People should ensure their waist size is less than half their height to help keep health problems at bay, an NHS watchdog has warned.
The National Institute for Health and Care Excellence (Nice) says adults with a body mass index (BMI) under 35 should measure their waist-to-height ratio to check if they fall within a ‘healthy’ range.
The advice comes as part of wider plans to tackle obesity and improve the nation’s health.
It comes after the government introduced calorie counts on food menus across England this week, with cafes, restaurants and takeaways now required to display the calorie information of non-prepacked food and soft drinks for customers.
What is a healthy height-to-weight ratio?
A BMI of 18 to 25 is considered a healthy weight, 25 to 30 is overweight, and over 30 is classed as obese.
By using a waist-to-height ratio, together with BMI, Nice said that people can work out if they are carrying excess fat around their middle, which is known to increase the risk of type 2 diabetes, high blood pressure, stroke, heart disease and certain types of cancer.
For example, a female who is 5ft 4in and has a waist circumference of 29in is considered to have a healthy ratio, but a 32in waist would push them into the unhealthy range.
A man who is 5ft 10in would be at increased health risks with a 36in waist.
Guidelines say a healthy waist to height ratio is 0.4 to 0.49, indicating no increased health risks.
A ratio between 0.5 and 0.59 would put people at a higher risk of health issues, while a ratio of 0.6 or more puts them at the highest risk of health problems.
In line with international guidance, the guideline recommends using lower BMI thresholds for overweight and obesity for people from south Asian, Chinese, other Asian, Middle Eastern, black African, or African-Caribbean backgrounds.
This is because these groups are more prone to carrying weight around their middle and have higher health risks at lower BMIs.
Nice also sets out ways to assess childhood obesity and says tailored plans should be considered for children with a high BMI or a waist-to-height ratio above 0.5.
It should also be noted that BMI cannot tell the difference between excess fat, muscle or bone, and does not take into account age, gender or muscle mass.
Dr Paul Chrisp of Nice said: “Our updated draft guideline offers people a simple and effective way of measuring their weight so they can understand the factors that could impact on their health and take action to address them.
“Our committee found that a clear benefit of using the waist-to-height ratio is that people can easily measure it themselves, interpret the results, and seek medical advice if they are at increased health risk.”
The 2019 Health Survey for England estimated that 28% of adults were obese and 36% were overweight.
The current cost of obesity in the UK is £6.1 billion to the NHS and £27 billion to wider society.
Guideline committee member Professor Rachel Batterham, consultant in obesity, diabetes and endocrinology, added: “Increased fat in the abdomen increases a person’s risk of developing several life-limiting diseases including type 2 diabetes and heart disease.
“Waist-to-height ratio is a simple, easy-to-use measure that identifies people who are at increased health risk and would benefit from weight management support to improve their health.”
The draft guidance is subject to consultation.
How do I calculate my waist-to-height ratio?
Anyone wishing to find out their waist to height ratio can use an online calculator or could ask a health professional to work it out for them.
The NHS has an online tool to check your BMI and information on taking your waist measurement.
Regardless of your height or BMI, it is recommended that people should try to lose weight if their waist measurement is:
- 94cm (37ins) or more for men- 80cm (31.5ins) or more for women
People are considered to be at very high risk and should contact a GP if their waist size is:
- 102cm (40ins) or more for men- 88cm (34ins) or more for women