Open Access
Original Article, Biomed Biopharm Res., 2023; 20(1):37-50
doi: 10.19277/bbr.20.1.310; PDF version [+]; Portuguese html [PT] 



Social networks and food choice of adolescents from a school in the Lisbon region

Ana Carina Almeida 1 & Bruno Sousa1, 2, 3  ✉️

1 - School of Sciences and Health Technologies, Universidade Lusófona de Humanidades e Tecnologias, Lisboa, Portugal
2 - CBIOS - Center for Biosciences & Health Technologies, Universidade Lusófona de Humanidades e Tecnologias, Lisboa, Portugal
3 - Health Service of Autonomous Region of Madeira



The use of social networks (SNs) leads to the development of autonomy and identity construction by young people, which may influence their food choices. The aim of this cross-sectional observational quantitative study was to determine the relationship between SNs and food choices of adolescents from a secondary school in the Lisbon region, according to the time of SN use. 
Data were collected at school using a Google Forms questionnaire for adolescents aged 16-19 years who used SNs. A sample of 176 participants was obtained.  Of these adolescents, 60.2% used SNs less than four hours daily, while 39.8% used SNs more than four hours. In the lower SN usage group, the majority were boys (53.80%), while the majority were girls (61.40%) in the higher usage group (p<0.05). No statistically significant differences between adolescents who use the SNs less than or more than four hours daily were detected. In this study, no relationship was found between time in SNs and adolescents' food choices. Further studies on this topic will be necessary.

Keywords:  Adolescents, food choices, Lisbon, social networks

To Cite: Almeida, A. C. & Sousa B. (2023) Social networks and food choice of adolescents from a school in the Lisbon region. Biomedical and Biopharmaceutical Research, 20(1),51-63

Correspondence to: This email address is being protected from spambots. You need JavaScript enabled to view it.     
Received 14/02/2023; Accepted 12/06/2023



Adolescence is a period of transition from childhood to adulthood, corresponding to ages between 10 and 19 years, according to the World Health Organization (1).  This is a period of explosive development both physically and psychologically, especially during puberty, which is characterized by an increase in risk behaviours and emotional swings (2). Thus, encouraging healthy eating in adolescents is not easy, since this age group is highly influenced by external environmental factors and environment (3).

Currently, young adolescents grow up in a society where digital technology is increasingly developed. Social networks (SNs) occupy a large part of their leisure time, and in recent years screen time has been increasing significantly (4). More than 90% of adolescents have at least one account on SNs (5).

The use of these digital platforms leads to the development of autonomy and identity construction by young people, contributing to the shaping of their personality, which will have an influence on their lifestyle habits (6).

In addition, marketing strategies are very well outlined and increasingly the focus is on the digital medium. Advertising through public figures and influencers has teenagers as the main target audience, which can be worrying, as this age group has a lower critical sense towards marketing strategies than the older public, thus becoming more vulnerable (7).

Social norms also seem to have an impact on eating behaviour, i.e., publications about certain foods, recipes or restaurants that become trendy, seem to influence adolescents' food choice, increasing their consumption (8).

SNs could be an excellent strategy for food education, as it is a place where adolescents spend much of their time (9). Early learning, exposure to new ideas and access to informative nutrition content could be beneficial for adolescents (10). However, while they can be a good means for health promotion, the best strategy for their use is not entirely clear (11).

The content about food available on SNs is increasingly common and easily triggers sensations in those who follow them, impacting food cravings, albeit unconsciously (12).

There is an increasing intervention by organisations and health professionals in SNs, with more and more online engagement with the general public (13). Many young people now use SNs for health content searches (13).

It is, therefore, of utmost importance to understand the adolescents' eating behaviour and how the SNs may influence them, so that nutritionists can develop strategies for food education in the digital environment, ensuring good nutritional literacy from an early age.

On the other hand, there are no known studies on this topic in Portugal and international information is scarce.

The aim of this study was to determine the relationship between SNs and food choice of adolescents aged 16-19 years old from a secondary school in the Lisbon region, according to the time of SN use.


Materials and Methods

This study is a quantitative observational cross-sectional study.

This study was carried out at Escola Secundária de Caneças, which had ten classes of 10th grade, 11th grade and 12th grade, with a total of 720 students.  Three classes from each of these years were randomly selected, totalling 223 students, however, informed consent was only obtained from 192 adolescents. Taking into account the exclusion criteria: the non-use of SNs and ages below 16 years and above 19 years, 1 and 15 students, respectively, were excluded, thus the final sample composition was 176 adolescents.

After the authorisation from the Directorate, and the consent from the adolescents' parents/guardians, all participants, prior to data collection, agreed to participate in the study, giving their written informed consent to participate. Before completing the questionnaire, the purpose of the study and the variables to be assessed were described, ensuring data anonymity. This study was conducted following the ethical standards established in the Declaration of Helsinki.

Data collection was made on May 9, 2022, using a Google Forms questionnaire. The study was presented to the students in a classroom setting, where a QR code to access the form was provided and the students responded individually on their mobile phones.

The questionnaire used for data collection consisted of fifteen questions and was divided into four sections. The first section was composed of personal information such as age, sex and the level of concern about food ("None", "Little", "Fair" or "A lot"). The second with three questions, namely about the use of SNs, which SNs are the most used and the number of daily hours of use.  The third section with six questions: whether you follow and type of beads related to food; whether you have ever tried recipes from these beads; and the remaining four questions in this section were about the relationship of these beads with your eating routine, namely in the preparation of recipes, going to restaurants, consumption of healthy food and the amount eaten ("Increased", "Maintained", "Decreased"). Finally, the fourth section, with three questions, involving a food frequency questionnaire with the various food groups (Fruit, Vegetables, Sweet Snacks, Salty Snacks, Fast-Food, and Soft Drinks); another question on whether they consider that the information on food present on social media, to a certain extent, can replace a consultation with a nutritionist; and a question on whether they consider that the content present on social media has an influence on their food choices.

After closing the questionnaire in Google Forms, the answers were extracted into a Microsoft Excel document, where the 16 participants were eliminated according to the exclusion criteria of the study. All answers were then coded and the results extrapolated to IBM SPSS 28.0.1 - Statistical Package for the Social Sciences. Nominal variables are presented as percentage and absolute value and quantitative variables as mean and standard deviation. The distribution of selected characteristics between the groups was compared using Pearson's chi-square test for categorical variables. The significance level was set at p<0.05.



This study was composed of a sample of 176 adolescents. The average daily time spent using social networks was 4 hours, with a variation between 30 minutes and 16 hours daily (SD=2.87). Of these adolescents, 106 used social networks less than 4 hours daily, while 70 said they used more than 4 hours daily.

In Table 1, it is possible to analyse the characterisation of the sample according to the time of SN use.

Table 1 - Characterization of the sample according to the time of use of SN.
Data expressed as mean (standard deviation) or percentage (n). Abbreviation: SN, Social Networks. ª P values for comparisons between groups were tested by Pearson χ2 .


Of the 176 adolescents who participated in the study, 52.30% were female (n=92). In the group that uses SNs less time, most were male (53.80%) and in the group that uses more hours daily, most were female (61.40%), with statistically significant differences in gender between groups.

The mean age of the sample was 16.98 years (SD=0.90), ranging between 16 and 19 years old. There were no statistically significant differences in age between the groups.

Regarding the level of concern about food, the majority (58.5%), reported having a "Reasonable" concern, with no statistical significance between the groups.

The SN most used by adolescents is Instagram (48.30%) and the second is Tik Tok (30.70%). However, no statistically significant differences were found between the groups. When asked whether they followed food-related accounts more than half answered "Yes" in both groups, however this percentage was higher in the group that uses SNs less than 4 hours daily (55.70%).

Those who stated that they follow food-related accounts on the SNs (n=99) were asked what type of account they mostly follow. 41.40% of the adolescents stated that they follow "Influencers", with "Nutritionists" being the option with the second most answers, with 23.20%. Table 2 analyses the type of food-related accounts and their relationship on the adolescents' eating habits according to the time of SN use.

Table 2 - Tracking of food-related accounts and their relationship with adolescents' eating habits as a function of time of SN use.
Data expressed in percentage (n). Abbreviation: SN, Social Networks. ª P values for comparisons between groups were tested by Pearson χ2. 


When questioned about the preparation of recipes from these same accounts, the vast majority (82.8%) answered "Yes". As for the relationship that these accounts have on the eating habits, they were asked about the preparation of recipes, trips to restaurants, consumption of healthy food and the amount eaten. We can see that 72.70% reported an increase in the preparation of recipes, and as for restaurant visits, around 54.50% reported that they remained the same. The distribution of this answer was similar in both groups. In relation to the consumption of healthy food, 56.60% reported increasing consumption. With regard to the quantity ingested, the answer was unanimous in both groups, with the great majority replying "It remained the same". There were no significant differences between the groups.

Table 3 shows the frequency of consumption of several food groups by adolescents according to the time of use of SNs. However, there were no statistically significant differences between the groups regarding all food categories.

Table 3 -  Frequency of consumption of some food groups as a function of time of SN use
Data expressed in percentage (n).  ª P values for comparisons between groups were tested by Pearson χ2. 


Table 4 represents the adolescents' perception of the influence of SNs according to the time of SN use.

Table 4 - Adolescents' perceptions of the influence of SNs as a function of time of SN use.
Data expressed in percentage (n). Abbreviation: SN, Social Networks. ª P values for comparisons between groups were tested by Pearson χ2. 


When asked whether the information in SNs replaces a nutrition consultation, 84.10% answered "No", with a similar distribution of answers in each of the groups.

When asked if the content present in the SNs influences food choices, 49.40% answered "Yes" and 50.60% answered "No". There were no statistically significant differences between the groups.



According to the results obtained, Instagram seems to be the social network most used by these adolescents. A study developed in a sample of young people aged between 15 and 21 years refers the same preference (14). This information will be useful for health professionals and health institutions so that they can act strategically, if necessary, since it is the SN most used by adolescents.

The average number of hours of daily SN use in this study was 4 hours. However, a recent study published on the We Are Social website states that this figure is quite variable from country to country. In the Philippines, the average daily hours is 4 hours and 15 minutes, while in Japan it is only 51 minutes. This factor variability could trigger different outcomes in different countries (15).

The group that uses more hours daily the SNs showed more frequent consumption of fast-food, although not statistically significant. A study was conducted in Australia on adolescents using SNs, which assessed the impact of fast-food advertising on adolescents' consumption intention.  According to these authors, fast-food advertisements seem to influence and increase the likelihood of eating this type of food (16). On the other hand, in a recent review based on a study conducted between 2017 and 2022, it was reported that food advertisements on social media often focus on promoting the consumption of unhealthy foods and beverages, and that this fact is associated with increased consumption among adolescents (17). This may justify this consumption, since individuals who spend more time in SNs are more exposed to advertising.

Most adolescents who follow food-related accounts on SNs stated that these accounts have an impact on increasing consumption of healthy foods and recipe preparation. According to a study also developed in Lisbon, the same was found, and the accounts from which they try more recipes are from nutritionists (12). In another study in Greek adolescents and young adults, publications on healthy eating and new recipes were also found to be inspiring, and although images of appealing but less nutritious foods seemed to create the need for participants to consume these foods, the majority ended up not doing so (18).

Of the adolescents who followed food-related accounts on SNs, the majority claimed to follow mostly influencers, with this value being higher in the group of youngsters who use SNs for more than 4 hours a day, despite the fact that it does not present statistical significance. According to Kucharczuk, the presence of influencers and public figures in food and beverage advertising campaigns in their SNs influences adolescents, especially in the consumption of unhealthy foods (5). Thus, the group that uses more SN hours seems to be more exposed to this type of temptation.

When asked if they considered that SNs influenced their food choices, the answers were divided between "Yes" and "No". However, in a study developed in Porto in 2018, also in a sample of adolescents, the exact same question was asked and the majority (60.00%) answered "Yes", assuming that SNs influenced their food choices (14). The answer to this question is only a self-perception of the adolescents, which can be undervalued or overvalued, and is based only on the opinion of young people who may unconsciously be influenced by marketing strategies and cannot identify it (7).

This study has some limitations, namely the fact that the questionnaire is not validated, it is a cross-sectional study, the sample size is small and the sample is very homogeneous, since data were collected in only one school, with homogeneity in demographic, socio-economic and lifestyle issues, which may have biased the results.

However, this study also has strengths, such as the fact that it was the first study in Portugal to assess the relationship of SNs on food choice in a sample of adolescents aged between 16 and 19 years old, according to the time of SN use.

This study may be useful for future meta-analysis and development of studies on the topic, containing a more representative and heterogeneous sample, in order to reach a conclusion with statistical significance.

As future prospects, it will first be essential to study how adolescents behave in SNs and how these may impact their diet. Health professionals, in this case nutritionists, may then develop strategies for food education in the digital environment, since this environment tends to grow in future generations.



With this study, it was possible to conclude that there were no differences in food choices between adolescents who use SNs less than four hours and those who use more than four hours daily. The possibility is thus assumed that there is no relationship between the time of SN use and the adolescents' food choices.

Thus, further studies on this topic, containing a more quantitatively representative and heterogeneous sample, will be necessary to strengthen the conclusions of this study.


Authors' Contributions

A.C.A.: conceptualisation and design of the study; implementation; data analysis; tables; writing. B.S.: editing and revision; supervision and final drafting.



The authors would like to thank Escola Secundária de Caneças for the opportunity and prompt availability to carry out this study and the students who participated in this study.


Conflict of Interest

The authors declare that there are no conflicts of interest.



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