Obesity module 1: management in primary care

Opportunities to take these measurements include registration with a general practice, consultation for related conditions (such as type 2 diabetes and cardiovascular disease) and other routine health checks.

The following tips should ensure you can accurately measure and record height and weight, determine body mass index and accurately measure waist circumference.

Remember many people will be nervous about being measured and/or weighed. They may have had bad experiences of being weighed previously and some patients report that they avoid seeking advice about other medical problems because they feel so anxious about being weighed.

Height, weight and BMI

Click here for useful instructional videos on measuring patient height and weight

Make sure your surgery is equipped for treating people who are severely obese with, for example, special seating and adequate weighing and monitoring equipment.³ Create a positive environment to improve patients’ sense of acceptance. Ensure measurements are not hurried to ensure they are accurate as possible.

Before taking weight measurements, a person should remove their shoes, items in pockets and heavy clothing such as coats, belts and so on.  Always measure weight without commenting on it in a private area.

When recording height, again make sure the person has removed shoes, caps and taken down any hairstyle or headwear on top of their head. Ensure their heels, hips, shoulders and head are flat against the wall. Ask them to take a deep breath and bring down measurement slide and record height. For certain groups of patients, such as those wearing turbans, those who cannot stand straight or steadily, or those who are wheelchair bound, height cannot be measured. It may be better to assess obesity using waist circumference measurements instead.

Once height and weight has been measured, BMI can be calculated using the following formula:

Weight (kg)

Height² (m)

A useful patient resource for calculating BMI, provided by the BHF, can be found at http://www.bhf.org.uk/bmi/BMI_Calc.html

Waist circumference

This is a good measure of ‘central obesity’ but does not help to assess people with a BMI > 35 kg/m². Only one measurement is required per individual, and the cost of the equipment (a tape measure) is negligible.²⁵ Figure 6 shows how to measure waist circumference.²⁶

• Measure midway between the uppermost border of the iliac crest and the lower border of the costal margin
• Ensure you have a tape of adequate length available.
• Place tape around the abdomen at the level of this midway point, and take reading when the tape is snug but does not compress the skin (In may be difficult to accurately palpate those bony landmarks in very overweight patients in which case placing the tape at the level of the belly button is recommended²⁴
• The least intrusive method for measuring waist circumference, which avoids bodily contact, is to ask the patient to hold the tape measure at the correct point and turn around 360 degrees.