ÖAW-DOC Stipendium für Andreea-Georgiana Cristian zum Thema "From Lab to Life: Investigating variations in stress-eating through a combined methodological approach", 36 Monate

Obesity rates are rapidly increasing worldwide, which calls for immediate action to prevent health-related complications, such as cardiovascular complications, diabetes, or cancer (Afshin et al., 2017). A main driver of this increase is an obesogenic environment filled with unhealthy and energy-dense food options (Swinburn et al., 2011), likely to increase unhealthy food consumption. Despite that laypeople have a basic understanding of what constitutes a healthy and unhealthy diet (de Ridder et al., 2017), stress constitutes a main driver for promoting unhealthy behaviour. Stress, conceptualised as a psychological and physiological experience, was shown to influence our eating habits; however, this link is inconsistent. Specifically, it is unclear why individuals resort to overeating, undereating, or maintaining their behaviour when experiencing stress (Hill et al., 2022). Most of this research has been conducted in laboratories, yet it was criticised for a lack of ecological validity and ecological fallacy to generalise the results to our daily life (Schlotz, 2019). Daily life research has inconsistently shown the effect of stress on eating. While some studies found an effect between daily hassles and snack intake (Finkelstein-Fox et al., 2020; O'Connor et al., 2008), others found no association between perceived stress experiences and healthy eating (Schultchen et al., 2019), perceived food intake (Reichenberger et al., 2021), as well as actual food intake (Ruf et al., 2023). It is unclear whether stress affects eating in daily life, considering that ecological momentary assessment is limited in capturing the variability of stress in naturalistic settings (Reichenberger et al., 2021) and relies on using unvalidated measures in this endeavour. Experimental settings are renowned for high internal validity to establish causalisation (Schlotz, 2019). Instead of comparing findings from daily-life and experiments to pinpoint the sources of inconsistency, we propose a combined solution to overcome the limitations of both designs. We propose that a combined approach of experimental and real-life assessments is a strong solution to mitigating the inconsistent findings related to food intake by overcoming the limitations of both paradigms and examining the relationship between stress-eating from the laboratory to real-life settings.

This research will be structured in two main stages and a potential third stage:
• Study 1: Investigate the psychometric properties of daily stress measures used in health research (Bamert et al., 2025) and their corresponding correlation with continuous heart rate and cortisol measures for the course of seven days. This study will be used to identify reliable stress measures and establish their validity with objective stress measures.
• Study 2: Examine whether and under which circumstances perceived stress predicts within-person fluctuations in actual food intake and food healthiness in low- and high-stress contexts in experiments and daily life. This study is key to examining the association between lab-measured and EMA-measured stress eating.
• Study 3: Provided that daily stress measures are reliable and valid in capturing stress responses (in Study 1), we will employ in parallel with Study 2 physiological heart rate assessments to understand how physiological and subjective stress responses relate to eating practices.

Research Question & Hypotheses. These studies aim to answer the overarching research question: “How does lab-measured stress reactivity relate to stress-induced eating patterns and food choices from daily life?” To this end, we hypothesise a positive correlation between subjective and objective daily stress measures (Study 1), an association between perceived stress and food intake in both the experiment and daily life, and a positive and negative relationship between stress and unhealthy and healthy eating, respectively (Study 2). For study 3, we will explore how physiological stress (i.e., heart rate) relates to eating behaviour. To answer the overarching research question, we assume a positive relationship between lab-measured and EMA-measured stress-eating, provided that the same phenomenon is observed.

Originality & Innovation. The goal of this innovative methodological solution is to bridge two established paradigms for studying stress-eating link, solve empirical debate, and understand whether and under which circumstances stress-eating needs to be addressed in dietary interventions to promote health and well-being. Academic Environment. I will also apply for the scholarship of Vienna Doctoral School of Cognitive, Behavioural and Neuroscience (CoBeNe), part of the University of Vienna. Only upon successful admission, I will be based in CoBeNe and in the Department of Clinical and Health Psychology.

There, I will work with the following research team:
• Prof. Dr. Laura M. König is an expert on healthy eating behaviours with vast experience in photo-based assessments of food pictures (e.g., König, 2018; König et al., 2021) and EMA (Wahl et al., 2017). Prof. Dr. König will be my supervisor.
• Prof. Dr. Urs M. Nater is an expert on stress research with ample experience with (biomarkers of) stress in experiments and EMA assessments of stress (Feneberg & Nater, 2022; Nater et al., 2013). Prof. Dr. Will be a collaborator on this project.
• Dr. Alea Ruf, a collaborator, has specific experience on stress and food intake in daily life (Ruf et al., 2023) and experience with advanced multilevel modelling (Ruf et al., 2021).