Abstract
Background: Many midlife women engage in maladaptive restrained and weight focused eating behaviours (e.g., dieting) which are associated with negative psychological and physical health outcomes. Intuitive eating, an alternative eating style characterised by individuals’ eating in response to their physical hunger and satiety cues, honouring health with nutritious food, and fostering a positive relationship with food, has been shown to have positive psychological and physical health outcomes. However, adopting and maintaining this way of eating can be difficult due to their deeply engrained dieting mentality. As motivation plays a central role in behaviour change, an investigation into women’s motivations for eating behaviour, their relationship to intuitive and maladaptive eating behaviours, and how social environments influence those motivations and outcomes could help facilitate women to eat more intuitively.
According to self-determination theory (SDT), six different types of motivation exist which sit along a continuum of self-determination. Individuals will display varying levels of each type of motivation which represents their motivational profile. The nature of these motivational profiles are associated with behavioural and psychological outcomes. SDT states that the basic psychological needs (BPN) for autonomy, competence, and relatedness are essential for understanding the role of the social environment in influencing motivation and behaviour. Previous literature has only explored the relationship between combined scores for autonomy, relatedness, and competence, combined scores across the types of motivation, and maladaptive eating. In order to gain a comprehensive understanding of the motivational determinants of eating behaviour, an exploration of the BPN, motivational profiles for eating behaviour, and their relationship to intuitive eating was conducted.
Objective: The overall aim of this research was to investigate the motivational profiles for eating behaviour that exist among midlife women, outcomes associated with them, and predictors of the motivational profiles. To achieve this aim, the thesis objectives were to (1) identify motivational profiles for eating behaviour and examine the profiles with respect to the outcomes of intuitive eating and maladaptive eating behaviours and self-reported health; (2) examine the extent to which BPN satisfaction and frustration explain the motivational profiles and intuitive eating and maladaptive eating behaviours; and (3) explore the experiences that midlife women encounter in their social lives and how these experiences are interpreted as satisfying or frustrating their needs for autonomy, relatedness, and competence.
Methods: Objectives 1 and 2 were addressed using a cross-sectional survey research design. Using sponsored advertisements on Facebook, New Zealand women aged 40-50 years were recruited to complete an online survey. Women (n = 472) completed measures to assess SDT-based motivation for eating behaviour, intuitive eating and restrained, emotional, and external eating (maladaptive eating behaviours), and self-reported health. They also completed a measure of the satisfaction and frustration of the BPN in the eating context, which was adapted and validated for the purposes of this research. Novel bifactor S-1 exploratory structural equation modelling was used to model the women’s motivation for eating behaviour. Latent profile analysis was used to identify motivational profiles and chi-square analysis compared the derived profiles on the outcome variables (eating behaviour and health outcomes) and predictors (the BPN).
Objective 3 was addressed using a qualitative research design. Women who exhibited an externally or amotivated motivational profile from the survey-based research were purposively recruited to undertake a semi-structured interview via Zoom. Questions were asked that explored the women's perceptions of how people or situations have influenced their eating behaviour. Interview transcripts from the 14 women who participated were analysed thematically using Braun and Clarke’s reflexive thematic analysis. Firstly, the eating-related experiences that midlife women encountered in their social lives were identified inductively. Secondly, these experiences were analysed deductively where they were interpreted as either satisfying or frustrating their needs for autonomy, relatedness, and competence.
Results: Five distinct motivational profiles were identified: (1) self-determined (57% of women), (2) internalised (11%), (3) externally motivated (8%), (4) amotivated (11%), and (5) unmotivated (13%). Women in the self-determined profile had higher intuitive eating and lower maladaptive eating scores and reported higher psychological and physical health scores compared to the sample average. Women in the internalised profile had higher physical health scores but lower psychological health scores and also had mixed results related to intuitive eating and maladaptive eating. Women in the externally motivated, amotivated, and unmotivated profiles tended to have lower intuitive eating and higher maladaptive eating scores and reported lower psychological and physical health. Each profile had differing levels of satisfaction and frustration of the three needs. As expected, women belonging to the self-determined profile had higher levels of autonomy and competence satisfaction and lower levels of autonomy, relatedness, and competence frustration compared to the sample average. The internalised profile had lower levels of autonomy, relatedness, and competence satisfaction, and higher levels of autonomy frustration. The externally motivated, amotivated, and unmotivated profiles had lower levels of autonomy and competence satisfaction, and higher levels of autonomy, relatedness, and/or competence frustration.
Two themes were generated in the qualitative study. The first, labelled “Pressure to eat in particular ways”, described the experiences where the women felt that their eating choices were being dictated. This theme comprised three subthemes that explained where that pressure originated from: (1) childhood experiences, (2) explicit pressure from others, and (3) internal pressure. The second theme labelled “Sense of control: Managing eating amid resource constraints”, described the internal and external factors that caused the women to feel a lack of control over their eating. Their narratives conveyed that the women felt their needs were primarily being frustrated through their experiences and that women would compromise their needs for autonomy and competence in order to satisfy their need for relatedness.
Conclusions: The results showed the complex ways in which different types of motivation combine within an individual to impact eating behaviour and health. A motivational profile with higher self-determination towards eating appears to be the most beneficial for promoting greater intuitive eating behaviours and health outcomes, and lower maladaptive eating behaviours. Autonomy and competence satisfaction appears to be important for promoting a profile with higher levels of self-determination. Women belonging to profiles low in self-determination and high in external regulation or amotivation interpreted many of their experiences in the eating context as frustrating their needs for autonomy, relatedness, and competence. Understanding the specific ways in which need satisfactions and frustrations are experienced is essential for guiding interventions aimed at enhancing need satisfactions and reducing need frustrations, ultimately promoting self-determined motivation and intuitive eating behaviour. SDT informed eating behaviour interventions that satisfy the needs (especially autonomy and competence), and reduce all three need frustrations, may lead to motivational profiles with higher self-determination.