People are being encouraged to take their own waist measurement to identify if they are at risk of potential health problems, in updated draft NICE weight management guidelines.

Under the proposals, waist-to-height ratio will be used alongside BMI to find patients at risk for conditions such as type 2 diabetes, hypertension or cardiovascular disease.

Anyone with a BMI under 35 kg/m², will be encouraged to also take a waist measurement with advice to ‘keep your weight to less than half your height’, before seeking advice from a healthcare professional.

The guidelines committee said several studies noted it can provide a practical estimate of central adiposity and, when used in addition to BMI, predict weight-related conditions.

NICE also now recommends using lower BMI thresholds for overweight and obesity for people from South Asian, Chinese, other Asian, Middle Eastern, Black African, or African-Caribbean families than from other ethnic groups.

BMI should be ‘interpreted with caution’ in those with high muscle mass and people older than 65 years but waist measurement can be used in all adults, the guidelines which are out for consultation state.

Waist-to-height ratio should also be considered in children aged five and older to assess and predict health risks, the guidelines said.

NICE also highlights the importance of healthcare professionals asking permission before any discussions with people that are linked to being overweight, obese or having central adiposity, and to do so in a sensitive and positive manner.

Dr Paul Chrisp, director for centre for guidelines at 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.’

Professor Tom Sanders, professor emeritus of nutrition and dietetics at King’s College London, said as a rule of thumb waist measurement was useful for younger and middle-aged adults but there were limitations in older people.

But he added that this simplistic calculation would likely ‘classify far more older adults being at risk of diabetes than the current International Diabetes Federation guidelines’.

Professor Naveed Sattar, professor of metabolic medicine at the University of Glasgow said keeping your waist less than half your height may be an additional useful message for the public.

‘Whether this new message gets taken up is uncertain but it never harms to try new ways to get people to consider their health status.

‘However, in the end, we need better interventions to help people change behaviour and also a less obesogenic environment to improve the health of the nation.  There is much to do to tackle the UK’s rising waist girths.’

Meanwhile, the NHS diabetes prevention programme has helped some 18,000 patients avoid type 2 diabetes, according to a recent study.

And NHS England has expanded its ‘soups and shakes’ weight loss programme, which targets type 2 diabetes by helping obese patients lose weight.

NICE draft weight management guideline

1.1.2    Encourage adults with a body mass index (BMI) below 35 kg/m² to:

  • measure their own waist-to-height ratio
  • seek further clinical measurements and advice from a healthcare practitioner if the measurement indicates an increased health risk.

1.1.3     Use BMI as a practical measure of overweight and obesity. Interpret it with caution because it is not a direct measure of central adiposity.

1.1.4     In adults whose BMI is below 35 kg/m² measure and use waist-to-height ratio, as well as BMI, as a practical estimate of central adiposity to help to assess and predict health risks (for example, type 2 diabetes, hypertension or cardiovascular disease).

1.1.6     Define the degree of overweight or obesity in adults as follows

  • healthy weight: BMI 18.5 kg/m2 to 24.9 kg/m2
  • overweight: BMI 25 kg/m2 to 29.9 kg/m2
  • obesity class 1: BMI 30 kg/m2 to 34.9 kg/m2
  • obesity class 2: BMI 35 kg/m2 to 39.9 kg/m2
  • obesity class 3: BMI 40 kg/mor more.

Use clinical judgement when interpreting the healthy weight category because a person in this category may nevertheless have central adiposity.

1.1.7     People with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family background are prone to central adiposity and their cardiometabolic risk occurs at lower BMI, so use lower BMI thresholds as a practical measure of overweight and obesity:

When defining obesity classes 2 and 3 for people in these groups, reduce the BMI thresholds in recommendation 1.1.6 by 2.5 kg/m2.

1.1.8     Interpret BMI with caution in adults with high muscle mass because it may be a less accurate measure of central adiposity in this group.

1.1.9     Interpret BMI with caution in people older than 65, taking into account comorbidities, functional capacity and the possible protective effect of adiposity

1.1.10  Define the degree of central adiposity based on waist-to-height ratio as follows:

  • healthy central adiposity: 0.4 to 0.49, indicating no increased health risks
  • increased central adiposity: 0.5 to 0.59, indicating increased health risks
  • high central adiposity: 0.6 or more, indicating further increased health risks.

Higher levels of adiposity are associated with health risks such as type 2 diabetes, hypertension or cardiovascular disease. The boundary value of 0.5 can be easily communicated: ‘Keep your waist to less than half of your height’.

This classification can be used for both sexes and all ethnic groups. It can also be used in highly muscular adults.

Source: NICE