Effect of a digital health behaviour change support system on cardiovascular disease risk in a randomized weight loss trial

) were randomized into three groups: CBT-based group counselling and self-help guidance (SHG) delivered face-to-face, and usual care. These groups were further divided into HBCSS and non-HBCSS groups. The 10-year CVD risks were assessed using the FINRISK calculator. Baseline median overall CVD risks were similar between groups. In two-group analyses comparing HBCSS and non-HBCSS groups, after 12 months, CVD risks decreased in both groups. However, after 24 months, only the HBCSS group maintained significant reductions in overall risk (-0.40%, p < 0.001). Among participants with obesity, the HBCSS group demonstrated a sustained decrease in overall and coronary artery disease risk, while there were no CVD risk reductions in the non-HBCSS group. However, the differences between HBCSS and non-HBCSS groups were not significant in any analyses conducted, and there were no significant differences in six group analyses between intervention groups. The HBCSS group showed significant reductions in weight, BMI, and waist circumference (at 12 and 24 months) and in LDL cholesterol (at 12 months), compared with controls (p < 0.05). The HBCSS results in a decrease in CVD risk factors, which is reflected by a sustained reduction in calculated CVD risks, especially among participants with obesity.