In a recent article about why Waist Circumference and Waist-to-Height Ratio is so important, I explained that a meta-analysis from 2012 which pooled data from 300,000 adults of different races and ages found that the lowest risk of cardiovascular disease and shorter lifespan was associated with a Waist to Height Ratio (WHtR) of 0.5. That is, we are at lowest risk when our waist circumference is less than half our height (even if our BMI is in the normal range). I also explained exactly how to take waist circumference, so that the results are accurate.
There are other measures of cardiovascular risk that I think are worth considering.
- A 2015 study of 3200 adults found that Waist-to-Hip Ratio (WHR) is more accurate in predicting 10-year cardiovascular risk than Waist to Height Ratio (WHtR), however whether this relationship would hold up in a sample as large as the meta-analysis above is unknown. I feel it is worth mentioning Waist-to-Hip Ratio (WHR) as an indicator of cardiovascular risk, as it is easy to do.
- Another index this 2015 study found to accurately predict 10-year cardiovascular risk was something called Conicity Index which I will touch on even though it is not as easily determined as Waist-to-Hip Ratio (WHR) or Waist to Height Ratio (WHtR).
Determining Waist to Hip Ratio
As mentioned in the previous article, to use these indices requires waist measurements and hip measurements to be done accurately and at a specific place on the body. To make it easier, I will repeat how to measure waist circumference here and below, how to measure hip circumference.
Measuring Waist Circumference
For the purposes of calculating risk associated with increase abdominal girth, waist circumference needs to be measured at the location that is at the midpoint (i.e. half way) between the lowest rib and the top of the hip bone (called the “iliac crest”). Below is a picture that should help.
This measurement should be taken with a flexible seamstress-type tape measure, being sure that the tape measure is at the same height in the front and the back, when looking in front of a mirror. That is, the tape measure should be perpendicular to the floor (not higher in the back or the front).
It’s also important that the person’s abdomen (belly) is completely relaxed when taking the measurement, not sucked in. One way to do that is to taking a deep breath and let it out fully just as the measurement is taken.
If your Waist to Height ratio is greater than 0.5, then you are at increased risk for cardiovascular events and a shortened lifespan. Looking at the graph above, one can see that for every little bit over 0.5, the risk rises steeply.
Measuring Hip Circumference
Hip circumference needs to be measured at the widest portion of the buttocks (butt) and as with waist circumference, the tape measure needs to be parallel to the flood (same height in the front and the back, when looking in front of a mirror).
For both the waist and hip measurement, the tape measure should be snug around the body, but not pulled so tight that it is constricting and it is best if a stretch‐resistant but flexible seamstress-type tape measure is used.
Assessing Waist-to-Hip Ratio
If the waist circumference is measured in inches, then the hip circumference needs to be as well – same if the measurement is in centimeters; both need to be in the same units.
To calculate the Waist-to-Hip Ratio take the waist circumference and divide it by the hip circumference.
Waist-to-Hip Ratio and Risk of Cardiovascular Disease
The following ratios are associated with low, moderate and high risk of cardiovascular risk;
Low Risk: For men, if the ratio is 0.95 or less, for women if the ratio is 0.80 or less
Moderate Risk: For men, if the ratio is 0.96 – 1.0, for women if the ratio is 0.81 – 0.85
High Risk: For men, if the ratio is 1.0 or more, for women if the ratio is 0.85 or more.
The Waist-to-Hip Ratio can also be thought of as people being shaped like “apples” or “pears“.
People who carry most of their excess weight around their middle (“apples”) have more visceral fat and this type of fat is much more dangerous than the fat under our skin (called “sub-cutaneous fat”) because it is found around the heart, liver, pancreas and other organs and increases the risk not only of cardiovascular disease, but also Type 2 Diabetes and hypertension.
People who’s hips are much wider than their waist (so-called “pears”) have less visceral fat and therefore lower risk of these weight-related health problems.
Conicity Index(CI) is a little more cumbersome a calculation than either Waist-to-Hip (WHR) Ratio or Waist-to-Height (WHtR), but was found in the 2015 study mentioned above with 3200 subjects to be a strong predictor of cardiovascular risk.
Conicity literally means “cone-shaped” and determines how much our body fat distribution like two end-to-end cones.
In the first figure below, body weight is distributed evenly, however when someone has a conical distribution, their weight is more heavily distributed around the abdomen. As a result, it has increased conicity and is more highly correlated to increased cardiovascular disease (as well as Type 2 Diabetes and hypertension).
For those who are interested in calculating Conicity Index (CI), the formula is below along with the formula for Waist-to-Hip (WHR) Ratio, Waist-to-Height (WHtR).
Given the sample size of the data on which Waist-to-Height (WHtR) is based (300,000 adults) and that it is an easy to determine and robust measure of cardiovascular risk, this is the one I tend to favour. That said, Waist-to-Hip (WHR) Ratio was previously used for years and found to be a simple and accurate predictor of risk. From that point of view, either could be used, but why not both?
In my clinical experience, I have encountered many people with much wider hips than waist (so-called “pears”) but whose Waist-to-Height (WHtR) is considerably greater than 0.5, and for this reason I tend to put more credence on Waist-to-Height (WHtR) than Waist-to-Hip (WHR) Ratio as a measure of visceral fat and increased cardiovascular risk.
Since both Waist-to-Height (WHtR) and Waist-to-Hip (WHR) Ratio are very easy to determine, for those with a family risk of cardiovascular disease, Type 2 Diabetes or hypertension, I think it makes sense to aim for a waist measurement that is within both of these easily obtained measures.
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- Rabiee B, Motamed N, & Perumal D, et al. Conicity index and waist-hip ratio are superior obesity indices in predicting 10-year cardiovascular risk among men and women. Clin. Cardiol. 38, 9, 527–534 (2015)
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