Body mass index (BMI) and percent fat mass. A BMI > 27.5 kg/m(2) could be indicative of obesity in the Spanish population

BACKGROUND: The World Health Organization (WHO) defines obesity as a condit ion of excessive fat accumulation to the extent that health and well-being are affected. For population studies, the measurement of weight, corrected for height, is still the method of choice (BMI). In Caucasian populations, the BMI cut-off point for obesity (30 kg/m(2)) corresponds with a percent b ody fat (PFM) of over 25% in young adult males and 35% in young adult femal es. However, the relation between BMI and PFM is not uniform among populati ons. It is important to define in each population the threshold of BMI whic h corresponds to the definition of obesity. PATIENTS AND METHOD: BMI was calculated in 282 subjects. PFM was analyzed u sing Bio-electrical impedance. Blood pressure serum glucose and insulin, an d the fasting insulin resistance index were also determined in all subjects to analyze the metabolic impact. RESULTS: The PFM of 25% in males and 35% in females coresponded to a BMI of 27.5 and 27.4 kg/m(2), respectively. The slope of the relationship between the degree of obesity and co-morbilities (insulinemia, fasting insulin res istance index and blood pressure) was strenghtened above 26 kg/m(2) in men and 24 kg/m(2) in women. CONCLUSIONS: BMI that corresponds to a PFM previously defined as obesity is lower in our population in comparison with other Caucasian populations. Ou r results confirm that is impossible to compare the prevalence of obesity a mong populations using exclusively the BMI. It will be important to define, using reference methods, whether these findings have physiological impact or not, and if this cut-off of BMI determines an increment in cardiovascula r and overall mortality using epidemiological approaches.