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The short-term effects of exercise on appetite and ad libitum energy intake have received considerable interest as a potential strategy to reduce the prevalence of obesity over the past two decades. The experiments in this thesis have further investigated this topic by examining the appetite and the ad libitum energy intake responses in anticipation of an acute bout of aerobic exercise session. To achieve this, healthy, regularly active males and females (M= 55; F= 34; mean ± SD: age 24± 5 years; BMI 23.4± 3.2kg/m2) were recruited into four studies. The aim of the experiments in this thesis was to focus on the behavioural aspects of appetite and energy intake,and therefore, gut hormone responses were not investigated. In Chapter IV, a hypothetical exercise scenario (i.e. 60 minute hard aerobic exercise session) prompted a ~24% increase in the planned energy intake as opposed to a hypothetical rest scenario in regular exercisers. In Chapter V, we further demonstrated that anticipation of an aerobic exercise session (30 minutes cycling at 75% HR-max; 30 minutes running at 80% HRmax) led to an increase in planned energy intake for breakfast compared to a resting control trial. However, differences in planned energy intake did not result in any differences in the actual ad-libitum energy intake in the post-exercise or rest period. Chapter VI revealed a novel and a reproducible method to measure evening energy intake with a food pack that contained preweighed food items. This method was then employed for the following two chapters to measure evening food intake. Chapter VII investigated the effect of a planned 60 minute late-afternoon aerobic exercise session on appetite and energy intake both before (i.e. at breakfast and lunch) and after (i.e. over the evening) exercise compared to an identical resting control trial. The results indicated that a partial compensation (~11% increase in energy intake at lunch in the exercise trial) takes place during the preceding meal in response to a planned exercise session. However, this increase in energy intake at lunch was not sufficient to offset the energy deficit created by the exercise session, and therefore, still resulted in a negative energy balance (EB) in the short-term. Finally, Chapter VIII showed that this compensatory behaviour is still apparent in the preceding 24 hours and resulted in a ~10% increase in energy intake when compared to a resting control in anticipation of an aerobic exercise session, although this compensatory increase was still not sufficient to offset the energy deficit created by the exercise. Taken together, this thesis has shown that ad-libitum energy intake is affected by the anticipation of an aerobic exercise session. Moreover, although this compensatory increase in energy intake is not sufficient to offset the energy deficit created by the exercise session, it furthers our understanding of the effects of exercise on eating behaviour and the need for an explicit study design to explore the effects of exercise on appetite and energy intake in a laboratory setting. The results from this thesis can partially explain the discrepancies observed with the long-term exercise intervention studies that report less than expected amounts of weight loss.

Breakfast, which is typically consumed within 2-3 hours after waking up, is considered by many to be the most important meal of the day. Its carbohydrate (CHO) content ranges between 50-60% of its energy, meaning breakfast could replenish carbohydrate (glycogen) stores after a long overnight fast. A number of studies have shown the detrimental effect of omitting breakfast on endurance exercise, however, little is known about the effects on resistance exercise. Considering the prevalence of omitting breakfast among exercisers, commonly due to logistical/practical reasons, examining breakfast consumption versus omission on resistance exercise performance is of particular interest. To initially investigate this, the study reported in Chapter 3 compared performance in 4 sets to failure of back-squat and bench press at 90% of 10 repetition maximum (10-RM), between an ecologically valid breakfast (BC), containing 1.5 g carbohydrate/kg body mass, and a water only breakfast (BO). As hypothesised, total repetitions of back squat and bench press were less during BO compared to BC. Correspondingly, hunger was elevated, whilst fullness was decreased in the BC condition. These results demonstrate that omission of a pre-exercise breakfast might impair resistance exercise performance. However, it cannot be discounted that, as subjects were aware of when they were consuming breakfast or not, that the exercise performance responses were confounded by psychological factors (i.e. placebo/nocebo effects). Therefore, a double-blind study was conducted (Chapter 4), with the aim to compare resistance exercise performance after consuming a water only control breakfast (WAT) or two identical semi-solid breakfasts, one a virtually energy-free placebo (PLA), the other containing 1.5 g carbohydrate/kg body mass (CHO). CHO and PLA breakfasts were eaten with a spoon from a bowl and contained 4.25 mL/kg body mass water, 0.75 mL/kg body mass sugar-free orange squash and 0.1 g/kg body mass xanthan gum as a thickener, with addition of 1.5 g/kg body mass of maltodextrin in the CHO breakfast. Back-squat total repetitions were greater in both CHO and PLA compared to WAT. Correspondingly, CHO and PLA similarly suppressed hunger and increased fullness relative to WAT. This study indicated that breakfast likely exerted its effect on resistance exercise performance via a psychological effect. However, when higher volume resistance exercise was applied (Chapter 5), consisting of sets of 10 repetitions of leg extension to exhaustion at 80% 10-RM, an ergogenic role of carbohydrate was evident, as CHO produced greater total repetitions compared to PLA. Whilst the studies in Chapter 3 and 4 suggested that breakfast influenced performance via a psychological effect, appetite also responded correspondingly, raising the question as to whether appetite might influence resistance exercise performance. In a follow-up study (Chapter 6) two breakfasts containing 1.5 g carbohydrate/kg body mass were provided, but one included 0.1 g/kg body mass of xanthan gum (SEM), whilst the other did not (LIQ), with the aim of manipulating appetite without affecting carbohydrate intake. Interestingly, back squat total repetitions were greater following the SEM compared to LIQ and this correspond with decreased hunger and increased fullness in SEM compared to LIQ. In conclusion, the results from these experiments demonstrate that the perception of breakfast consumption, rather than carbohydrate/energy per se, improves resistance exercise performance. The ergogenic role of pre-exercise carbohydrate only seems to benefit extremely high-volume resistance exercise performance. Whether these effects are still apparent when pre-breakfast/meal glycogen stores are not optimal is unknown (i.e. if a not fully replaced from a previous training session). However, when subjects are well-fed, high-intensity intermittent exercise like resistance exercise might be influenced by sensation of fullness and a pre-exercise meal might exert its effects through this novel mechanism. In situations where the amount carbohydrate or the metabolic effects of the carbohydrate consumed before exercise are unlikely to influence performance (such as resistance exercise), consumption of meals that decrease sensations of hunger might be a simple strategy to enhance performance.

Fluid intake and regulation are implicated in the control of energy balance and appetite. The studies in this thesis have examined the effects of fluid manipulation on appetite and energy intake. Fifty-eight young, predominantly Caucasian males were recruited to five studies. The age, height and body mass of the subjects were: 24.9 ± 3.8 y, 1.79 ± 0.1 m, 80.1 ± 14.8 kg (mean ± SD) respectively. In Chapter 3, 13 h of hypohydration after exercise in the heat did not influence energy intake at an ad-libitum buffet meal (P=0.436) compared to a euhydrated trial, although greater thirst (P < 0.001) and lower fullness (P < 0.01) was reported in the hypohydration trial. Chapter 4 demonstrated that there was no difference in energy intake or appetite after 24 h of hypohydration either with or without fluid during a semi-solid ad-libitum breakfast. Thirst and fluid intake were greater during the hypohydrated with fluid (HYPO-F; 618 (251) mL) than the euhydrated with fluid (EU-F; 400 (247) mL) trials (P < 0.01). Chapter 5 and 6 showed that a bolus of water (500 mL) immediately before an ad-libitum porridge breakfast reduced energy intake in both healthy and overweight and obese subjects (P < 0.001). The water preload increased fullness and decreased hunger compared to pre-trial in both studies (P < 0.001). In Chapter 7, 75 minutes before an ad-libitum lunch a post-exercise milk (MILK) based drink reduced energy intake (6746 (2035) kJ) compared to an isoenergetic flavoured carbohydrate (CHO) and water based drink (7762 (1921) kJ; 7672 (2005) kJ) (P < 0.05). This thesis has shown that when subjects are hypohydrated, either after exercise or after 24 h of fluid restriction energy intake is not different at an ad-libitum meal. However, there is an increased thirst and subsequent fluid intake before an ad-libitum meal (chapter 3 and 4). This effect was more acutely displayed when a bolus of water was provided immediately before an ad-libitum breakfast meal and subsequently decreased energy intake in both normal and overweight/ obese subjects (chapter 5 and 6). The possible mechanism for this was gastric fill and distension creating satiety before a meal. Chapter 7 has showed that when subjects consume isoenergetic drinks with different energy densities (milk vs CHO and water), before an ad-libitum lunch, energy intake was decreased when milk was consumed. Milk having an increased energy density due to larger protein fractions (casein) may further explain the decrease in energy intake found in chapters 5 and 6 by a similar mechanism. Therefore, gastric fill before a meal decreases ad-libitum energy intake by either the intake of water immediately before a meal or by milk as a more delayed response (75 min). The hydration status however, did not affect energy intake directly in our finding, although it did affect subsequent fluid ingestion, which may have affected findings in chapters 3 and 4.

This thesis investigates self-tracking practices of users of MyFitnessPal calorie counting app. The thesis researches everyday self-trackers users who have started using the app on their own and are not part of any self-tracking community and focuses on the practices of self-tracking. The thesis responds to the literature on self-tracking that has often neglected everyday self-trackers and practices of self-tracking. First, many studies, whether sociological investigations or human-computer interaction research, focus on members of Quantified Self (QS) community (Choe, Lee, Lee, Pratt, & Kientz, 2014; Li, Dey, & Forlizzi, 2010; Neff & Nafus, 2015; Sharon & Zandbergen, 2016). QS is a community of individuals who are interested in learning more about themselves through, oftentimes unusual and complex, self-tracking, which involves modification of existing technologies or even creation of new ones. Thus, focusing on QS members neglects the individual everyday self-trackers, their experiences and practices. Second, existing studies have mainly focused on health or social implications of self-tracking (Lupton, 2012b, 2013d, 2014a, Swan, 2012b, 2013). These include, but are not limited to, potential of self-tracking to assist diagnosis (Wile, Ranawaya, & Kiss, 2014), or behaviour change (Chiauzzi, Rodarte, & Dasmahapatra, 2015), self-tracking increasing surveillance, public pedagogy (Rich & Miah, 2014) and subjection to neoliberal values and promotion of healthism (Lupton, 2012b, 2013a) or leading to monetisation of exercise (Till, 2014). While these studies have yielded important insights, they do not help us to understand what people actually do when they self-track, i.e. what practices self-tracking involves and how people engaged in self-tracking manage them. Guided by the STS approach that highlights the importance of observing the mundane practices and need to focus on technology users, this thesis explores the practices of everyday self-trackers. The exploration of the practices of self-tracking among the everyday self-trackers is based on 31 interviews with early mid-life individuals, who were mainly recruited from gyms and shared their self-tracking experience of using the MyFitnessPal calorie counting app. The analytical chapters answer three questions: What is self-tracking by calorie counting in the everyday like? How is self-tracking by calorie counting done? What are the practices through which self-tracking affects those engaged in it? To answer the first question, I juxtapose self-tracking goals, use and effects as they are represented in the literature on the QS to those of my participants. Doing this reveals that self-tracking in the everyday is perceived and done quite differently than the QS metaphor would allow us to believe. The goals of the participants are mundane (weight loss), they do not use the sophisticated features of the app and are not interested in the historical data, the effects of the app are not life-changing and temporary closely tied to the use of the app. This stands in contrast to QS metaphor where self-tracking is geared towards continuous self-improvement, driven by intricate data analysis and biohacking. To answer the second question, I focus on self-tracking by calorie counting with MyFitnessPal as a dieting practice. I explore how self-tracking affects the daily practices as well as is incorporated in participants lives. The users, thus, aim to find an approach to temporal aspects of tracking and precision that would fit most conveniently with their other daily practices. They manipulate their use of the app to accommodate any meals that are not in their usual dieting routine. This highlights that dieting through self-tracking is not a straightforward data collection and involves practical strategies and negotiations, and can both influence and be influenced by other everyday practices. The third question focuses on quantification, that is the production and communication of numbers (W. N. Espeland & Stevens, 2008, p. 402). Quantification has usually been discussed at institutional levels, in terms of government, science or, in the case of Espeland and Sauder s (W. N. Espeland & Sauder, 2007) seminal work, in terms of academic rankings. I adopt the insights from these studies to make sense of the quantification at the individual level using MyFitnessPal. I draw out two features of individual quantification that distinguish it from institutional one, mainly that quantification is done for oneself only and it relies on self-governance. Further, I outline how quantification affects such decisions as whether to eat, what to eat and how much to eat. Quantification also works as commensuration as participants compared different foods referring to their calorie value. However, unlike in the case of institutional quantification, individual quantification did not have to be accepted unquestionably and often other values of food would be weighted in relation to calories when participants made choices what to eat. Ultimately, this thesis contributes a new perspective on self-tracking as it explores the mundanity of it. It adds fine-grained insights into the everyday practices of self-tracking by adopting a novel analytical angle that centres on practices and by exploring a neglected user group of everyday self-trackers.

The main aim of this thesis was to increase our understanding of the metabolic responses associated with short-term high-fat overfeeding. To this end, four separate studies are described in this thesis; each of which involved the provision of a high-fat, high-energy diet to young, healthy, lean individuals. The first of these experimental chapters (Chapter 2) determined the effects of a 7-day, high-fat (65%), high-energy (+50%) diet on postprandial metabolic and endocrine responses to a mixed meal challenge. This chapter demonstrates that 7-days of overfeeding impaired glycaemic control in our subject cohort but did not influence the response of selected gut hormones (acylated ghrelin, GLP-1 and GIP). In a mechanistic follow up study utilising stable isotope tracer methodology we then demonstrate that overfeeding-induced impairments in glycaemic control are attributable to subtle alterations in plasma glucose flux, rather than the overt tissue-specific adaptations (e.g. increased EGP, or reduced glucose disposal) that have previously been reported (Chapter 3). In an attempt to delineate the time-course of diet-induced impairments in glycaemic control, we then investigated the effects of 1-day of overfeeding (+80% energy with 73% of total energy coming as fat) (Chapter 4). Results demonstrate that a single day of overfeeding elicits responses which are comparable to 7-days of high-fat overfeeding; highlighting the rapidity with which excessive high-fat food intake can negatively influence glucose metabolism. In chapter 5 we utilised stable isotope tracer and muscle biopsy techniques to demonstrate that 7-days of high-fat overfeeding impairs glycaemic control but does not influence the fed-state mixed muscle protein fractional synthesis rate (FSR). In conclusion, the findings of this thesis demonstrate that while short-term high-fat overfeeding negatively influences whole-body glucose metabolism, skeletal muscle protein metabolism appears to be relatively unaffected in young, lean, healthy humans.

Background and Aims Many low- and middle-income countries are undergoing epidemiological and health transitions. South Africa has one of the highest prevalences of overweight and obesity in Sub-Saharan Africa. This research examined neighbourhood and household socio-economic influences on the risk of overweight and obesity in terms of anthropometric status and dietary intake among urban South African adolescents. A further aim was to conduct a qualitative study on the potential for religious groups such as Churches to be used as community-based organisations for obesity intervention. Methods A secondary analysis of neighbourhood and household socio-economic status (SES), anthropometric and dietary data was carried out on adolescents aged 17-19 years from the Birth to Twenty Plus cohort study in Johannesburg-Soweto. Qualitative data were collected through focus groups discussions and a community readiness survey with church leaders. Results No significant associations were observed between SES (household and neighbourhood) and energy, protein, fat, or carbohydrate intakes in males. Some significant associations were found between SES and dietary intake in females. Females had a higher prevalence of overweight and obesity than males (26.2% vs. 8.2%, p<0.0001). In males, poor household SES was associated with lower odds of overweight, fatness and high waist-to-height ratio (WHTR). For females, household SES was not significantly associated with overweight, fatness and high WHTR. The qualitative research showed that there was a very low level of community readiness among church leaders for obesity prevention programmes. Conclusions The dietary results suggest that the diet of these adolescents is transitioning to that seen in high income countries. It also highlights that even within the same relatively small urban area, nutrition transition does not affect different groups in uniform ways. The qualitative results indicate that programmes should focus around raising awareness of the problem of overweight/obesity in this community.

Currently there is limited research addressing the eating behaviours of preadolescent children, despite evidence suggesting that friends and peers may contribute to the developing eating attitudes and behaviours of children of this age. Eating behaviours in terms of this thesis include both under- and over- eating behaviours, with a specific focus on the under-eating behaviour, dietary restraint, and the over-eating behaviours emotional eating and external eating. The fundamental aim of this thesis was to examine friend and peer influences on children s eating behaviours, with a specific focus on a community sample of preadolescent children. Based on links established in the literature between childhood eating behaviours (dietary restraint, emotional eating and external eating) and parental controlling feeding practices (pressure to eat and restriction) and childhood symptoms of anxiety and depression, these factors were also considered alongside the contribution of friends and peers, both cross-sectionally and longitudinally. The longitudinal stability and continuity of self-reported eating behaviours and perceived parental feeding practices in preadolescent children were also examined in this thesis. A pilot study and experimental study provided an objective measure of children s snack food intake following a school lunchtime, when offered a selection (healthy and unhealthy) of snack foods in the presence of friends and peers. Links between food intake in the presence of friends and peers, and self-reported eating behaviours, parental controlling feeding practices, child symptoms of anxiety and depression and BMI were further explored. The research in this thesis suggests that friends dieting behaviours predict individual children s dieting behaviours, and also highlights links between problematic eating and anxiety in preadolescent children. Parental controlling feeding practices were found to have a negative impact on preadolescents eating behaviours and were also found to be potentially linked to the development or maintenance of anxiety and depression symptoms in children of this age. Preadolescents reports of eating behaviours and perceptions of the controlling feeding practices their parents utilised with them were stable over time, but, with the exception of restriction, lacked continuity. Dietary restraint, emotional eating and external eating decreased over a 12 month period. While some of the research in this thesis requires replication, the results present many novel and interesting findings. Using longitudinal and experimental data, the research reported on in this thesis highlights the important contributions of friends, peers, parents and individual anxiety and low mood to the eating attitudes and behaviours of preadolescent aged children.

The emergence of obesity as a distinct disease could have far reaching consequences for an organisation where optimum health and physical fitness are required for personnel to perform their occupational roles effectively. The aim of this thesis is to increase our understanding of the prevalence, correlates and predictors of obesity in the British Army. Systematic review indicated a smaller body of knowledge in respect of the treatment and correlates of obesity in military populations. Successful treatment interventions incorporated exercise, healthy eating information, behavioural modification, self-monitoring, relapse prevention, structured follow-up and were supported by trained personnel. The major significant correlates of obesity were being enlisted personnel, male, ≥35 years of age, African-American/Hispanic ethnicity, and married (with spouse present). The review highlighted the deficit in knowledge concerning treatment, and correlates of obesity in military populations. The trend of escalating obesity has prompted some armed forces to report obesity trends and prevalence, the findings of which suggest that obesity is a growing concern in the armed services. A study based on the secondary analysis of data covering 50,000 British Army soldiers indicated that according to BMI, 56.7% of the study population were overweight and of those individuals 12% were obese. When waist circumference data were added to the BMI data, the results indicate that females displayed a higher percentage of risk of obesity related ill-health (a combination of BMI and waist circumference) than males (30.4% and 24% respectively). Further analysis suggested that age, marital status, rank and military employment category were significant correlates of obesity. Additionally, obesity and increased risk of obesity related-ill-health were linked to higher failure and lower attendance on British Army physical tests. Data suggested older army personnel (>30) had a higher pass rate, but a lower attendance rate. The final analysis of all available variables suggested physical test outcome, age, medical status and enlisted status were the most significant predictors of obesity. A final study based on a different study population (n=1124) from the high readiness component of the UK based British Army sought to identify relationships between health behaviours that were not supportive of healthy weight and to understand the predictive influence of individual and collective behaviour in relation to obesity and the risk of obesity related ill-health in military personnel. The investigation used a health behaviour questionnaire to assess health behaviours that might influence weight status. Final analysis of this highly active population suggested, restrained eating, food preparation in the working week, injury status, age, sedentary behaviour, leisure-time physical activity engagement and type of motivation for exercise were the most significant factors. This thesis highlights the lack of knowledge, and gives evidence to support the impact of obesity on individual health and collective occupational capability. Obesity is a complex multifaceted disease where no single causal route predominates. However, the identification of potential causal and predictive relationships will aid in the prevention and treatment of obesity in the British Army.

Background. The Maya are one of the largest Mesoamerican groups. The decline of the classic Maya society, the subsequent Colonial domination and the current national economic policies has had a severe biological and social impact on the Maya across several generations. Accumulated evidence suggests that conditions and environments experienced by one generation can affect the health, growth and development of the next generation (Emanuel, 1986). Historical evidence of political, educational and socioeconomic deprivation suffered by the Maya from Yucatan, Mexico, provides us with the opportunity to test the intergenerational influence hypothesis and ascertain the impact of the biosocial background of urban Maya grandmothers (first generation) and mothers (second generation) on the growth and nutritional status of their children (third generation). Aims. The main objective is to assess the impact of socioeconomic and intergenerational factors on the growth of Maya children, in a sample of children, their mothers and maternal grandmothers. The specific objectives are: 1) to assess the nutritional status and nutritional dual burden prevalence in participants, 2) to identify the pre and postnatal biosocial and economic factors that relate to the nutritional status of the children, and 3) to assess the intergenerational influences on the growth of participants: from grandmothers to mothers and from grandmothers and mothers to children. Methods. The sample is composed of 109 triads of Maya children (6-8 years old), their mothers and their maternal grandmothers from the city of Merida, Yucatan, Mexico. From September 2011 to June 2012 we collected anthropometric, body composition and socioeconomic data on the three generations. We also assessed parameters about living conditions of maternal and grand-maternal childhood. Nutritional status was assessed by comparing the participants against the Comprehensive Growth References published by Frisancho (2008) and based on the NHANES III. Pre and postnatal biosocial and economic factors were analysed through multiple regression models. Intergenerational influences were assessed through: 1) bivariate and partial correlations in anthropometric and derived variables between participants, 2) path analysis to identify the direction and magnitude of direct and indirect causal effects between the three generations, and 3) multiple regression models to identify the effect of anthropometric and socioeconomic intergenerational factors on the growth of mothers and children. Results. Eleven percent of the children were categorized as stunted and 36% met the criteria of risk for abdominal obesity. Only 1% of children exhibited the combination of stunting and abdominal obesity. Mothers and grandmothers showed very low average heights and high levels of abdominal obesity. The combination of maternal abdominal obesity and child stunting was present in the 6% of mother-child dyads. It was found that preeclampsia and cigarette smoke exposure during pregnancy and household overcrowding impacted negatively the linear growth of the children. Maternal education and the presence of grandmothers at home predicted healthier values of BMI, waist circumference, body fat and body lean mass percentages on children. Maternal height and leg length (LL = height sitting height) were positively associated with the linear growth of children. These associations were not modified by the grand-maternal size, in terms of very short stature. In contrast, associations in weight, body mass index, sum of skinfolds and fat mass were stronger in grandmother-child pairs than in mother-child pairs. The birth weight of the children was positively associated with maternal head circumference and negatively associated with the absence of a toilet at home during maternal childhood (i.e. when the mother was growing up). Grand-maternal intergenerational predictors of children s height, leg length, body mass index, waist circumference and skinfolds were: index of household characteristics, family size and school attendance during childhood. Family size and paternal job loss during maternal childhood were the maternal intergenerational factors that influenced significantly the body mass index, waist circumference and skinfolds of children. Conclusions. Growth and nutritional status of the children, mothers and grandmothers reflect the effects of chronic deprivation and poverty that are a constant among the Maya in the Yucatan. Under and-overnutrition coexisted in this sample of three generations. Pre-and-postnatal biosocial and economic factors impacted the growth and nutritional status of children. Harsh living conditions experienced by mothers and grandmothers during their childhood influenced the prenatal and postnatal growth of children. We suggest that disadvantaged conditions experienced by mothers and grandmothers during their first years of life impacted their own growth and this in turn is influencing the growth of children of the third generation. Substantial reductions in poverty levels and increase educational levels of the mothers are required to overcome the intergenerational traces on the future generations.

Lifestyle choices threaten to compromise health and performance of trained athletes. This thesis presents a series of studies which broadly investigated the impact of nutritional and physical challenges to human health and performance. The potential causes and effects of fluid imbalances on physical health, immune function and athletic performance were investigated. Certain populations experience chronic low-level hypohydration and athletes often fail to rehydrate sufficiently between exercise sessions. The long-term implications of hypohydration are not fully understood, but are suggested to be associated with chronic disease. In this thesis, maintenance of fluid balance was observed in healthy males, despite a caffeine intervention thought to cause diuresis. Furthermore, when mild hypohydration was induced by 24-h fluid restriction, there was little impact on mucosal immunity during endurance exercise compared with euhydration. The impact of intensified training (IT) on the physical, mental, hormonal and immunological status of well-trained athletes was investigated. A performance-specific nutritional intervention was implemented to investigate the effects of nutrient availability during prolonged exercise training sessions. Phases of IT are a regular feature of a periodised training programme. However, an imbalance between training and recovery can have significant implications for long-term athletic performance and general wellbeing. Changes in neuroendocrine, neurobiological and mucosal immune function were observed during IT and some potential markers of overreaching and were identified. Further research is required before practical application of these markers can be used effectively in the field. A relatively short period of IT resulted in significant disruptions to mood state and sleep quality. Minor changes in exercise performance were observed. Markers of overreaching were highly individual, as were responses to training.

At present, the process of parental modelling of eating behaviours and attitudes has received limited research interest. While often mentioned as a possible factor in relation to child feeding and the development of eating behaviours, only a few studies have explicitly researched parental modelling. The main aims of this thesis were to develop a new measure to assess modelling multidimensionally and to explore the relationships between parental modelling of eating behaviours with a variety of parent and child factors. Initially, a parental self-report measure (the Parental Modelling of Eating Behaviours Scale; PARM) was developed, validated and piloted as part of a series of studies exploring the associations between modelling and a range of self-reported parental and child factors. To provide further validation for the PARM, an observational coding scheme was developed, based on the newly developed modelling measure, and this was utilised in two further studies which looked at self-reported and observed parent and child factors. The key findings from this thesis suggest a number of beneficial relationships. For example, maternal modelling was positively correlated with healthy food intake in both mothers and their children. In addition, both maternal and paternal modelling were associated with children s increased enjoyment of food and lower levels of food fussiness. Observations of maternal modelling were also found to be positively related to other observed adaptive, non-directive feeding practices, such as encouragement to eat. However, less positive relationships were also identified, with modelling being related to parents mental health symptoms and to unhealthy food intake in both mothers and their children. In conclusion, this thesis has identified three distinct facets of modelling and highlighted factors which might be linked to parental role modelling around eating behaviours. While much of the research within this thesis is exploratory, and the findings require replication, they would suggest that parental modelling has the potential to positively influence children s eating behaviours. However, parents should also be made aware of the potential detrimental effect that modelling less adaptive eating behaviours may have on their children s food intake, particularly those eating behaviours that parents may be unaware of modelling.

Overweight and obesity prevention efforts focused on pre-adolescent girls are justified because the health of future mothers can significantly impact the health of their future offspring. Aims and Objectives: This thesis aimed to investigate the role of community readiness in the prevention of overweight and obesity in pre-adolescent girls within the Charnwood Borough (Leicestershire) community. Specifically the objectives of this research were to: 1) further the understanding of the concept of community , 2) identify, using focus groups, the key informants and other ecological influences acting on pre-adolescent girls health behaviours, 3) employ the Community Readiness Model (CRM), using key informant interviews, to assess the Charnwood Borough community s knowledge, awareness and readiness to adopt behaviours associated with the prevention of overweight and obesity in pre-adolescent girls, 4) evaluate the usefulness of the CRM for this task and 5) form recommendations for a tailored intervention. Methods: This research used focus groups with pre-adolescent girls to identify the key informants who influence their lifestyle choices regarding dietary and physical activity behaviours. The study recruited 56 female participants aged between 6-11 years from 8 primary schools. In total 13 focus groups with between 2 to 7 participants per group were performed. To assess the level of community readiness, 33 key informants identified as informing the health behaviours of pre-adolescent girls were recruited. Semi-structured interviews followed an adapted version of the CRM. The model consists of six dimensions: community efforts; community knowledge of efforts; leadership; community climate; community knowledge of the issue and resources which are scored on a scale of 1 (no awareness) to 9 (high level of community readiness). The average of these scores is the community readiness stage. Findings: In relation to the first objective, the definition of a community given by those residing in the Charnwood Borough community included: people and groups of people (e.g. school; religious and parents community groups); characteristics (i.e. geographical area; where people reside; buildings; institutions and the size of the community); sense of belonging and the attempt to improve the community for its members. By valuing the perspectives of pre-adolescent girls, a deepened understanding of the broad range of key informants (Dinner staff, Doctors and dentists, Head teachers, Girl Guide leaders, Government, Grandparents, Neighbours, Parents, Peer group, School cooks, Shop keepers, Siblings, Sports Coaches and Teachers) acting on their health behaviours was achieved (Objective 2). The community readiness score relating to healthy eating and drinking corresponded to the Preparation Stage (Objective 3), whereby influential community members have begun planning efforts by deciding what to do and who will do it and the community offers modest support of efforts promoting healthy dietary behaviours. The community readiness score for physical activity was higher corresponding to the Initiation Stage where there is enough information available to justify efforts and activities are underway to support healthy physical activity behaviours. Qualitatively, the key findings from applying the CRM are that: the effectiveness of community initiatives promoting healthy behaviours can be improved; there are varying levels of concern and awareness regarding unhealthy behaviours and child weight status in the community; social disparities are perceived to exist in community health behaviours; communication between schools and parents are seen as important for the success of school policies; parental attitudes and behaviours inform child behaviours; enjoyment is an important predictor of girls activity levels and aspects of the Charnwood Borough's environment do not support healthy behaviours. The CRM was shown to be an appropriate tool for assessing community readiness (Objective 4) providing the qualitative strengths of the model are emphasised. The community readiness score and the qualitative analysis informed the recommendations for an intervention in the Charnwood Borough (Objective 5). Key aspects of these recommendations include: raising the community s awareness of pre-adolescent girls health behaviours; ensuring all initiatives are accessible and appealing to low income families by working directly with these groups; fostering a greater sense of community through increased community cohesion and social interaction; placing social interaction and enjoyment at the centre of all activities, and attempting to make the healthier option the easier choice through modifications to the environment. Conclusions This thesis is the first to apply the Community Readiness Model to the prevention of overweight and obesity in pre-adolescent girls in the UK and has demonstrated the value of applying a community readiness assessment prior to the implementation of interventions.

Background Middle-income countries are currently undergoing nutrition transition more rapidly than did high income countries. These populations are therefore at high risk of over-nutrition (obesity) and nutrition-related, non-communicable diseases before the elimination of under-nutrition and infectious diseases. Such nutritional double burden is most common in low SES groups of middle-income countries, such as the Maya of Mexico. Long-term poor environmental conditions during early life results in a population with high levels of chronic under-nutrition (stunting), and a consequent predisposition toward overweight/ obesity, and associated health risks later in life. It is important to be able to identify individuals at an increased risk of diseases related to double burden and to determine whether stunting impacts the ability to identify at risk individuals. Aims The overall purpose of this doctoral research was to examine double burden in the urban Maya, a low SES section of the Mexican population which is a current example of a population undergoing significant transition. The specific aims of this thesis were fourfold: 1) To describe the living conditions and population characteristics of the urban Maya of southern Merida in the spring and summer of 2010; 2) to determine whether body mass index (BMI) predicts adiposity indicators in a sample of women and children with a high prevalence of stunting, 3) to determine whether measures of linear growth in women can be predicted by their recalled childhood environment and 4) To determine whether the relationship between objectively estimated free-living energy expenditure and body composition is altered by stunting. Methods Data from interviews, anthropometric measurements and bioelectrical impedance analysis were collected on 58 Maya schoolchildren aged 7-9 years-old and their mothers living in the south of Merida, Mexico. Objective, free-living physical activity monitoring using combined accelerometry and heart rate monitoring of the children was also performed for one week. The interview data was used to describe the living conditions of the south of Merida. Whether stunting status or body proportions influenced the power of BMI to predict adiposity indicators was assessed for the mothers and the children. The mothers recalled early life SES was compared to their current measures of linear growth. The children s objectively estimated energy expenditure was compared to their body composition and measurements of body size. Results The Maya of southern Merida overall had access to clean drinking water and basic health care and have apparently eliminated acute under-nutrition. Yet they remained double burdened with simultaneous stunting and overweight/ obesity. Individual double burden levels were high, with 70% of the mothers were simultaneously stunted and overweight. Family level double burden was also high, with 28% of the families having an overweight mother and a stunted child. The rates of childhood malnutrition varied widely when using different cut-offs. Child stunting rates were between 15.5% and 37.9% when using -2 z-scores of Frisancho s Comprehensive (created using NHANES data) reference versus the 5th percentile of the WHO reference, respectively. Child overweight/ obesity rates were less than 10% when using weight-for-age on both the Comprehensive and WHO reference charts. Child overweight/ obesity as classified using BMI z-scores was between 27.5 to 34.5% using the Comprehensive and WHO reference, respectively, while child overfat was over 80% when using body fat percentage for age reference curves. BMI predicted adiposity indicators in these Maya children, explaining between 33 and 84% of the variance in arm fat index and waist circumference z-score, respectively. BMI was less strongly related to the mothers adiposity indicators, explaining between 19 and 70% of the variance in arm fat area and waist circumference. The relationship between BMI and adiposity indicators was unchanged by stunting or body proportions in either mothers or children. Mothers recalled early life SES was significantly related to but explained little of the variance in her measures of linear growth. Birth decade explained 5% of the variance in stature and the Modernisation index (urban/ rural birth, sugar sweetened beverage consumption, packaged food consumption) explained 5% of the variance in mothers leg length. Birth order, sibling number and consumer durable ownership were also significantly related to linear growth of the mothers. These Maya children had high levels of physical activity, as all exceeded the recommended 60 minutes of moderate-to-vigorous physical activity per day. After controlling for fat free mass, short stature did not predict lower resting energy expenditures in the children. However shorter stature did predict lower levels of activity energy expenditure, particularly in girls. Stunted girls had the lowest activity energy expenditures. Conclusions These urban Maya tend to have access to basic sanitation and services and are at a very high risk for NR-NCDs with the co-existence of chronic under-nutrition (stunting) and overweight/ obesity. The high rates of stunting do not impact the usefulness of BMI to estimate adiposity nor does stunting appear to impact children s energy expenditure. While BMI is useful to predict adiposity in these urban Maya children, it is not recommended for use in the mothers. Interventions to reduce childhood adiposity need to begin very early in life to most effectively reduce adiposity. Research into the low SES groups of middle-income countries, offers insight to what may occur in low-income countries as they advance in the nutrition transition.

Objectives. This study aimed to provide data on water intake from food and beverages of free-living adults in their natural environment, and investigate how this is affected by physiological, psychological, social and environmental factors. A further aim was to monitor the hydration status of free-living adults and relate this data to water intake. Methods The consumption of all food and beverages was recorded in a diary over three consecutive days by 80 healthy adults (40 males, 40 females), aged 18 to 65 years, who were instructed to continue their normal eating and drinking habits and lifestyles throughout the study. The data was analysed to determine total daily water intake and how this was affected by time of day, day of the week, presence of others, location of consumption, age and subjects mood. A further 20 healthy subjects (10 males, 10 females) repeated these procedures but also had blood samples taken for monitoring of blood indices (haemoglobin concentration, haematocrit, sodium concentration, and potassium concentration) and provided urine samples for the measurement of urine indices (volume, colour, specific gravity, osmolality and sodium, potassium, chloride, and creatinine concentrations). Results The total volume of water consumed by the 80 subjects was 2229  882 ml/day (mean  standard deviation). Females tended to consume more water than males (2402  827 ml/day vs 2056  911 ml/day, P = 0.079). Similar volumes were consumed by the additional 20 subjects in the hydration status study. Females appeared euhydrated; males appeared mild dehydrated, having a higher morning and 24-hour urine specific gravity and osmolality than females (P < 0.05, respectively). Conclusions The mean daily total volume of water consumed by females in this study was greater than the adequate intake value set by the European Food Safety Authority; for males it was lower. Females were euhydrated during the study but males tended to be mild dehydrated, reflecting their comparative water intakes.

Evidence supports increased fat oxidation during sub-maximal exercise, 3h following the ingestion of a low glycaemic index (LGI) carbohydrate (CHO) meal compared with high glycaemic index (HGI) carbohydrate meal. The meals contained the equivalent of 2g/kg body mass of available carbohydrate. The aim of this thesis was to investigate whether or not the increased fat oxidation following a low glycaemic index meal is evident in recreationally active participants following the ingestion of breakfast with an available carbohydrate content of 1g.kg-1 BM.

This thesis used fifty hours of naturally occurring video and audio taped data from the ‘weigh-in' section of four commercial weight management groups in the East Midlands of England. This thesis is a discursive psychological and conversation analytic investigation of the turn-taking organization of the talk, examining what the group leaders and members make relevant in their talk about food and dieting. The data was transcribed using the Jeffersonian method. Group members attend the group weekly, and are weighed - their weight gain, loss or maintenance is recorded on a membership card. The analytic chapters follow the format of the ‘weigh-in' section of the meeting exploring firstly how the group leaders and members manage the practices of getting ready to be weighed; then how the ‘news' of weight gain, loss or maintenance is told and receipted; before exploring how ‘advice-giving' is constructed and the final analytic chapter deals with the issues of morality and accountability in the leaders' and members' talk. Analysis shows that the ‘pre-weigh in practices' involved before the group members are weighed consists of two robust patterns, 1) the practice of getting undressed is not oriented to by either the group members or group leaders and the group leaders avoided direct eye contact and concerned themselves with other business or 2) when no undressing practices took place, the group leaders were much more comfortable with direct eye contact. These sequences show how the body and its practices are constructed in particular ways within, and as part of the practices of getting ready to be weighed. Analysis showed the telling and receipting of weight news gets done differently depending on whether the group members have gained, lost or maintained weight. When the news concerned weight gain, the sequence included a ‘pre-announcement' and the news TCU was punctuated with marked trouble. When the news concerned weight loss, only the group members produced a pre-account and the news TCU contained no marked trouble. Finally, when the group members had maintained weight, the news TCU was delivered bluntly, and there was no evidence of trouble. In relation to advice-giving, analysis showed that group members repeatedly worked to assert their epistemic priority to avoid having to acknowledge the advice and the advice was receipted minimally. Finally, analysis showed that group members produced accounts with reference to a moral evaluation, such as blame or culpability. Sometimes an account was produced to circumvent being held publicly accountable for the event or action. It became apparent that both the group leaders and group members could not orient to themselves, their behaviour or food without it being constructed within a moral or accountable framework. Therefore, the thesis is an exploration of how group leaders and members manage the ‘dieting-practices' involved in getting weighed in a commercial weight management group and how using DP and CA can show the intricate turn by turn organization of such practices.

Previous studies have suggested that brief exposure to the sight and smell of food can elicit a momentary increase in desire to eat that food and can stimulate food intake. This thesis sought to explore individual differences in this 'food-cue reactivity.' Specifically, it aimed to explore associations between reactivity to food cues and i) dietary restraint (Experiments 1 to 6), ii) dietary disinhibition (Experiments 1 to 6), iii) everyday portion-size selection (Experiments 3 to 5), iv) body weight (Experiments 5 and 6), v) sensitivity to reward (BAS trait) (Experiment 6), and vi) Impulsivity (Experiment 6) Using a typical cue reactivity paradigm, female students (Experiment 1 n = 56, Experiment 2 n= 120, Experiment 3 n = 30, Experiment 4 n = 30, Experiment 5, n = 120, Experiment 6 n = 120) from Loughborough University (aged between 18 and 30) were exposed to a food cue and then a series of subjective (appetite ratings), and behavioural (intake and desired portion size), markers of appetite were assessed Notably, two main findings emerged from this research. Firstly, there was little evidence to suggest that food-cue reactivity shared any association with dietary restraint status per se. Rather, sensitivity to reward, impulsivity, and dietary disinhibition, were identified as potentially important determinants of sensitivity to food cues. Secondly, some experiments (Experiments 3 and 5) suggested that foodcue reactivity might be elevated in individuals who are overweight, and who select larger everyday portion sizes. Based on these findings, conclusions are drawn regarding the potential mechanisms which might govern food-cue reactivity, and the possible consequences of greater reactivity for everyday food consumption. In particular, it is concluded that food-cue reactivity might result from a universal sensitivity to stimuli which predict the occurrence of a reward, and from an inability to exercIse sufficient self-control in the presence of tempting environmental cues. In addition to this, it is also suggested that, over time, a greater susceptibility to the effects of food cues might contribute to, greater everyday food intake, and weight gain. To move forward within this research area, studies should continue to investigate the role of food-cue reactivity in overeating, and seek to further identify the mechanisms which promote greater reactivity to these cues.