Determining Body Composition-Based BMI Cut-Offs for Ethiopian Adults in Northwest Ethiopia: A Population-Based...

Body mass index (BMI) is widely used as a population-level measure of obesity, given its robustness and inclusion in health surveys. However, for Ethiopians, the applicability of universally recognized anthropometric cutoffs may be inadequate. This study aimed to determine body composition-based BMI cutoffs for the healthy adult population of Ethiopia.

A population-based cross-sectional study was conducted in the Amhara region of Ethiopia from June to August 2023, collecting anthropometric data and body fat percentage from 838 adult participants. The body fat percentage was measured using the Omron Body Composition Monitor and Scale, which utilizes the bioelectrical impedance analysis (BIA) method to estimate various body measurements. Data were analyzed using Stata and MedCalc software. BMI cutoff values were determined using the receiver operating characteristics (ROC) analysis, and performance was assessed using area under the curve (AUC), Youden index, sensitivity, and specificity.

The optimal BMI cutoff values for defining obesity were 24.8 kg/m² for young adult men and 23.2 kg/m² for young adult women. For mature adult men and women, the values were 25.4 kg/m² and 26.3 kg/m², respectively. These cutoff values showed the highest effectiveness in defining obesity. The optimal BMI cutoff values for underweight, normal weight, and overweight categories were: ≤ 18.0 kg/m², 18.1-20.5 kg/m², and 20.6-24.8 kg/m² for young adult men; ≤ 18.3 kg/m², 18.4-21.1 kg/m², and 21.2-23.2 kg/m² for young adult women; ≤ 16.5 kg/m², 16.6-20.8 kg/m², and 20.9-25.4 kg/m² for mature adult men; and ≤ 17.1 kg/m², 17.2-21.1 kg/m², and 21.2-26.3 kg/m² for mature adult women. The proposed BMI cutoffs performed well in identifying underweight and overweight individuals.

The identified BMI cutoff values for Ethiopians were lower than international standards. Adopting these country-specific cutoffs would be more appropriate for clinical practice and research in Ethiopia.