Body mass index in 17-year-old Israeli males of different ethnic backgrounds; national or ethnic-specific references?

OBJECTIVE: To evaluate whether a single national reference is appropriate for assessing prevalence of overweight in heterogeneous populations, or whether ethnic-specific references are needed. DESIGN: A population-based study of Israeli Jewish males who underwent routine physical and clinical examinations prior to army recruitment served as the basis for the development of two types of references for body mass index (BMI): a national reference (NR) and an ethnic-specific reference (ER). SUBJECTS: Consecutive cohorts of all 17-y-old Jewish male recruits (n=109, 570). MEASUREMENTS: Weight, height and blood pressure values were obtained. BMI was calculated, and the 85th percentile of BMI was used as a cut-off point for overweight, using both types of references. Prevalence of hypertension among recruits was used as a biomarker to support the reliability of the ER when discrepancy in classification between the two references was found. RESULTS: As compared to the NR, three ethnic groups had a BMI distribution shifted to the left (light sub-population) and five were shifted to the right (heavy sub-population). In the light sub-population, 7% of the inductees who were classified as having normal weight by the NR were considered overweight by the ER and had a hypertension rate similar to that of those defined as overweight by both references (3.1 per 1000). In the heavy sub-population the 4% of subjects who were overweight by NR and normal by ER had hypertension rates similar to those defined as normal weight by both references (2.7/1000), and significantly lower than that of those classified as overweight by both references (10.8/1000). CONCLUSION: In heterogeneous populations, ethnic references should be used to evaluate prevalence of overweight, rather than one national reference. International Journal of Obesity (2000)24, 88-92

Relationship between morbidity and extreme values of body mass index in adolescents.

BACKGROUND: Although the association between overweight and cardiovascular risk factors is well documented in cross-sectional and longitudinal studies, reports of adolescent morbidity associated with underweight in industrialized countries are rare. METHODS: This population-based study includes approximately 110,000 17 year old Israeli Jewish males who underwent routine physical examination at army induction centres. Computerized data tapes include overall health profiles, specification of physical and mental conditions, and height and weight measurements. Medically significant conditions are those with sufficient severity to preclude service in a combat unit. RESULTS: Functional limitation is more prevalent at both extremes of the body mass index (BMI) distribution: 149.5/1000 among severely underweight individuals and 164.3/1000 among severely overweight subjects. Overweight was associated with hypertension (14.9/1000 among the severely overweight), as well as joint conditions of the lower extremities, mainly hip, ankle and knee disorders. Functional disorders associated with underweight are bronchial and lung conditions, including asthma (14.2 and 18.9/1000 in the mildly and severely underweight), scoliosis, intestinal conditions and emotional disorders (mainly neurosis). CONCLUSIONS: Both under- and overweight are associated with morbidity at age 17. Intervention programmes should begin at an early age.