Why does the NHS use lower BMI cut-offs for some ethnic groups?

What are the NICE BMI cut-offs?

For most adults, overweight starts at 25 and obesity at 30; for the groups NICE names, overweight starts at 23 and obesity at 27.5.¹

BMI (body mass index) is your weight in kilograms divided by your height in metres, squared. NICE’s obesity guideline sets these bands:¹

Named groups: South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background. NICE lowers the class 2 and 3 thresholds by 2.5. Source: NICE NG246, recommendations 1.9.10 and 1.9.11.¹

For someone 1.70 m (5 ft 7 in) tall, BMI 30 is about 87 kg (13 st 9 lb). BMI 27.5 is about 79 kg (12 st 7 lb). That gap of about 7 kg (1 st 2 lb) is what the lower line means in practice.

Why does the same BMI mean more risk for some groups?

Because many people in these groups carry more fat around the middle, and their diabetes and heart risk rises at a lower BMI.^1,2

NICE says people in these groups “are prone to central adiposity”, meaning fat around the belly and organs. Their “cardiometabolic risk occurs at lower BMI”.¹

The clearest English evidence is a 2021 study of 1,472,819 adults in GP records. It followed them for a median of 6.5 years.² It asked which BMI gave the same type 2 diabetes risk as a BMI of 30 in White adults:²

So the risk gap varies a lot between groups. NICE still uses one practical figure, 27.5, for all of them.¹

How does ethnicity change NHS rules for weight medicines?

On the NHS, NICE lowers each BMI threshold for Mounjaro and Wegovy by 2.5 for these groups, so 35 becomes 32.5 and 40 becomes 37.5.^3,4

Mounjaro, England. NICE gives the example of 37.5 instead of 40 in the current phases.³ The phase from around June 2026 covers BMI 32.5 to 37.4 with 4 of 5 named conditions for these groups. See Mounjaro on the NHS.

Wegovy, England. NICE’s usual 35 becomes 32.5, and its 30 to 34.9 band becomes 27.5 to 32.4.⁴ Scotland’s SMC says a lower cut-off “may be more appropriate” for minority ethnic groups.⁹

Private prescriptions follow the medicine’s licence. The licence wording for both is a BMI of 30, or 27 with a weight-related condition. No ethnicity adjustment is written in.^5,6

What does waist-to-height ratio add?

It measures belly fat directly: NICE says a ratio of 0.5 to 0.59 means increased health risk, and 0.6 or more means high risk.¹

NICE uses it for adults with a BMI under 35, of both sexes and all ethnicities.¹ It also tells clinicians that someone with a “healthy” BMI may still carry too much central fat.¹

To measure, find the bottom of your ribs and the top of your hips. Measure around your waist midway between them, just above the belly button, after breathing out.¹⁰

Then divide your waist by your height, in the same units. NICE’s example: 96.5 cm ÷ 170 cm = 0.57, or 38 in ÷ 67 in = 0.57.^1,10 Our guide to weight and health explains both measures.

What are the limits of these cut-offs?

They are a practical shortcut, not a diagnosis: one figure covers very different groups, and NICE itself lists open research questions.^2,11

The English study found equivalent points from 23.9 to 28.1 depending on group.² NICE’s single 27.5 line sits between them.¹

NICE asks researchers whether the same thresholds hold for first-, second- and third-generation immigrants.¹¹ We found no NICE guidance on how to apply the thresholds to people of mixed heritage. The study used self-reported ethnicity.²

A threshold is the beginning of a conversation with a clinician, not a verdict. Our guide on whether to consider a GLP‑1 covers the rest of that decision.

Questions people ask

How we researched this

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