Procedure
Subjects were randomly assigned to the intervention (n = 65) and the control (CON, n = 35) group (2:1 ratio) because the intervention group consisted of those who could have “risk” or “no-risk” genotypes of genes in genetic testing results. Randomization was conducted using a random sequence generated with PROC SURVEYSELECT in SAS version 9.4 (SAS Institute, Cary, NC, USA). The random sequence was concealed until the baseline survey was completed. The intervention group was further subclassified into an intervention-low risk (ILR, n = 32) and an intervention-high risk (IHR, n = 33) group, based on the polygenic risk score calculated for each gene item by assigning 1 point for “borderline risk” and 2 points for “caution”. The subjects in the ILR and the IHR group were informed about their genetic test results regarding the risks for a high BMI and abnormal lipid profiles, such as elevated TG and cholesterol concentrations, at the beginning of the intervention, whereas those in the CON group were not informed about their test results until the end of the study. No further treatment was provided. While the researcher, which is the outcome assessor, was blinded to the group assignment information by using randomly assigned IDs for all subjects used in both online and document-type questionnaires, all the study subjects were exposed to the random assignment results.