The association between Planetary Health Diet, body mass index and polygenic risk score for obesity

BACKGROUND: The way we eat and produce food are threatening our health and environmental sustainability. The EAT-Lancet Planetary Health Diet (PHD) was launched to consider both aspects. The association between PHD and body mass index (BMI) has barely been studied, and especially the role of inheritance in this context is unclear. Therefore, we examined the association between PHD and BMI and further evaluated whether the association differs by the level of genetic susceptibility for obesity. METHODS: In total, 4377 participants (≥18 years, female 56%) from the Finnish FinHealth 2017 Study were included. A validated food frequency questionnaire was used to assess the habitual diet. We developed an energy-standardized dietary index based on the PHD adapted for the Finnish food culture (score range 0 − 13 points). Genetic susceptibility for obesity was evaluated with a polygenic risk score (PRS) based on one million obesity associated single nucleotide polymorphisms. Linear regression was used for the statistical analyses. RESULTS: The mean PHD score for all participants was 4,0 (SD 1,5). There was a borderline negative association between PHD and BMI (β -0.01 95% CI -0.02, 0.00). When the genetic background was considered, this negative association reached statistical significancy in two lowest quartiles of PRS (lower susceptibility for obesity) (p < 0.05). Whereas no association was observed among those with higher PRS for obesity. CONCLUSIONS: Although, the adherence to PHD was relatively, our findings suggested that individuals with lower genetic susceptibility for obesity may benefit from the better adherence to a healthy and sustainable diet in terms of weight maintenance. KEY MESSAGES: • Genetic susceptibility for obesity may play a role in the association between diet and obesity. • Healthy and environmentally friendly diet may be beneficial for weight maintenance even with the low adherence to the diet.