The Significance of the FTO Gene for Weight and Body Composition in Swedish Women With Severe Anorexia Nervosa During Intensive Nutrition Therapy

Abstract

Objective: The aim of this prospective study was to investigate the potential influence of the fat mass and obesity-associated gene (FTO), SNP rs9939609, on body mass index (BMI) and body composition in women with anorexia nervosa (AN) undergoing intensive nutrition therapy. Method: Twenty-five female patients with AN (20.1 ± 2.3 years; BMI, 15.5 ± 0.9 kg/m2) were included for 12 weeks of treatment with a high-energy diet. FTO was genotyped and body composition parameters were assessed by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography at baseline and after 12 weeks. Results: The distribution of the different FTO genotypes were as follows: AA, 24%; TA, 48%; and TT, 28%. Patients gained a median of 9.8 kg (range, 5.5–17.0 kg) and BMI increased to 19.0 ± 0.9 kg/m2. The increase in BMI, fat mass, and the quotient fat/muscle area was significant for the TT and TA genotype groups. Total lean mass was stable in all genotype groups. We could not demonstrate any difference among the 3 FTO genotypes related to the increases in BMI during nutrition therapy when the additive, dominant, and recessive models of inheritance were applied. Conclusions: Irrespective of the FTO genotype, there was no difference in weight response during nutrition therapy. Hence, in this small study there was limited support for individualized nutrition therapy for AN based on FTO genotype.