What BMI qualifies for bariatric surgery?

Under the 2022 ASMBS and IFSO guidelines, metabolic and bariatric surgery is recommended at a BMI of 35 or more regardless of other conditions, and should be considered at a BMI of 30 to 34.9 with metabolic disease such as type 2 diabetes. NICE recommends referral at a BMI of 40 or more, or 35 to 39.9 with a significant condition that could improve with weight loss, with thresholds 2.5 lower for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean family background.

Are BMI thresholds lower for Arab and Asian patients?

Yes. NICE lowers the BMI thresholds by 2.5 for people of Middle Eastern and Asian family background, among others, because they develop diabetes and other obesity-related disease at a lower BMI. The ASMBS and IFSO guidelines suggest offering surgery to Asian patients from a BMI of 27.5.

BMI calculator for bariatric surgery eligibility

Creator: Dr. Mohammed Maree
Published: 2026-11-03
License: https://creativecommons.org/licenses/by-nc/4.0/

Written and clinically reviewed by Dr. Mohammed Maree, consultant minimally invasive and bariatric surgeon, Al-Makassed Hospital, Jerusalem, and Assistant Professor of Surgery, Al-Quds University. Last updated 3 November 2026.

Enter the measurements

Weight (kg)

Height (cm)

About the patient (adults)

South Asian, Chinese, other Asian, Middle Eastern (including Arab), Black African or African-Caribbean family backgroundLowers the thresholdsA significant obesity-related conditionType 2 diabetes, hypertension, sleep apnoea, fatty liver disease, cardiovascular disease, idiopathic intracranial hypertensionType 2 diabetes

BMI classes (WHO)

BMI (kg/m²)	Class
Below 18.5	Underweight
18.5–24.9	Healthy weight
25–29.9	Overweight
30–34.9	Obesity class I
35–39.9	Obesity class II
40 or more	Obesity class III

For Asian populations the WHO suggests action points at a BMI of 23 (increased risk) and 27.5 (high risk), because type 2 diabetes and heart disease appear at lower weights.

Who qualifies for bariatric surgery?

Guideline	Criteria
ASMBS / IFSO 2022	Recommended at BMI 35 or more, with or without other disease. Considered at BMI 30–34.9 with metabolic disease. In Asian patients, offered from BMI 27.5.
NICE	Referral at BMI 40 or more, or 35–39.9 with a significant condition that could improve with weight loss. Expedited assessment for recent-onset type 2 diabetes. All thresholds 2.5 lower for South Asian, Chinese, other Asian, Middle Eastern, Black African and African-Caribbean backgrounds.

A worked example

A 41-year-old Palestinian woman, 98 kg and 160 cm, with type 2 diabetes for three years. BMI = 98 ÷ 1.6² = 38.3, obesity class II. Under NICE her Middle Eastern background lowers the threshold to 32.5 with a significant condition, so she qualifies. Under ASMBS/IFSO 2022 surgery is recommended at any BMI of 35 or more.

BMI is not the whole story

BMI does not separate fat from muscle or show where fat sits. Waist circumference adds the risk of central fat. A BMI threshold opens the door to an assessment; the decision to operate comes from the whole multidisciplinary team, including the dietitian, psychologist, physician and surgeon.

References

Eisenberg D, et al. 2022 ASMBS and IFSO: indications for metabolic and bariatric surgery. Surg Obes Relat Dis 2022;18:1345–56.
NICE. Overweight and obesity management (NG246), 2025, incorporating the 2023 update on referral for bariatric surgery. Summary: BMJ 2023;382:p1880.
WHO Expert Consultation. Appropriate body-mass index for Asian populations. Lancet 2004;363:157–63.

Educational use

This calculator is a teaching aid. It does not replace clinical judgement, senior advice or your local guidelines.

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BMI and bariatric surgery eligibility