This group will receive individual guidance via the mobile application (12 weeks)

This group will receive a group-based lifestyle intervention program at a Healthy Lifestyle Centre (12 weeks)

This group will receive a group-based lifestyle intervention program at a Healthy Lifestyle Centre plus the mobile application (12 weeks)

Individual lifestyle intervention via an mobile application

We want to assess the proportion of participants willing and able to take part in the study after referral from general practitioner in two different regions in East Norway. Information will be recorded continuously after telephone contact.

We will assess the randomization procedure and asses time spent on the first consultation with the participants. Throughout the study period, the supervisor will log all time spent monitoring participants and giving individual feedback through the app.

The use of the app will be registered in terms of actual use and if patients answered tasks within a week, all based on data shown in the administrator interface. Data on adherence to provided tasks and problems experienced with the mobile app will be retrieved from the app-database. We will also assess whether there are any problems with data management involved in the study and assess whether the study personnel had any challenges in conduct of the study.

User satisfaction with the application will be assessed with the System Usability Scale. (SUS), a paper questionnaire at the end of the intervention.The SUS is a technology independent, 10-item questionnaire with a score between 0 and 100 were 0 represents low usability and 100 represent high usability. We will also asses the experienced usefulness of the app after 12 weeks. This will be measured through a questionnaire designed for this study consisting of 16 questions; 13 questions with answers on a Likert scale (0 to 100), 3 multiple-choice questions, and 1 open-ended question.

These outcomes will be determined by evaluating whether changes in quality of life and physical activity over a 12-week period could be observed and whether these outcomes disclose ceiling or floor effects. To assess these domains, we will use part of standard questionnaires being used in Healthy Life Centers at the beginning and ending of a 12-week intervention period, being the COOP/WONCA (the Dartmount COOP/World Organization of Family Doctors functional health assessment). This is a questionnaire assessing changes in quality of life.It consists of six questions across six domains with a score of 1 in each domain representing the best possible score while a score of 5 is the worst possible score. Physical activity will be assessed with the validated International Physical Activity Questionnaire (IPAQ) short form. It consists of eight items and encompasses questions regarding time spent walking, in moderate and vigorous intensity physical activity, besides sitting time.

Weight and waist circumference will be measured at baseline and at the end of the intervention period.