Waist-to-height ratio: A more accurate way to assess body fat and mortality risk than BMI

A recent study carried out by Cass Business School at London’s City University claims to have identified a more precise way of measuring an individual’s mortality risk other than using the Body Mass Index (BMI) formula.

WHtR CalculatorResearchers involved with the study have found that men and women who carry extra weight around their waist have a significantly shorter life expectancy than others.

By utilising two decades of medical research on over 300,000 adults, scientists have revealed that in order to live a long and healthy life, individuals must have a waistline circumference that is no greater than half their height.1

Indeed, it has been established that individuals who have a waist-to-height ratio (WHtR) of 80 per cent or more could be decreasing their life expectancy by as much as 20 years.2,3

The risk of experiencing health complications such as heart disease, strokes and diabetes is increased in individuals who carry extra weight around their waist.4,5

Research illustrates that it is more about where fat is located in the body rather than how fat an individual is.

Although much of one’s waist fat may be hidden from sight, it accumulates around organs which then creates hormones and substances that have a detrimental effect on cholesterol, blood pressure and blood sugar levels.7,8,9

Previously, BMI has been used as the principal mathematical formula to predict one’s likelihood of obesity and ill health. This formula divides an individual’s weight in kilograms by the square of their height in metres in order to calculate whether they fall into the category of underweight, healthy weight, overweight or obese.10

However, the BMI formula is now being questioned with claims it is inaccurate as this measurement is unable to distinguish between muscle and fat.11,12

This means that elite athletes who have unusual proportions of muscle to fat, such as professional boxers, rowers and gymnasts are often classified as overweight or obese.13,14

Although BMI is a good representation for total body fat, it cannot differentiate between the different types of fat distribution, therefore it is not an appropriate measurement for everyone.15,16

The new WHtR formula is calculated by measuring the circumference of the waist, which is located precisely between the bottom rib and the hip bone (across the belly button).17

This measurement should be taken after letting your breath out and not while taking a breath in.18

The theory is that individuals should live to the average life expectancy (currently the combined male and female figure in Australia is 82.0 years)19 if their waist measurement is half their height or less.20

Scientists are claiming that this new formula could predict the years of life an individual may lose through obesity and the same rules apply irrespective of gender, ethnicity or age.21,22

For example, a 30 year old Australian female who is 164 centimetres tall (5ft 4.5 inches) should have a waist measurement of no more than 82 centimetres. If her waist measurement expands to 60 per cent of her height (98.4 centimetres) she risks losing 1.4 years off her life expectancy. This formula also applies to men, however their rates are higher, with 1.7 years being cut from their life expectancy.23,24

Although these numbers may not appear to be substantial they quickly add up for an individual who is severely overweight or obese. A male who is 30 years old, 177.8 cm tall (5ft 10inches) and has a waist measurement of 142 centimetres risks losing up to 20.2 years from his life expectancy. Likewise a female who is 164 centimetres tall (5ft 4.5 inches) with a waist measurement of 129.5 centimetres can expect to lose 10.6 years from her life expectancy.25,26,27

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Dr Margaret Ashwell, a nutritional expert involved with the aforementioned study has stated that measuring one’s waist circumference is extremely important as it demonstrates how much central fat they are carrying in their body.28,29

This type of fat is closely associated with diabetes, heart disease and high cholesterol. For this reason, she believes that this WHtR is a far more consistent measurement of obesity, ill health and mortality risk than the widely used BMI method.30

A number of health professional believe that implementation of WHtR as a standard screening procedure could greatly reduce years of productive life lost. Furthermore, the test can be easily self-implemented, meaning it can and should be used in the home as a simple health check.31


  1. Sophie Borland, “Forget the fancy gadgets and health apps: for a long life your waistline should be half your height,” Daily Mail Australia, September 7, 2014, (accessed October 8, 2014).
  2. Margaret Ashwell, Les Mayhew, Jon Richarson & Ben Richayzen, “Waist-to-height ratio is more predictive of years of life lost than body mass index,” PLoS ONE 9, no.9 (2014): 1-11.
  3. Anna Roberts, “Key to a long life is a waist measuring less than half your height,” The Telegraph, September 7, 2014,, (accessed October 8, 2014).
  4. Jeanie Lerche Davis, “The risk of belly fat,” Web MD, June 30, 2007,, (accessed October 9, 2014).
  5. BBC News, Many ignorant on ‘waist fat’ risk, (accessed October 16, 2014).
  6. Kimberly Gillan, “Waist to height ratio more accurate health predictor than BMI: academic,” Ninemsn, May 15, 2013,, (accessed October 10, 2014).
  7. Roberts, Key to a long life.
  8. Gillan, Waist to height ratio.
  9. Fiona Macrae, “A pear-shape figure can add 10 years to your life (but the news isn’t so good if you’re shaped like an apple)”, Daily Mail Australia, May 14, 2013,, (accessed October 10, 2014).
  10. Heart Foundation, your BMI,, (accessed October 16, 2014).
  11. Tammy McKenzie, “How flawed and outdated is the body mass index (BMI) measurement?,”, June 18, 2012,, (accessed October 10, 2014).
  12. Jane E. Brody, “Weight index doesn’t tell the whole truth,” The New York Times, August 30, 2010,, (accessed October 16, 2014).
  13. Wesley Stephenson, “BMI: does the body mass index need fixing?,” BBC, January 29, 2013,, (accessed October 10, 2014).
  14. Cass Business School City University London, The secret to a longer life- keep your waist to half your height,, (accessed October 16, 2014).
  15. Margaret Ashwell, “Body Mass Index – BMI – ‘misses obesity risks’,” BBC, Febuary 25, 2011,, (accessed October 10, 2014).
  16. Brody, Weight index doesn’t tell the whole truth.
  17. Gillan, Waist to height ratio.
  18. Borland, Forget the fancy gadgets.
  19. Australian Bureau of Statistics [ABS]. (2013). Deaths, Australia, 2012: Australians living longer (No. 3302.0). Retrieved from
  20. Gillan, Waist to height ratio.
  21. Borland, Forget the fancy gadgets.
  22. Ashwell et al., Waist-to-height ratio.
  23. Roberts, Key to a long life.
  24. Cass Business School, The secret to a longer life.
  25. Borland, Forget the fancy gadgets.
  26. Cass Business School, The secret to a longer life.
  27. Ashwell et al., Waist-to-height ratio, p. 6.
  28. Borland, Forget the fancy gadgets.
  29. Ashwell et al., Waist-to-height ratio.
  30. Nick Collins, “Waist to height ratio ‘more accurate than BMI’,” The Telegraph, May 14, 2013,, (accessed October 10, 2014).
  31. Macrae, A pear-shape figure.


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