How to Track Weight and Measurements Properly Since NICE NG246

If your records hold weight and BMI and nothing else, they no longer support a NICE-aligned assessment. Since NG246 you also need height, waist circumference, and the patient's family background, because the thresholds change depending on it.

That guideline landed on 14 January 2025 and replaced CG189. It is a genuine change to what you should be measuring, and most practice software still models the old picture: a weight field, a BMI calculation, and a graph.

What changed in NG246?

Two recommendations do the work.

Waist-to-height ratio became a required measure for most adults. Recommendation 1.9.14 says that for adults with a BMI under 35, you should use waist-to-height ratio alongside BMI to assess central adiposity.

BMI thresholds became ethnicity-specific. Recommendation 1.9.11 sets lower thresholds for people from several backgrounds, because cardiometabolic risk appears at a lower BMI.

Both of those require data most systems do not capture.

What are the waist-to-height bands?

Waist circumference divided by height, in the same units. The bands from recommendation 1.9.14:

These apply across all sexes and all ethnic groups, which makes the ratio a useful equaliser alongside a BMI figure that does not behave the same way across populations.

The practical rule of thumb patients remember: keep your waist under half your height.

On technique, waist is measured midway between the bottom of the ribs and the top of the hips, with the patient breathing out naturally. Measuring over clothing, or at the navel by habit, produces a number that is not comparable with anybody else's.

Which BMI thresholds apply to whom?

This is the part that changes classification rather than just adding a field.

For people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family backgrounds, recommendation 1.9.11 sets lower thresholds:

A patient with a BMI of 28 is overweight under the general thresholds and in the obesity category under the adjusted ones. Same number, different classification, different conversation.

Which means you cannot classify anyone correctly without recording family background, and that has to be asked for and recorded rather than assumed from a name or an appearance.

What does this mean for your records?

Four fields, where many systems have one.

1. Weight, dated
2. Height, which most systems capture once and then never revisit
3. Waist circumference, dated, with a note of the measurement method
4. Family background, recorded once, as reported by the patient

From those you derive BMI and waist-to-height ratio, and you apply the right threshold set. A system that stores only weight can produce a trend line, but it cannot produce an assessment.

Two practical notes. Height is not static in older adults, so a height recorded in 2019 may be wrong. And waist circumference has more measurement variability than weight, so recording who measured it and how matters if you are going to compare across appointments.

Does this replace MUST?

No, and it is worth being clear that these are different tools for different questions.

MUST, the Malnutrition Universal Screening Tool from BAPEN, screens for undernutrition rather than adiposity. It scores on three components: a BMI band, unplanned weight loss over the previous three to six months, and an acute disease effect.

Its weight-loss scoring uses percentages: a loss of under 5% scores zero, 5 to 10% scores one, and more than 10% scores two. The BMI component scores zero above 20, one between 18.5 and 20, and two below 18.5.

MUST also functions as a valid first step feeding into the GLIM criteria for diagnosing malnutrition, which require one phenotypic and one aetiologic criterion to be met.

So the honest summary is that NG246 governs how you assess overweight and central adiposity, while MUST and GLIM govern the other end of the spectrum. Both need serial measurements, and both need the measurement to be comparable with the last one.

What good tracking actually looks like

Serial, dated, attributable and comparable.

Serial. One measurement is a data point, three are a trajectory. The clinical value is almost entirely in the trend.

Dated. Not "recent", an actual date, because a percentage weight change over three to six months is meaningless without knowing the window.

Attributable. Who measured it. Inter-rater variation on waist circumference is real.

Comparable. Same method, same equipment where possible, recorded consistently. A waist measured over a jumper in December is not comparable to one measured properly in June.

This is where the record-keeping and the clinical work meet. In Atlacare, dietitian and nutritionist notes capture weight, height and waist circumference with BMI calculated automatically, and the patient profile charts weight and BMI over time, so a series is a series rather than a scattering of notes. It does not yet calculate waist-to-height ratio or apply the adjusted thresholds, so those are still yours to work out and record. And no system can decide which thresholds apply to your patient. That remains a clinical judgement informed by information you have to ask for.

Where to start

1. Add waist circumference to your assessment template if it is not there
2. Re-record height for anyone whose figure is more than a couple of years old
3. Ask about family background and record it, because you cannot apply 1.9.11 without it
4. Write down your measurement method so that the next person to measure does it the same way
5. Review NG246 itself rather than a summary, including this one, before changing how you classify anyone

The guideline is the authority here. This article is a prompt to go and read it, and a warning that if your system only holds weight, you have a data problem before you have a clinical one.

This is general information about a clinical guideline, not clinical advice. NICE guidance is updated; check NG246 in its current form before applying any threshold. Recommendation numbers cited are as published at the time of writing.

Sources: NICE NG246, Overweight and obesity management · NG246 full text via NCBI Bookshelf · BAPEN, Malnutrition Universal Screening Tool · GLIM criteria

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