reflects fat distribution relative to stature — a shorter person with greater abdominal obesity will have a higher WHtR. Useful rule of thumb: keep waist circumference less than half of height. As WHtR increases, chronic disease risk increases.

WHtR Risk Categories

WHtR | Risk Level

< 0.5 | Low Risk

0.5–0.6 | Moderate Risk

> 0.6 | High Risk

References

Ashwell, M., & Gibson, S. (2016). Waist-to-height ratio as an indicator of 'early health risk'. BMJ Open, 6(3), e010159.
Ashwell, M., Gunn, P., & Gibson, S. (2012). Waist-to-height ratio is a better screening tool than waist circumference and BMI. Obesity Reviews, 13(3), 275–286.
Ashwell, M., Mayhew, L., Richardson, J., & Rickayzen, B. (2014). Waist-to-height ratio is more predictive of years of life lost than BMI. PLoS One, 9(9), e103483.
Schneider, H. J. et al. (2011). Measuring abdominal obesity: effects of height on cardiometabolic risk. Diabetes Care, 34(1), e7–e7.

Trunk-Leg Volume Ratio (TLVR)

TLVR is the ratio between torso volume and the volume of the legs, measured using Styku's 3D body scan — a metric that only a 3D-imaging system can produce. Published research has shown that TLVR, as measured with Styku, can predict cardiometabolic blood markers including:

High triglycerides
Low HDL (good cholesterol)
High glucose (blood sugar)
High HOMA-IR (insulin resistance)

TLVR Risk Categories

TLVR | Risk Level

< 1.34 | Low Risk

1.34–1.65 | Elevated Risk

> 1.66 | High Risk

How to Use These Metrics Together

BMI + body fat percentage: BMI alone misclassifies muscular clients. Always pair with body composition.
WHR + WHtR: Both assess fat distribution, but WHtR is often a stronger predictor of disease risk than BMI alone. Use them together for a richer picture.
TLVR: A Styku-unique 3D-shape risk indicator. Best used alongside the other three to flag clients with elevated cardiometabolic risk even when traditional metrics look fine.

All four ratios use the same green/yellow/red tagging scheme used elsewhere in the Styku scan report, making it easy to identify which metric is driving overall risk.

Applies to: All Styku configurations.

Related Resources

What does Styku measure, and what data do clients receive after a scan?
What is waist shape and why does it matter for health risk assessment?
What is anthropometrics?
What is the difference between anthropometric and body composition measurements?
Why should practitioners collect both anthropometric and body composition data?