Our Research Areas

Why do we eat what we eat? When asked, people give all kinds of answers, yet frequently overlook one of the most important reasons: social context. Eating is a social activity. Eating together is more than food intake, it deepens social bonds, fosters appreciation, and aids information exchange – eating together is often more important than the healthiness of the food (think birthday cake!).

We use tools of the psychological and computational social sciences to study the social factors influencing how we eat. We conduct experiments, everyday observations (such as experience sampling studies), video recordings in the lab, and panel studies. We analyze data from social media, conduct meta-analyses, and work on the theoretical foundations of eating in a social context.

Is eating together healthy?

It depends. For example, in couples, we find that people primarily gain weight when they move in together or get married; only separation is associated with weight loss (Mata et al., 2018). We attribute this weight gain and associated changes in diet primarily to the new social environment. Families are a different story: Children eat more fruits and vegetables and have a healthier body weight if they eat more often with the family. It is also helpful if the TV is turned off during meals, parents are role models and eat vegetables, or the mealtime atmosphere is positive (Dallacker et al., 2018, 2019). Young adults are more likely to make friends with others who have similar food preferences as themselves – and they also adapt to their friends over time (e.g., in how much meat they eat). In the context of social media, posting can support fruit and vegetable consumption (Kilb et al., 2022). We are currently working on further developing theories of eating in a social context and conducting empirical studies in a wide variety of social contexts to test these theories.

Selected Publications

• Kilb, M., Giese, H., & Mata, J. (2023). How eating-related social media postings influence healthy eating in senders and network members: Two field experiments with intensive longitudinal data.Appetite.
• Knobl, V., Dallacker, M., Hertwig, R. & Mata, J. (2022). Happy and healthy: How family mealtime routines relate to child nutritional health. Appetite, 171(Article 105939). doi.org/10.1016/j.appet.2022.105939
• Dallacker, M., Hertwig, R. & Mata, J. (2019). Quality matters: A meta-analysis on components of healthy family meals. Health Psychology, 38(12), 1137–1149. https://doi.org/10.1037/hea0000801
• Dallacker, M., Hertwig, R. & Mata, J. (2018). The frequency of family meals and nutritional health in children: A meta-analysis. Obesity Reviews, 19(5), 638–653. https://doi.org/10.1111/obr.12659
• Mata, J., Richter, D., Schneider, T. & Hertwig, R. (2018). How cohabitation, marriage, separation, and divorce influence BMI: A prospective panel study. Health Psychology, 37(10), 948–958. doi.org/10.1037/hea0000654

Healthy eating and sustainability go hand in hand: More plants, less meat, more seasonal and less highly processed products not only reduce the risk of chronic degenerative diseases, they also protect animals and the environment (and in turn human health).

Detailed information on all these aspects is just a mouse click away – why do so many people nevertheless choose to rather not know exactly where their meat comes from or what the consequences of eating meat can be? We investigate why people are deliberately ignorant, how such ignorance can be overcome, and what consequences newly gained knowledge can have.

Meat eating takes place in a social context. People choose friends with similar meat consumption and also adapt their consumption to each other (Herwig et al., 2022). Currently, we are studying how families negotiate their meat consumption, how people who eat vegetarian or vegan diets are perceived, and how they change their social environment in line with their health and ecological goals.

We work with psychological and computational social science methods, conduct experiments and panel studies, and analyze social network data and social media data to understand eating behavior.

Selected Publications

• Herwig, I. E., Giese, H., & Mata, J. (2022, August 23 – 27). (M)eating like your friends? Social Friendship Networks and Meat Consumption [Conference Poster Presentation]. European Health Psychology Society Conference, Bratislava, Slovakia. https://osf.io/dh9fa/
• Inauen, J., Contzen, N., Frick, V., Kadel, P., Keller, J., Kollmann, J., Mata, J. & van Valkengoed, A. (2021). Environmental issues are health issues: Making a case and setting an agenda for environmental health psychology. European Psychologist, 26(3), 219–229.
• Kadel, P., Herwig, I. E., & Mata, J. (2023). Deliberate ignorance—a barrier for information interventions targeting reduced meat consumption? Psychology & Health.

The life expectancy of people with a higher level of education in Germany is up to 11 years longer than that of people with a lower education level. Comparable numbers are also found for income. Findings for people with a migration history are mixed: on the one hand, people who have recently migrated are on average healthier, while their children (in the second migration generation) fall ill significantly more often and live shorter lives. Where do these differences come from? One key are health behaviors, such as exercise and diet.

We examine how socioeconomic groups differ in their thinking about health behaviors, their health behaviors, and the effectiveness of health interventions (e.g., Klink et al., 2022; Mata et al., 2022; Schüz et al., 2021). In this context, we find, for example, that in Europe, both lower-educated and higher-income individuals eat more meat.

Being different – be it through obesity (Emmer et al., 2020) or migration experience – is often related to stigma or discrimination, increased stress experience, and poorer mental health. Currently, we are exploring whether stress, in the context of migration and often related experiences of discrimination, can be mitigated through health behaviors.

To investigate these questions, we conduct meta-analyses, experiments, everyday observations (such as experience sampling studies), and panel studies.

Selected Publications

• Emmer, C., Bosnjak, M. & Mata, J. (2020). The association between weight stigma and mental health: a meta-analysis. Obesity Reviews, 21(1), e12935, 1–13.
• Emmer, C., Dorn, J., & Mata, J. (2022, August 23–27). The effect of discrimination on mental health: A meta-analysis of the causal evidence [Oral presentation]. European Health Psychology Society, Bratislava, Slovakia.
• Emmer, C., Kalter, F., & Mata, J. (2021, August 23–27). Associations of cultural identity with health behaviors and health outcomes [Oral presentation]. European Health Psychology Society, digital conference. 
• Klink, U., Mata, J., Frank, R., & Schüz, B. (2022). Socioeconomic differences in animal food consumption: Education rather than income makes a difference. Frontiers in Nutrition, 9:993379.
• Mata, J., Kadel, P., Frank, R., & Schüz, B. (2023). Education- and income-related differences in processed meat consumption across Europe: The role of food-related attitudes.Appetite.
• Mata, J. & Hertwig, R. (2018). Public beliefs about obesity relative to other major health risks: Representative cross-sectional surveys in the USA, the UK, and Germany. Annals of Behavioral Medicine, 52, 273–286.
• Schüz, B., Meyerhof, H., Hilz, L. K. & Mata, J. (2021). Equity effects of dietary nudging field experiments: Systematic review and meta-synthesis. Frontiers in Public Health, 9(Article 668998), 1–13. doi.org/10.3389/fpubh.2021.668998

There are clear guidelines and recommendations on healthy eating or physical activity. People who follow these guidelines have a lower risk of chronic degenerative diseases such as cardiovascular disease. Less research has been done on the effects of physical activity, diet, or eating behaviors on well-being and mental health.

Does physical activity always make people happier? If so, do I need to go jogging or is walking enough? Does snacking increase positive affect or guilt? Am I less stressed if I make sure I get a good night's sleep and exercise regularly? Can I also strengthen my ability to perform at university, for example, through health behavior?

Methodologically, we investigate these questions with intensive longitudinal studies and meta-analyses, we conduct experiments and measure exercise and sleep behavior via actigraphy.

Selected Publications

• Flückiger, L., Lieb, R., Meyer, A. H., Witthauer, C. & Mata, J. (2016). The importance of physical activity and sleep for affect on stressful days: Two intensive longitudinal studies.Emotion, 16,488–497.
• Kadel, P., Schneider, S., & Mata, J. (2020). Soft drink consumption and mental health problems: Longitudinal relations in children and adolescents.Social Science & Medicine, 258, 113–123.
• Mata, J., Wenz, A., Rettig, T., Reifenscheid, M., Moehring, K., Krieger, U., Friedel, S., Fikel, M., Cornesse, C., & Blom, A. G. (2021). Health behaviors and mental health before and during the COVID-19 pandemic: A longitudinal population-based survey. Social Science & Medicine, 287:114333.
• Mata, J.,Hogan, C. L., Joormann, J., Waugh, C. E., & Gotlib, I. H. (2013). Acute exercise attenuates negative affect following repeated sad mood inductions in persons who have recovered from depression.Journal of Abnormal Psychology, 122, 45–50.
• Mata, J., Thompson, R. J., Jaeggi, S., Buschkuehl, M., Jonides, J., & Gotlib, I. H. (2012). Walk on the bright side: Physical activity and affect in Major Depressive Disorder.Journal of Abnormal Psychology, 121, 297–308.