Feasibility and acceptability of the intervention
We screened around 2,000 people and only 105 people were eligible. The relatively low eligibility rate (5.25%) indicates that extensive screening may be needed in a future study. It is difficult to compare the eligibility rate in this study with those of previous interventional studies because the eligibility rate varied greatly among the different studies. For example, the eligibility rate in some studies could reach 62.36% [The findings of the semi-structured interview revealed both positive and negative aspects of the intervention process. On the one hand, the participants recognised the positive role of the BCTs in encouraging them to modify their dietary habits from unhealthy to healthy. The continuous support from the interventionist during the intervention process was reported as being a crucial factor in bringing about changes in behaviour. Previous studies on lifestyle modifications tended to focus on the provision of knowledge, materials, and professional education, which may be insufficient for making behavioural changes [Contextual cultural factors may pose some barriers to changing dietary behaviour, as reflected by the relatively low rate of adherence to keeping a food diary. According to our qualitative interviews, the barriers included internal factors (e.g., previous eating habits) and external factors (e.g., specific aspects of Chinese dining culture). For example, Chinese families are used to eating together and sharing dishes, which may cause difficulties for participants in controlling the amount of food that they eat compared to individual servings. In addition, some participants were busy taking care of their grandchildren, so they hardly had adequate time to keep a detailed food diary. These external barriers need to be addressed in future research by including family members in the study, to increase the awareness of family members and relieve some of the burden on the participants.