A randomised controlled trial to determine the effect of genotype-based personalised diet and physical activity advice for FTO genotype (rs9939609) delivered via email on healthy eating motivation in young adults.

The prevalence of obesity continues to rise, and public health dietary recommendations are not being adhered to. The transition to higher education is a period of risk for weight gain in young adults and has been demonstrated as a good time to initiate behaviour change. A genotype-based personalised approach to dietary recommendations may motivate young adults to maintain or adopt positive dietary behaviours. The aim of the present study was to determine the efficacy of genotype-based personalised dietary and physical activity advice on healthy eating motivation in young adults. Participants were young adults (n = 153), aged 18-25 years. Baseline measures (participant characteristics, height, weight, body mass index [BMI], body fat percentage [BF%], healthy eating motivation and physical activity) were collected. Participants were genotyped for a SNP in the FTO gene (rs99396090) and randomly allocated (stratified for genotype) to three different groups (1. Genotype-based personalised advice: dietary and physical activity advice based on genotype, BMI and reported physical activity; 2. Non-genotype-based personalised advice: dietary and physical activity advice based on BMI and reported physical activity; 3. Control: no advice). A week after receipt of advice delivered via email, participants completed the healthy eating motivation questionnaire for a second time. Genotype-based personalised dietary advice did not affect healthy eating motivation: when participants were analysed across the whole group (p = 0.417), when analysed according to those informed of a risk or non-risk-associated genotype (p = 0.287), or when analysed according to those with a BMI (>25 kg/m²; p = 0.336) or BF% (male >18%, female >31%; p = 0.387) outside the healthy range. There was also no significant difference in healthy eating motivation at 1-week in the control or non-genotype-based advice groups. Genotype-based personalised advice for the prevention of obesity did not affect healthy eating motivation in this group of healthy, young adults.