Table 2.

Features and main results of general and feedback messages included in different studies.

App name	Objective	Features	Main results	References
My fitness pal	Weight management	General message topics: Nutritional knowledge, good and not so good food choices, and predictions of future body weight based on daily intake	Although most users rated the messages positively, some expressed concern regarding: i) obvious statements, ii) indication of poor food choices despite users' low consumption of the same, iii) long-term weight predictions based on current daily intake and iv) negative messages.	(8)
Children eating well (CHIEW)	To increase the intake of fruit, vegetables, fiber, and water and reduce the intake of sugary drinks, through parental' information.	- General message topics: Healthy snack recipes; beverage recommendations (including milk); child appropriate snacks; introduction of new foods; and reminders to use the application -Message frequency: Varied number of notifications weekly. Each message was repeated twice every 3 months. - Time of the messages: 10:00 am, although the user could changed it	- New fruits and vegetables introduced - Sugary drinks reduced and substituted by water - Parents offered their children more fruit and vegetables - Improvement in diet	(29)
ONCOFOOD	To improve the dietary goals of cancer patients.	-Daily diet record reminder messages (9:00, 13:00 and 19:00) -Weight record and weekly appetite parameter reminder message by acoustic signal at 17:00.	Those who used the application met 100% of the protein, fat, and energy requirements, compared to the control group that did not reach this goal. Compared to the control group that lost weight (1.03 kg vs. −1.46 kg) as well as muscle mass (0.58 kg vs. −0.61 kg) the group that used the application gained weight significantly	(50)
PYNC	To promote healthy habits (physical activity, healthy weight, calorie intake reduction, healthy diet) for reducing the risk of breast cancer	-General message topics: educational information on the benefits of weight loss through healthy eating, increasing consumption of fruit and vegetables, reducing intake of sugar or red meat, limiting alcohol intake, promoting physical activity, etc.) -Feedback message about calories burnt -Daily intake reminder messages and challenges reminders (every hour g if you had not reached the 250-step challenge)	Volunteers preferred simple language, visually presented information, easy-to-prepare healthy recipes, suggestions for grocery shopping or refrigerator ordering, and strategies for interpreting food labeling	(26)
Txt4happy kids	To increase fruit and vegetables consumption in families with children	General messages: -Frequency: two messages / week -Length: 160 characters -About benefits of consuming fruit and vegetables -Strategies to promote the consumption of fruit and vegetables (e.g., making purchases, cooking together, leading by example, etc.) -Healthy recipes -Fruit and vegetable price reduction advertisements	92% of parents offered more fruit and vegetables to their children because they were aware of the benefits. 86% tried to follow a healthy diet. 85% tried different recipes with fruit and vegetables. 81% were concerned about what their children were consuming. Moreover, 83% agreed that the presence of fruit and vegetables at home had increased since the study. Although, message strategy alone does not seem enough to increase fruit and vegetable consumption	(30).
Body quest parent	To prevent obesity and improve healthy eating habits in children (increased vegetable consumption)	General messages: -Frequency: three messages/week -Content aimed at changing behavior patterns regarding vegetable consumption -Preparing vegetable dishes at home	Significant increase in vegetables consumption	(25)
	To decrease consumption of sugary drinks and juices.	-Messages with recommendations, motivation, and advice on progress (3–4/ week) -Weekly feedback messages about consumption	Significant decrease of 287 mL/day compared to the control group (50 mL/day) and weight decrease by 2.4 kg compared to a gain of 0.9 kg in the control group	(28)
	To increase knowledge on Type 2 Diabetes: prevention, treatment, and management	General messages: -Frequency: two times/week, every 3 months -Length: 160 characters -Content: information on type 2 diabetes	Significant increase in knowledge about the pathology among the intervened group compared to the control group.	(51)
	To promote nutritional behavioral changes in children through parents.	General messages: -Information to promote reflection, discussion, and action -Content: specific portions of healthy foods for different ages, healthy recipes, specific information on nutritional advice and education on healthy eating for children -Includes links for more information: eating habits, dietary quality, preparation of dishes and recipes, family menus and healthy snacks Length: 160 characters	Both parents, experts, and their group evaluated the clarity, usability, and relevance of the messages with 4 points out of 5	(52)
	To increase fruit and vegetables consumption. To reduce the consumption of food with a low nutrient density and sugary drinks	Feedback messages: -Frequency: 1 message/week -Features: personalized with the name of each user, motivational, suggestion of healthy alternatives, including nutritional advice and simple concepts General messages: -Frequency: 1–2 times/week -Between 4 p.m. and 6 p.m. -Features: examples of everyday situations of higher risk of consuming unhealthy foods and healthy suggestions to avoid it, recipe links or nutritional information	Significant reduction in weight (1.7 kg) in experimental group; consumption of low nutrient density foods in experimental group (1.4 servings/day, in men) and consumption of sugary drinks (0.2 servings/day) in experimental group regarding control, in women	(14)
TreC-LifeStyle	To provide nutritional education for families with overweight children	-Daily reports summarizing the deviations and adequacy of their dietary intake with respect to a healthy diet -General messages with nutritional content: advice on a healthy diet, with a frequency of one message/day	The results showed a good adherence to the app with> 90% of the meals recorded over 6 weeks, demonstrating a good acceptance app over the 6 weeks. The parents declared usability as very positive Participants stated that they were influenced by the feedback provided	(6)
	To reduce the weight of an obese population	-Feedback messages: After recording weight, the application automatically provided users with a personalized feedback message about their progress and tips	Significant weight loss in the group intervened: 43% of the patients in the intervention group were more likely to lose 5% or more of their original weight at 6 months, compared to 6% of the patients in the usual care control group	(53)
	To study the tone, content, and length of nutritional messages	General messages: -Content: recommendations on fruit and vegetables, fast food, and alcohol -Length: 2-3 sentences -Tone: empathetic, authoritarian, colloquial, based on solutions or healthy alternatives	22 and 29% of respondents indicated that the empathetic tone and the messages based on solutions or healthy alternatives, respectively, were the most persuasive strategy to produce improvements in diet, compared to the others that obtained a lower percentage of choice.	(54)
Diet-A	To monitor intake in adolescents	-Registration reminders (11:00, 15:00, and 20:00) -Feedback message topics: energy, carbohydrates, protein, fat, saturated fat, calcium and sodium	61.9% of users said they were satisfied after using the application for monitoring their intake Significant reduction in sodium intake	(31)
	To increase vegetable consumption among young adults.	General messages: 1–2 sentences; tips on how to introduce vegetables in the weekly menu; motivational message describing the healthy benefits of fruit	The text messages promoted motivational changes in the consumption of fruit and vegetables	(55)