Individual Differences in Eating Behaviours and Their Relationship with Motivation, Cognition and Weight Control
A considerable percentage of the UK population are overweight (BMI≥25kg/m2) or obese (BMI≥30kg/m2). However, despite living in the same culture and exposed to a similar “obesogenic” environment, some individuals gain weight while others do not (French et al., 1995). This variability in weight control has been suggested to be associated with individual differences in eating behaviours (French et al., 2012). Certain factors, such as motivation (hedonic hunger and hunger status) as well as cognition (impulsivity and memory) may have an impact on eating behaviours and their relationship with weight control. Thus, the objective of this thesis was to explore individual differences in eating behaviours and investigate their relationship with motivation, cognition and weight control. The first experiment (Chapter 2) investigated the relationship between eating behaviours, motivation (hedonic hunger) and food consumption during an ad-libitum buffet. This study suggests that restrained eating behaviour was associated with higher overall energy intake, greater energy intake from unhealthy foods and greater energy intake from both high and low energy dense foods. However, no interactions between restraint and disinhibition or hedonic hunger was seen. Following this, the second experiment (Chapter 3) examined whether eating behaviours, such as disinhibition, restraint and hunger, change during a weight loss and weight maintenance period and whether they could predict changes in weight during these periods. Indeed, the results suggest that lower baseline restraint could predict greater weight loss during a low-energy liquid diet and interventions which increase restraint and decrease disinhibition may be beneficial for longer term weight maintenance. The third experiment (Chapter 4) was designed to investigate whether motivation and cognition influences eating behaviours. The results suggest that hedonic hunger, restraint and impulsivity may lead to higher levels of disinhibited eating behaviour. This study was also able to replicate the findings of previous literature suggesting that episodic memory is negatively associated with BMI (Cheke et al., 2016). Finally, following on from the previous study results, the fourth experiment (Chapter 5) included a more diverse sample of participants including dieters. The results provide evidence that individuals on a diet have poorer episodic memory ability than those currently not on a diet. This study also extended previous results suggesting that hedonic hunger (but also episodic memory and hunger) are important factors in disinhibited eating. Hedonic hunger was also shown to be important in levels of hunger.