The perception of sweet, bitter and fatty acid taste and sensitivity to fat by mouthfeel and olfaction : associations with dietary intake, eating behaviour and obesity in premenopausal women : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Albany, New Zealand

Background: Individual variability in taste perception may influence diet, possibly modifying eating behaviour and long-term food choice. Research into taste perception and weight status, dietary intake, eating behaviour and endocrine regulators of metabolic health could provide new important insights. Taste perception may be modifiable, and as such may be a target for future intervention strategies which may have the potential to prevent or treat obesity. Objectives: The aims of this study were to determine associations between (1) fatty acid taste, olfaction, mouthfeel of fat, dietary intake, eating behaviour and body mass index (BMI), and (2) associations between taste perception of glucose (sweet taste), quinine (bitter taste) and milk (fat perception) with body composition and hormonal adiposity signals (fasting insulin and leptin), dietary intake and eating behaviour. Design: For the first cross-sectional study, 50 premenopausal women assessed oleic acid taste and olfaction thresholds. BMI was calculated from weight (kg) and height (m). Dietary intake and eating behaviour were evaluated using a food frequency and three-factor eating questionnaire (TFEQ), respectively. Binomial regression analysis was used to model fatty acid taste and olfaction data and fatty acid taster status was determined (hypersensitive, n= 22; hyposensitive, n= 28). For the second cross-sectional study (the PROMISE study), 351 premenopausal Pacific and New Zealand (NZ) European women were recruited and stratified by non-obese and obese groups. Suprathreshold intensity, hedonic liking, and discrimination of taste by a ranking task were measured using a range of concentrations of sweet, bitter, and fat solutions. Participants were classified as likers or dislikers for each tastant using a hierarchical cluster analysis. Body fat (BF) was quantified by dual x-ray absorptiometry. Total energy and macronutrient intake were assessed using a 5-day estimated food record and eating behaviour was a