Table 1.

Text message examples used to represent the content of text messages used in the intervention and typical adolescent responses from focus groups.

Category	Text message	Key strategies	Examples of adolescent responsesa
Healthy eating	After dinner can be a good time to eat some fruit. If you had less than 2 bits of fruit today, you might like some tinned apricots & yoghurt for dessert?	Message including a ‘helpful tip’	I liked it except I didn’t have any of that stuff. [Adolescent 10 (A10)] I’d prefer if you told me to have strawberries. [A12]
			It’s ok but I don’t really eat after dinner. [A4]
Sedentary behavior	A CAFAP teen has found using an egg-timer is a good way of knowing it’s time for an active break after playing on the computer for 30 mins. You could choose to try it too.	Testimonial message	Most probably wouldn’t influence my behavior because, I don’t know, I get addicted to my computer. [A3]
Physical activity	What are the reasons you want to be more active? You might like to think about these when the going gets tough!	Intrinsic motivation, reflecting goal-setting process used during the program	It makes you actually think about it. You have it there but you don’t actually think about it. [A7]
Physical activity	How many steps have you done today? How about trying to do a few extra thousand steps this afternoon?	Reflective questioning	There’s nothing wrong with it, but like saying a few extra thousand like is too much. [A5] It would make you think about doing more steps. [A1]
Goal setting	Have a look at your goals for physical activity, sedentary behavior and healthy eating. Plan something fun to do this weekend to help meet your goals.	Bigger picture, reinforcing key CAFAP areas and goal setting.	I have homework on the weekend, like every day… If I’m not doing homework I’m sleeping. Like pretty much. [A11]
Healthy eating	How many bits of junk food have u had today? You could challenge yourself to see if you can go the rest of the day without any junk food. Some cut up fruit might be a sweet treat instead!	Reflective questioning and ‘helpful tip’	I felt really guilty because I think I’d had ummm I’d had something, maybe a donut for breakfast. [A2]

^aAdolescents were assigned a code to distinguish between responders. The code ranges from A1-A12.