**2. Related Work**

Health and obesity problems related to physical activity and diet have been studied in the past. Moreover, some interventions have been conducted to assess the impact of reminders in these domains. This section presents related works to the one described in this paper. Even though there are many

works focusing on comparing results of weight change, eating habits and physical activity in different contexts [11–13], we will only consider related works that use some kind of device or notification as a reminder for people.

In 2011, Monteiro et al., described a randomized controlled trial lifestyle intervention. Authors focused on nutrition and physical activity. Their study focused on mothers with young children (0–5 years old). The designed intervention used face to face workshops, emails and Short Message Service (SMS) reminders as notification mechanisms [14].

Also in 2011, Winett et al., described a program to assess nutrition, physical activity and body weight outcomes applying a social cognitive theory to health. This was a web-based intervention. Authors selected sedentary participants between 18 and 63 years old. With this intervention authors concluded that a simple web-based program can help people to comply with healthy behaviors [15].

Other studies focus more on behavior changing. For instance, in 2015, Hattar, Hagger and Pal, described a randomized control trial study protocol that developed psycho-education using implementation intentions and mental imagery (through videos). In this work authors developed and presented the protocol to evaluate the HEALTHI (Healthy Eating and Active LifesTyle Health Intervention) program. This is a theory-based intervention with the goal of changing dietary intake and physical activity behaviors in overweight people. Authors also propose the use of SMS in this work [16].

In 2016, Quintiliani and Whiteley, conducted a randomized trial to examine the feasibility of a nutrition and physical activity behavioral intervention. In this work, the communication mechanisms used were motivational phone calls from trained peer counselors. Even though authors reported no statistical differences between the control and intervention groups, the overall satisfaction with the program was high [17].

Finally, a category that has been study is the use of mobile apps to improve diet, physical activity and sedentary behavior. From studies combining SMS, emails, apps and websites [18], pregnant women using mobile phone as reminder and a Fitbit (Fitbit International Limited., San Francisco, CA, USA) as a control mechanism [19], textual and auditory cues delivered through a mobile app to increase fruit and vegetable intake and health literacy in general [20], all the way to mobile games using an activity trackers Tractivity (Kineteks Corp., Mainland, Vancouver, BC, Canada) as input to promote physical activity in children [21].

From the literature review conducted, we could not identify studies that used smart device-based notifications to promote healthy behaviors regarding snacking and physical activity to avoid or reduce overweight and obesity levels.
