A lifestyle of reduced physical activity and eating energy dense foods has resulted in a worldwide obesity epidemic. It is assumed that overeating is driven by hedonic rewards rather than by homeostatic factors of energy intake. Hedonic rewards are consummatory, 'liking' (e.g., satisfaction and palatability), or anticipatory, that is, 'wanting' (craving). Continuous patterns of wanting and liking of food as a potential explicit expression of reward anticipation and incentive salience, as well as consummatory reward perception have not yet been investigated in real-life situations over longer time periods; therefore, the time dimensions of perception and action in eating behaviour are not fully understood. These patterns in perceptions and their intensities (wanting and liking of food) might be important for understanding mechanisms in obesity and its treatment. In this thesis we are aiming to targeting those gaps in knowledge by a field-studies which might therefore add valuable information and confirmation to tradition lab-based and questionnaires studies that have limited design and techniques. Consequently, a new method in measuring the "wanting" and " liking" is aimed to be developed to measure these hedonic rewards components in real-life scenario. Finally, we are aiming to investigate the influence of exercise on these components in sedentary, lean and overweight individuals. Therefore, firstly in Study l we have developed and piloting the "Mind Eating" smart phone application to record and score 'wanting' and' liking' events under real life conditions. This application could function on both operating systems IOS/Androids and available for the research in Apple and google store. This application designed to be simple and easily used with a connected online database to revealed the data at any time by the researchers. A pilot study design in chapter 2 was aimed to examine the functionality and performance of the developed phone application according to the design specifications. Twenty two participants (lean n=l 7, overweight/obese n=S) were recruited from Bangor university staff and students. The smart phone application (Mind Eating) was used to track of participants 'wanting' and ' liking' of food and drink. The pilot study resulted into enhance some text interface of the application, reducing the period time of the experiment from 4 to 2 weeks and fix some capability of the the application to perform without network existence. Then in Study 2, "Mind Eating" application was utilised to gain a deeper insight into the psychological drivers of overweight and obese individuals. We aimed to analyse continuous patterns of 'wanting' and ' liking' of food in real life situations. We compared high body fat percentage (H-Fat) individuals with low body fat percentage (L-Fat). The following variables were measured: ' wanting' leading to eating events (WE), 'wanting' that did not lead to eating ('wanting' but resisting events, WR) and ' liking' after eating events (L). First part of the results which was an aggregate data analysis, revealed that the L-Fat group recorded significantly more food ' wanting' and eating events than did the H-Fat group. Both groups showed similar patterns for WE, WR, and L, but these scores differed significantly only within the L-Fat group. A strong trend (p = .052) towards higher L scores was found only in the L-Fat group but the two groups did not differ significantly in WE or WR. A Second part of the result was the (Time series analysis), this study was the first to analyse time series data on eating behaviour. Both groups showed a similar periodicity in unsuccessful and successful 'wanting' throughout the day. The ' liking' vector for the L-Fat group remained constant for the rest of the day following the morning meal. In contrast, the vector of 'liking' for the H-Fat group disappeared over the
same time period. The disappearance of periodicity in 'liking'-but not in 'wanting'-in H-Fat individuals means that 'wanting' and 'liking' are not linked or coupled in this population. This suggests that reward processing in the brains of overweight/obese individuals is not same as in lean people and may be dysfunctional. xii Finally, in Study 3, we investigated the effect of a single bout of exercise on the 'wanting' and ' liking' of food and drink in lean and overweight sedentary individuals. Participant (N= 18, lean n=8, overweight n= 10) randomized in in a repeated measures crossover type design study with an exercise and control trial and full randomized order of trials. Food Craving Questionnaires-Trait (FCQ-T) was administered as a baseline test and the Food Craving Questionnaires-State (FCQ-S) was measured during both experimental trials at three time points; immediately before (Pre), immediately post (Post) and 1 hr post (1 Hr) exercise. The "Mind Eating" application was used to measure participants 'wanting' and 'liking' of food and drink, 24 hours before and 24 hours after both trials. Exercise changed the scores for the physiological and psychological dimensions of eating behaviour in both groups. In the overweight group, exercise reduced the perception of ' wanting' and meal frequency, and suppressed the intense desire eat. To conclude, " Mind Eating" Phone application could offer for future a new approach in measuring the patterns in perceptions and their intensities (wanting and liking of food). Our data collected in free-living condition with a novel smart phone application could be interpreted as a strong support for reward deficiency in overweight/obese people while several observations point towards a more complex problem with involvement of enhanced craving contribution for wanting without integrating former consummatory reward information into the reward expectation. Finally, overweight individuals are shown to be more influenced by hedonic drivers of eating behaviour than are lean individuals. This could explain differences in anthropometric characteristics and the response to exercise for two groups.