Table 2.

Description of the Cell Phone app components

App Component	Behavioral strategies	Group	Description
Tutorial	Skill building	CP	3–8 minutes each of orientation and coaching tutorials on various lifestyle change topics related to weight loss.
Live wallpaper (tips, links, facts)	Skill building, visual reminder, Feedback	CP	A short message is presented periodically on the live wallpaper; the messages are related to tips for healthy living, health news relevant to weight loss, jokes or motivational quotes.
Weighing	Self- Monitoring, feedback	CP (with prompting) and PC	A feature to track weight. A historical weight graph is shown after the participant weighs him/herself.
Food tracking (detailed &simple foods)	Self- Monitoring, feedback	CP (with prompting) and PC	A detailed and simplified food tracker with which participants can track everything they eat in a day, or individually track meats, fruits, vegetables, sugar sweetened beverages and participants’ overall impressions of the healthfulness of their meals.
Physical activity (PA) tracking	Self- Monitoring, feedback	CP (with prompting) and PC	A physical activity tracker encourages participants to track the type and minutes of each activity throughout the day.
Buddy system (random pairing every 4 weeks).	Social support, accountability	CP	This component pairs each participant randomly and anonymously each month with a “buddy” who is also a study participant. Buddies can send pre-scripted messages or construct their own messages from a pool of keywords. Messages can be encouraging statements or advice and tips for overcoming certain lifestyle challenges. Buddies can also view a basic profile of each other without revealing their identity.
Goal setting	Goal setting, Action planning	CP (with prompting) and PC	A goal-setting feature that allows participants to set own or select from a list of pre-determined goalsand to track if goal is achieved.
Countdown	Goal setting, Action planning	CP	A goal-setting feature that allows participants to set a weight goal to achieve before the end of the study and to receive feedback on her or his progress toward that goal.
Challenge/game	Motivation enhancement, Positive re- enforcement	CP	Game or challenges to encourage Usage of phone or increase physical activity.
Rewards	Positive re- enforcement	CP	Rewards in the form of cartoons, video links or blog entries are sent to participants when they accomplish a certain level of tracking.