Should we be shunning the scales in favour of a tape measure? Evergreen Life looks at why your waist measurement might be a better indicator than your weight.
We know that obese people are at risk of poorer health outcomes. It seems like a simple connection. But actually weight and fat are not as tightly related as you might think. In fact, stepping on the scales to measure your weight can be misleading as a way of predicting health problems. The body mass index (BMI) is a measure that uses your height and weight to work out if your weight is healthy. But it may not always give you the full picture. Your body fat percentage or waist measurement can be more reliable indicators or predictors of potential health problems.
It might be more helpful to ditch the terms ‘overweight/underweight’ for ‘overfat/underfat.’ In 2017, an estimated 70% of the world had become overfat – with that figure rising to over 90% in countries like the USA and Greece. In the UK nearly 87% of men are overfat, with around 77% of woman in the same bracket. But what does that mean? Overfat describes a body fat level that can actually hurt your health. For men, a healthy body fat percentage lies between 8-19%; for women 21-33% is ideal.
Let’s take a look at why weight and BMI are potentially misleading, and how to get a more accurate picture of your health using the simple tape measure.
You must speak to your GP about any unintentional increase or decrease in your weight. This may be a sign of significant illness.
Weighing up the scales
Evergreen Life’s Wellbeing Survey reported that body weight scales were by far the most common method of measuring health and wellbeing. That’s probably because it’s become like a morning ritual for us – the scales looming in the corner of the bathroom ready for us to step onto before we start our day.
But weight scales don’t know whether you’re a muscular athlete or a growing teenager. And that’s a key issue.
What if you’re exercising to lose weight? The scales don’t consider that you might experience a healthy amount of muscle development and that extra muscle has to weigh something! This can be more than a bit disheartening to see you’ve gained weight after working hard at the gym.
The problem with BMI
How about BMI – or Body Mass Index? It’s at least taking into consideration your height…
For people with a with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family background the cut offs are:
| Healthy weight | BMI 18.5 kg/m2 to 22.9 kg/m2 |
| Overweight | BMI 23 kg/m2 to 27.4 kg/m2 |
| Obesity | BMI 27.5 kg/m2 to 37.4 kg/m2 |
| Severely obese | BMI 37.5 kg/m2 or above |
For people whose family background isn’t listed above:
| Healthy weight | BMI 18.5 kg/m2 to 24.9 kg/m2 |
| Overweight | BMI 25 kg/m2 to 29.9 kg/m2 |
| Obesity | BMI 30 kg/m2 to 39.9 kg/m2 |
| Severely obese | BMI 40 kg/m2 or above |
It’s quick and doctors can easily evaluate a patient’s risk of heart disease, diabetes and other illnesses like cancer and osteoarthritis. But, there are some instances which can lead to a deceptive BMI result.
BMI doesn’t really measure body fat. You might be a healthy weight according to your height, but you can still carry too much body fat and even classify as obese. This means you could be likely to experience some of the same medical risks in people who are more obviously overweight. Dr Brian Fisher, GP in South East London and Strategy and Clinical Director at Evergreen Life, highlights that “measuring your waist circumference seems to give you a better idea of your risk of heart disease than measuring your BMI.”
Also, BMI doesn’t determine the location of fat in your body. You might have a high BMI, but the fat is stored in your hips. Another person with a similar BMI might have a lot of belly fat – or visceral fat – which causes many dangerous health conditions including certain cancers. For instance, a 2024 study found increases in belly fat, indicated by waist measurements, were more strongly associated increased risk of colorectal cancer than BMI.
So interpreting it sometimes needs caution. BMI may not be helpful if you are:
Pregnant.
Muscular, as BMI may not show accurate fat levels.
Over 65, due to other health conditions, and possible protective effect of having a slightly higher BMI when older.
Measuring your body fat
To take an accurate measurement of your body fat, you’d need a costly scan. You could also consider buying bio-impedance scales that send electrical pulses through your body to “read” how much body fat you have.
The US Navy have also developed a way to estimate body fat too, using age, gender, height, and neck measurements. There are a few calculators online.
One simple ways to estimate body fat is to simply measure your waist circumference and you can store it in the Evergreen Life app.
How to measure your waist
- Grab a tape measure!
- Locate the bottom of your ribs and the top of your hips.
- Wrap the tape measure around your waist midway between these points (this will be just above your belly button).
- Breathe out naturally before taking the measurement, then check the number on the tape measure.
- Store your waist measurement in the records section of the Evergreen Life app so you keep track.
Don’t worry about doing this every day! Do what works for you, but once per month is a good idea. Set a reminder in your phone to measure it at the same time every month so it’s most accurate.
So, what is a healthy waist measurement?
Put simply, you should probably try to lose weight if you’re a man with a waist more than 94cm (37 inches) or a woman with a waist of more 80cm (31.5 inches).
Current NHS guidance suggests you may at very high risk of some serious health conditions and should see a GP if your waist is more than 102cm (40in) or more for men or 88cm (34.5in) or more for women.
But you’ll get a more specific range if you compare your waist against another measurement:
Waist-to-height ratio
Be sure to measure your waist circumference and height in the same units. Divide your waist measurement by your height measurement. For instance:
35 inches divided by 64 inches = waist-to-height ratio of 0.55.
Results:
The National Institute for Clinical Excellence (NICE) generate national guidelines for the UK medical community. The table below shows what NICE regards as a healthy waist-to-height ratio:
| Healthy levels of fat around the waist | Waist-to-height ratio 0.4 to 0.49, indicating no increased health risks |
| Increased fat around the waist | Waist-to-height ratio 0.5 to 0.59, indicating increased health risks. |
| High levels of fat around the waist | Waist-to-height ratio 0.6 or more, indicating further increased health risks. |
These classifications can be used for adults with a BMI under 35 kg/m2 of both sexes and all ethnicities, including adults with high muscle mass.
NICE encourages adults with a BMI under 35 kg/m2 to keep their waist measurement to less than half their height, to reduce their risk of potential type 2 diabetes, hypertension (high blood pressure) or cardiovascular (heart) disease. So, aim for a waist-to-height ratio of under 0.5.
Waist-to-hip ratio
Your waist hip ratio can also shed light on body fat and the Evergreen Life app can help you with this too.
Go to records>personal records>measurements and find the waist:hip section. Add your waist and hip measurements here and the app will to the rest. If you don’t have the app, just divide your waist by your hip measurement (in the same units):
- For men = above 1 is too high. Aim for below 0.95 to reduce risk of disease.
- For women = over 0.85 is too high. Below 0.8 puts you at a lower risk of disease.
If you’re worried about your waist measurement, it’s worth thinking about your diet and exercise regime. There are links to Evergreen articles below that you might find helpful.
Keep an eye out for your notification to take the BMI and Body Fat Check in the Evergreen Life app to help you maintain or work towards a healthy measurement.
Keep track
Interested in monitoring your body measurements? You can track changes with the Evergreen Life app. Its personal health and fitness monitor lets you record various results including waist, body fat, BMI and blood pressure, so you can understand your fat loss progress and maintain your general wellbeing. You can also receive more personalised tips on how to improve other aspects of your wellbeing, such as diet, sleep and mental health. By recording what you’re doing and how it effects you in the app, you’ll also will help us get a greater understanding of what works and what doesn’t. Who knows what you may help us learn?
Reviewed by:
Dr James Harmsworth King MBBS MPhil PhD Biotechnology & Medical Expert
Is BMI an accurate way to measure body fat?
Waist circumference as a vital sign: Consensus Statement on Visceral Obesity
Why is my waist size important?
Evergreen Life | What’s in a healthy diet
Evergreen Life | 5 key areas to improve your fitness
Recommendations | Obesity: identification, assessment and management | Guidance | NICE
