BACKGROUND/OBJECTIVES: Body fatness and heart disease risk factors can differ considerably between ethnities for a given body mass index (BMI). Information is lacking on differences between various Caucasian populations within Europe. The aim was to investigate the differences in anthropometrics and risk factors between adults from Iceland, Spain and Ireland.SUBJECT/METHODS: This was a secondary analysis of the baseline data from the SEAFOODplus YOUNG intervention study, in which 324 subjects (20-40 years, BMI 27.5-32.5 kg/m(2), from Iceland, Spain and Ireland) participated. Fasting glucose, insulin, blood lipids and body compossition were measured, insulin resistance was calculated using the homeostasis model assessment of insulin resistance.RESULTS: Although age and BMI did not differ between Spanish, Irish and Icelandic subjects, Irish subjects had significantly higher waist circumference (3.2 and 6.7 cm) and body fat percentage (4.4 and 2.0%) compared with Icelandic and Spanish participants, respectively. Irish participants had also more unfavorable cardio-metabolic risk factors compared with Spanish and Icelandic subjects. However, correction for waist attenuated the observed differences considerably, in particular for total cholesterol, low-density lipoprotein and triglycerides.CONCLUSIONS: Despite having near identical BMI and age, our results show that study participants from different populations within Europe differ considerably in cardio-metabolic risk factors, partly due to differences in body fat distribution. European Journal of Clinical Nutrition (2013) 67, 254-258; doi:10.1038/ejcn.2013.6; published online 30 January 2013