Body mass as a result of psychological, lifestyle and genetic determinants. A pilot study involving overweight/obese and normal weight women in their early adulthood.

Aim: The causes of obesity and overweight are complex and depend on mutually interrelated groups of lifestyle, psychological and genetic factors. Among 46 identified point mutations known within FTO gene, mutation SNP rs9939609 has the strongest effect on an increase in body weight. Therefore, the study aimed to assess psychological, lifestyle and genetic factors (expressed by the frequency of the FTO SNP rs-9939609 gene variant) and their association with body weight in young adult women.

Methods: We genotyped FTO rs9939609 SNP in cheek swabs collected from 49 women aged 18-35, equally with and without overweight and obesity. Eating behaviour was defined based on the Questionnaire of Eating-Related Behaviors (QERB) and physical activity by the International Physical Activity Questionnaire (IPAQ). Classical anthropometric indices and the body composition analysis results measured by bioelectrical impedance were used to characterise nutritional status.

Results: Overweight/obese participants had significantly higher body composition parameters than normal-weight participants, along with lower physical activity levels and more time spent sitting. Overweight/obese women presented significantly higher scores in emotional overeating, habitual overeating, and dietary restrictions, indicating more problematic eating behaviors compared to normal-weight individuals. No significant differences were observed in BMI, lifestyle factors, or eating behaviors across FTO gene variants (AA, AT, and TT). However, the TT and AT FTO gene variant groups showed significant positive correlations between habitual overeating and key measures of body weight (BMI, WC, and FM). In contrast, the AA variant group exhibited fewer associations between psychological and lifestyle factors with body weight.

Conclusions: Psychological and lifestyle factors, particularly overeating behaviors, were more strongly associated with increased body weight in women with the TT and AT variants of the FTO SNP rs-9939609 gene, highlighting the potential influence of genetic predisposition on eating habits and weight status in this population. Proper eating habits and high physical activity play an important role in preventing overweight and obesity regardless of the genotype that poses a potential risk of weight gain. The study's findings bring practical implications for health education and health psychology.