Accurately measuring obesity rates across ethnic groups is essential to tackling health inequalities. This analysis explores how updated BMI thresholds and waist-to-height ratio guidance reveal a more accurate picture of obesity prevalence in minoritised communities.
One of Nesta’s missions is to increase the number of healthy life years lived in the UK while narrowing health inequalities. To achieve this, our mission goal is to halve the prevalence of obesity by 2030. Understanding the true scale of the challenge is key to effectively reducing obesity and improving the nation’s health. Body mass index (BMI) is widely used to assess health risks related to body weight and estimate obesity prevalence. National statistics have so far relied on the same BMI criteria to assess obesity in all ethnic groups. But this one-size-fits-all measure fails to account for the higher risk of weight-related health conditions faced by individuals from Black, Asian, and other minoritised ethnic groups at equivalent BMI levels compared to individuals from white backgrounds.
Recognising this, the National Institute for Health and Care Excellence (NICE) revised its BMI guidelines in 2023 and again in 2025 to recommend lower BMI thresholds for overweight and obesity for adults from South Asian, Chinese, other Asian (Japanese, Korean and Thai), Middle Eastern (Arab and Iranian), Black African or African-Caribbean backgrounds. NICE also recommended considering a waist-to-height ratio measurement for some individuals, which better captures variation in body composition and its impact on the risk of weight-related disease.
This analysis explores the impact of these updated guidelines on the prevalence of overweight and obesity in minoritised ethnic groups and on the population as a whole. All data referenced is for adults in England.
Key findings
Reassessing the prevalence of excess weight (overweight and obesity) for adults in England using the updated BMI thresholds and waist-to-height ratio guidance, we find:
- A rise from 60% to 76% in rates of excess weight (overweight and obesity) among adults from Black, Asian, and other minoritised ethnic groups. Excess weight prevalence among adults from white ethnic groups is 65%.
- This represents an absolute increase of: 13 percentage points (pp) in Black ethnic groups, 18 pp in Asian ethnic groups and 12 pp in Arab ethnic groups.
- A rise from 64% to 67% in rates of excess weight across all adults.
Adult population living with overweight and obesity by ethnicity
Image Description
Bar chart titled 'Adult population living with overweight and obesity by ethnicity – Comparing different BMI thresholds'. The chart compares the percentage of the adult population living with overweight and obesity based on BMI thresholds that are either adjusted or not adjusted for ethnicity.
- Total Population: The BMI-adjusted bar (blue) is longer than the non-adjusted bar (light grey), indicating a higher percentage when adjusted.
- White: The blue and grey bars are almost the same length, showing little difference between the two thresholds.
- Black: The blue bar is noticeably longer than the grey bar, indicating a higher obesity rate when BMI is adjusted.
- Asian: The blue bar is significantly longer than the grey bar, showing a substantial increase in the population classified as overweight or obese when BMI is adjusted.
- Arab: The blue bar is also longer than the grey bar, reflecting a higher obesity rate with adjusted BMI.
X-axis: Percentage of the adult population (0% to 100%).
Legend: Blue represents BMI adjusted for ethnicity, grey represents BMI not adjusted for ethnicity.
- The updated BMI thresholds are more aligned with the assessment of health risk using the waist-to-height ratio for adults from Black, Asian and some other minoritised ethnic groups, providing a more accurate reflection of health risks and body composition compared to previous BMI thresholds.
- Our main analysis excludes adults from mixed and other minoritised ethnic backgrounds due to insufficient evidence for their inclusion.
Recommendations
These results highlight a significant underestimation of obesity rates within many minoritised ethnic groups using old BMI thresholds.
Nesta recommends that the revised NICE BMI thresholds are integrated into NHS and government national statistics, like the Health Survey for England, to more accurately measure obesity rates among different ethnic groups and at a population level, as well as to better understand and act on health inequalities between different groups.
