Some individuals exhibit a weak satiety response to food. This may have implications for appetite control and leave individuals susceptible to overconsumption. The current thesis examined the reliability and validity of the satiety quotient (SQ), a measure of satiety responsiveness. In a series of experimental studies SQ was examined in response to different foods and used as a means of identifying individuals with low satiety responsiveness, termed the ‘low satiety phenotype’. Using the SQ, normal weight (Chapters 4, 6 and 7) and overweight and obese (Chapter 8) individuals were categorised as either low or high in satiety responsiveness and were characterised by behavioural (energy intake, food choice), psychological (food reward, eating behaviour traits), physiological (body composition, gut peptides) and metabolic (resting metabolic rate) risk factors for overconsumption. Chapter 4 and 6 examined the reliability of the SQ as a measure of satiety responsiveness and investigated behavioural, psychological and metabolic risk factors for overeating in the low satiety phenotype. In Chapter 7, energy intake, food reward and appetite sensations were compared in the low and high satiety phenotype following the consumption of snack foods that differed in satiating potential. Finally, Chapter 8 investigated the relationship between gut hormones and satiety responsiveness. The low satiety phenotype were characterised by impaired capacity to detect appetite sensations and reduced intensity and duration of post-ingestive activity (Chapters 4, 6, 7 and 8). The low satiety phenotype exhibited greater wanting for high fat foods (Chapter 6), lower control over food cravings (Chapter 4), greater disinhibition (Chapter 6) and greater trait anxiety (Chapter 8), as well as greater energy intake across study test days (Chapter 6 and 7). While individuals differed markedly in their subjective expression of postprandial satiety, this difference did not appear to be encoded in changes in any of the single gut peptides measured in this research. The low satiety phenotype did however show a blunted glucose response (Chapter 8). In addition, it was found that the consumption of snack foods high in fibre and protein is one strategy to improve appetite control in the low satiety phenotype (Chapter 7). In summary, the satiety quotient can be used to identify a distinct, reliable low satiety phenotype. The low satiety phenotype appears to be characterised by behavioural, psychological and physiological factors associated with risk over overeating compared to the high satiety phenotype.
