MyLifestyleCoach: main study

Regular and sufficient physical activity (PA) and healthy nutrition are related to a decreased risk for a variety of diseases, such as CVD, Diabetes II, osteoporosis, cancer, and depression. Almost half of the Dutch population is insufficiently active, with the lowest PA levels found among low socioeconomic status groups and most adults do not meet the healthy nutrition guidelines. The small effect sizes and limited sustainability of effects that are usually found for existing PA and diet interventions stress that strong, innovative interventions are urgently needed to improve PA and dietary intake patterns of the Dutch adult population. Web-based computer-tailored interventions are a promising approach to improve PA in the population at a relatively low cost. Most web-based computer-tailored interventions are based on theoretical constructs from traditional health behaviour theories. Autonomous motivation, an important construct in SDT and MI, plays a major role in the promotion and maintenance of PA in the long run. However, MI is an intensive, costly counselling technique, able to reach only limited numbers of people. This makes MI inapt for promoting PA and diet among the large Dutch population. Computer tailoring can be a suitable technique to combine individual counselling with a large scale reach. Previous research has shown that MI principles can successfully be translated into written CT (Friederichs et al., 2015, 2016). Therefore, it is possible that web-based computer-tailored interventions based on SDT and MI are more effective to promote diet and PA than interventions based on traditional health behaviour theories. We investigate the effect of a web-based computer tailored intervention based on principles from the SDT and MI compared to a waiting list control condition on diet (intake of fruit, vegetables, fish, and snacks) and physical activity after 6 and 12 months after baseline.

It is hypothesised that compared to waiting list control condition, participants in the intervention improve their diet and physical activity on the short (6 months after baseline) and long-term (12 months after baseline; when the participant chooses to follow that particular module).

Baseline

Follow up 1 at 6 months

Follow up 2 at 12 months

After giving informed consent, participants are automatically assigned to either the intervention condition or the waiting list control condition by means of a digital randomizer which is built-in in the website.



Participants who are enrolled in the intervention condition start with the program MyLifestyleCoach after the baseline questionnaire (T0).
MyLifestyleCoach is a web-based computer-tailored diet and physical activity (PA) intervention, based on Self-Determination Theory (SDT) and motivational interviewing (MI). The program begins with a questionnaire and is followed by an opening session. In the opening session the program is explained in detail by a video coach and by text. Furthermore, participants receive information about the Dutch nutrition and PA guidelines and about their own current nutrition/PA behaviour. Participants are then free to choose whether they would like to follow the diet module (I Eat) and/or physical activity module (I Move) or none of them. Both modules consist of 4 online sessions over a period of 3 months that help them to think about their importance of improving their diet/increasing their physical activity and motivate them to choose their behaviour.

Several aspects of diet/PA are discussed throughout the session. Participants receive information about the Dutch nutrition/PA guidelines and about their own current diet/PA behaviour. They are able to request additional information about the effects of regular physical activity/nutrition in several domains such as physical health, mental health, and physical appearance. The importance of a healthier diet/regular PA is discussed through elaborating on the relationship between the participant’s personal held values and a healthier diet/regular physical activity, and by exploring the possible effects on the short and on the long term of a healthier diet/regular physical activity. Furthermore, attention is paid to the participant’s confidence (that he/she could succeed in eating more healthily/becoming more physically active) by looking at personal strengths and positive experiences and by elaborating on tips and tricks. Finally, participants can formulate their own specific action plan. They also can make their own coping plans. In the first sessions, more emphasis is placed on eliciting change talk and increase self-determined motivation, while the latter sessions focus more on self-regulation aspects.



Participants who are enrolled in the waiting list control condition receive no intervention. However, they can start with “MyLifestyleCoach” after the RCT has ended, i.e. after the 12-month questionnaire.