What is the waist-to-hip ratio?

Written by Dr Katie Stephens, GP

Dr Katie graduated from the University of Manchester in 2007 (MBChB) and completed her GP training in the West Midlands in 2012 (MRCGP). 

 

This is a simple measurement of the circumference of the waist, divided by the circumference of the hips. It is a useful way of showing if someone has a healthy amount of body fat around their middle in proportion to their hips. We know that carrying too much fat, especially when that fat is on the tummy, increases the risk of a number of diseases and conditions, such as Diabetes, Heart Disease and Fatty Liver Disease.  

The other measurements that tell us if there is too much tummy fat are waist-to-height ratio and waist circumference.  

What is the waist-to-height ratio?

This is another useful tool that has recently been recommended by the National Institute of Health and Clinical Excellence (NICE). The ratio is calculated by dividing the waist measurement by the height, ensuring use of consistent units ie both in cm, or both in inches.  

For example, if your waist is 76cm, and your height is 165 cm, your waist-to-height ratio will be 76 ÷ 165 = 0.46. (See ‘how to measure your waist circumference’ below for instructions.) 

In 2022 NICE published a recommendation that adults with a BMI of less than 35 should assess their waist-to-height ratio and aim for their waist to be less than half of their height (this would give a ratio of 0.5 or less)1.  

One of the advantages of the waist-to-height ratio is that, as most people know their height already, they only need to measure one new thing, which can easily be done at home. Remembering to keep the waist as less than half of the height is also fairly simple, and there is no need to refer to a detailed guide to know if your number is healthy or not. 

What is the waist circumference?

This is simply just the measurement of your circumference at the level of your waist. The reading isn’t used in any sort of calculation or ratio to another body measurement, it is just given on its own. 

Advantages over the BMI

While these waist measurements and ratios are generally seen as a helpful additions to, rather than a replacements of, the traditionally-used BMI (Body Mass Index), there are some instances where they are particularly helpful: 

• Muscular builds. People who have a lot of muscle in their body may fall in an ‘overweight’ or even ‘obese’ category when their BMI is calculated. This is because the only two factors that the BMI looks at are weight and height. It does not differentiate between weight due to muscle and weight due to fat. For muscular people, it can therefore be hard to assess the amount of fat using BMI alone. Because we know that it is the extra fat that is important when looking at someone’s risk of various diseases, the BMI is less helpful here. However, any of the waist measurements (waist-to-hip ratio, waist-to-height ratio, or waist circumference) do take into account how much fat there is, making them the more useful tools here. 
• Certain ethnicities. First, a quick reminder: tThe reason we assess whether someone’s weight is healthy or not is because being overweight is linked with a number of diseases, including Diabetes and Cardiovascular Disease. People with a South Asian, Chinese, other Asian, Middle Eastern, Black African, or African-Caribbean ethnicity are known to be at increased risk of these diseases at LOWER BMI’s than Caucasians1. The current BMI Categories can therefore underestimate their risk, giving false reassurance that they have a healthy weight. (NICE recommends classifying ‘overweight’ as a BMI of 23 – 27.4, and ‘obese’ as 27.5 or higher for people with the above ethnicities1, compared to cut offs of 25 and 30 for Caucasians). Unfortunately, this is not something that is widely known and so adding in a waist-to-hip or waist-to-height ratio (or even just a simple waist circumference on its own) is more likely to give an accurate idea of what the risk is for people with these family backgrounds. 

People with a South Asian, Chinese, other Asian, Middle Eastern, Black African, or African-Caribbean ethnicity are also known to have a greater risk of carrying too much fat around the tummy. With tummy fat in particular being the key factor leading to many health problems, it is especially important to know if your amount of tummy fat is safe or not if you have one of these backgrounds. This is best done with one of the measurements that includes the waist.  

• Young People. BMIs tend to be less useful in children and young people, due to the physical differences in a young body versus an adult body. For this reason, often height and weight centile charts are used. However, according to Dr Nivedita Aswani (Consultant Paediatrician and NICE guideline committee member), having a waist circumference of more than half of the height is an indicator of greater risk in children and young people also2. 

• Healthy BMIs. A ‘healthy BMI’ for Caucasians is 18.5 – 24.9. For people of Black, Asian, and certain other minority groups (as described above) it is 18.5 – 22.9.  However, it is possible to fall in this ‘healthy’ range but still have too much tummy fat. This might happen if you don’t have a great deal of muscle on you. Using one of the waist measurements here can help identify people who may not have otherwise realised they are at increased risk of developing problems. 

How do I calculate my waist-to-hip ratio?

General pointers

Ideally, the measurements should be taken while you are stood straight, with your shoulders back. It is best to do this in a private room, where you can remove any clothing around your midsection that could affect your readings. The measuring tape should sit snug against the skin, without being so tight that it pinches. It should also lie parallel to the floor (in a straight, level line across your body, rather than looking higher on one side than the other). For extra accuracy, repeat each measurement a second or even third time, and take an average. 

How to measure your waist circumference

Your waist is roughly halfway between the bottom of your rib cage and your hip bones. This is usually just above the belly button, but may not be, depending on your shape. Wrap the measuring tape around your body here. It is important not to suck your tummy in as this can affect your reading. Take a deep breath in, breath all the way out, let your tummy muscles relax, and then take your reading. There is a useful YouTube video instructional video from Diabetes UK here. 

How to measure your hip circumference

First, stand with your legs together. Then, wrap the measuring tape around the body below your hips, and around your bum. Your hip measurement is actually the reading at your widest point here, so you may need to move the tape up and down the body to find it. Generally, this is somewhere between the top of the thigh bone and the lower part of the bum5. (‘Hip circumference’ is a somewhat misleading name, as your widest point may be a fair distance from your actual hip bones.) 

How to calculate your waist-to-hip ratio

Once you have the above readings, make sure they are both in the same unit e.g., both in cm, or both in inches – it doesn’t matter which you use, as long as it is the same for both. Then, and then simply divide the waist number by the hip number to get your waist-to-hip ratio. For example, if your waist circumference is 30 inches, and your hip circumference is 38 inches, your waist-to-hip ratio is 30 ÷ 38 = 0.79. 

Cut-offs

Once you have calculated your waist-to-hip ratio, waist-to-height ratio or just your waist circumference, the next question of course is, is this healthy? Here are some handy references for you to use to see where your ratio lies. 

Waist-to-hip ratio references

Currently, NICE doesn’t have any specific guidelines that we can refer to here. Because of this, the cut-offs you see online may vary depending where you look. The World Health Organisation has published a 39 page document about the waist-to-hip ratio. But even this does not recommend a specific cut-off. It does, however, say that its previous definition of obesity as a ratio of ≥ 0.9 for men and ≥ 0.85 for women (which is often quoted by others) was ‘just an example’ and not a formal recommendation6. 

However, the International Diabetes Federation does also use these same figures as cut-offs7, which gives us a bit more confidence using them, although this may need to be interpreted with caution as the supporting evidence is from a sample of some 5000 people in the Netherlands, and may not represent other ethnicities well. 

Waist-to-height ratio categories

NICE advises that the following references can be used for people with a BMI under 35 kg/m2 of both sexes and all ethnicities, including adults with high muscle mass1: 

Waist-to-height ratio	Level of tummy fat (central adiposity)	Health risks (Including risk of Type 2 Diabetes, Hypertension and Cardiovascular Disease)
0.4 to 0.49	Healthy	No increase
0.5 to 0.59	Increased	Increased
0.6 or more	High	Further increased

 

Waist circumference

Here is a reference for looking at purely just the waist circumference. These cut offs apply no matter your what your height, hip circumference or BMI are. 

GENDER (ADULTS)	LOW RISK	HIGH RISK	VERY HIGH RISK
White European, Black African, Middle Eastern and mixed origin
MEN	< 94 cm (37 inch)	94–102 cm (37-40 inch)	> 102 cm (40 inch)
WOMEN	< 80 cm (31.5 inch)	80–88 cm (31.5-34.6 inch)	> 88 cm (34.6 inch)
African Caribbean, South Asian, Chinese and Japanese origin
MEN	< 90 cm (35.4 inch)		> 90 cm (35.4 inch)
WOMEN	< 80 cm (31.5 inch)		> 80 cm (31.5 inch)

Table source: https://elht.nhs.uk/services/dietetics/body-measuring-techniques 

What to do if my waist-to-hip ratio is raised?

If you find out that you are in one of the higher risk groups from any of the above measurements (waist-to-hip, waist-to-height, or just waist circumference), this means that there is more chance of you suffering from Diabetes, Strokes, Heart Attacks and other serious conditions. However, the good news is that knowing about it now can make a difference – if you lose weight, you may be able to prevent these things from happening. 

Even if you have already been diagnosed, losing weight can still be helpful and can improve how well-controlled your condition is. For instance, with Type 2 Diabetes, weight loss can help the body start functioning more normally again – for more information on type 1 diabetes and type 2 diabetes please check out our definitive guides. In some cases, this can even lead to the Diabetes completely resolving8,9. Weight loss can also help improve blood pressure10 and cholesterol levels, and help with symptoms of other conditions too, such as Obstructive Sleep Apnoea. 

If you fall in any of the very high risk categories, please speak to your NHS GP or practice nurse for advice and support on healthy options for losing weight.  

For more information on ways to eat healthier and move more, visit NHS Change4Life11. For advice on how your GP may be able to help with weight loss, please click here12. 

References

1. https://www.nice.org.uk/guidance/cg189/chapter/Recommendations 
2. https://www.nice.org.uk/news/article/keep-the-size-of-your-waist-to-less-than-half-of-your-height-updated-nice-draft-guideline-recommends 
3. https://elht.nhs.uk/services/dietetics/body-measuring-techniques 
4. https://www.youtube.com/watch?v=e4cUSNq_OY8 
5. https://www.uhs.nhs.uk/Media/Southampton-Clinical-Research/Procedures/BRCProcedures/Procedure-for-adult-circumference-measurements.pdf 
6. http://apps.who.int/iris/bitstream/handle/10665/44583/9789241501491_eng.pdf;jsessionid=7D1DB1C32C3EACFA85DF9A328D00ACBC?sequence=1 
7. Alberti, K. G., Zimmet, P., & Shaw, J. (2006). Metabolic syndrome–a new world-wide definition. A Consensus Statement from the International Diabetes Federation. Diabetic medicine : a journal of the British Diabetic Association, 23(5), 469–480. https://doi.org/10.1111/j.1464-5491.2006.01858.x 
8. Taheri, S., Zaghloul, H., Chagoury, O., Elhadad, S., Ahmed, S. H., El Khatib, N., Amona, R. A., El Nahas, K., Suleiman, N., Alnaama, A., Al-Hamaq, A., Charlson, M., Wells, M. T., Al-Abdulla, S., & Abou-Samra, A. B. (2020). Effect of intensive lifestyle intervention on bodyweight and glycaemia in early type 2 diabetes (DIADEM-I): an open-label, parallel-group, randomised controlled trial. The lancet. Diabetes & endocrinology, 8(6), 477–489. https://doi.org/10.1016/S2213-8587(20)30117-0  
9. Lemieux I. (2020). Reversing Type 2 Diabetes: The Time for Lifestyle Medicine Has Come!. Nutrients, 12(7), 1974. https://doi.org/10.3390/nu12071974 
10. https://www.kinetikwellbeing.com/definitive-guide-blood-pressure/ 
11. https://www.nhs.uk/healthier-families/ 
12. https://www.nhs.uk/live-well/healthy-weight/managing-your-weight/how-your-gp-can-help-you-lose-weight/