Attenuation of the effect of the FTO rs9939609 polymorphism on total and central body fat by physical activity in adolescents: the HELENA study

OBJECTIVE: To examine whether physical activity attenuates the effect of the FTO rs9939609 polymorphism on body fat estimates in adolescents. DESIGN: Cross-sectional study. SETTING: Athens, Greece; Dortmund, Germany; Ghent, Belgium; Heraklion, Greece; Lille, France; Pécs, Hungary; Rome, Italy; Stockholm, Sweden; Vienna, Austria; and Zaragoza, Spain, from October 2006 to December 2007. PARTICIPANTS: Adolescents from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (n = 752). MAIN EXPOSURE: Physical activity. MAIN OUTCOME MEASURES: The FTO rs9939609 polymorphism was genotyped. Physical activity was assessed by accelerometry. We measured weight, height, waist circumference, and triceps and subscapular skinfolds; body mass index (BMI [calculated as weight in kilograms divided by height in meters squared]) and body fat percentage were calculated. RESULTS: The A allele of the FTO polymorphism was significantly associated with higher BMI (+0.42 per risk allele), higher body fat percentage (+1.03% per risk allele), and higher waist circumference (+0.85 cm per risk allele). We detected significant or borderline gene x physical activity interactions for the studied body fat estimates (for interaction, P = .02, .06, and .10 for BMI, body fat percentage, and waist circumference, respectively). Indeed, the effect of the FTO rs9939609 polymorphism on these body fat parameters was much lower in adolescents who met the daily physical activity recommendations (ie, >/=60 min/d of moderate to vigorous physical activity) compared with those who did not: +0.17 vs +0.65 per risk allele in BMI, respectively; +0.40% vs +1.70% per risk allele in body fat percentage, respectively; and +0.60 vs +1.15 cm per risk allele in waist circumference, respectively. CONCLUSION: Adolescents meeting the daily physical activity recommendations may overcome the effect of the FTO rs9939609 polymorphism on obesity-related traits.