Biomedical subjects

Andrew J Hill

Publications and source records attributed to Andrew J Hill.

9 recordsLinked to original sources

PubMed2007

Long-term dietary compensation for added sugar: effects of supplementary sucrose drinks over a 4-week period.

The long-term physiological effects of refined carbohydrates on appetite and mood remain unclear. Reported effects when subjects are not blind may be due to expectations and have rarely been studied for more than 24 h. The present study compared the effects of supplementary soft drinks added to the diet over 4 weeks on dietary intake, mood and BMI in normal-weight women (n 133). Subjects were categorised as 'watchers' or 'non-watchers' of what they ate then received sucrose or artificially sweetened drinks (4 x 250 ml per d). Expectancies were varied by labelling drinks 'sugar' or 'diet' in a counter-balanced design. Sucrose supplements provided 1800 kJ per d and sweetener supplements provided 67 kJ per d. Food intake was measured with a 7 d diary and mood with ten single Likert scales. By 4 weeks, sucrose supplements significantly reduced total carbohydrate intake (F(1,129) = 53.81; P<0.001), fat (F(2,250) = 33.33; P<0.001) and protein intake (F(2,250) = 28.04; P<0-001) compared with sweetener supplements. Mean daily energy intake increased by just under 1000 kJ compared with baseline (t (67 df) = 3.82; P< 0.001) and was associated with a non-significant trend for those receiving sucrose to gain weight. There were no effects on appetite or mood. Neither dietary restraint status as measured by the Dutch Eating Behaviour Questionnaire nor the expectancy procedure had effects. Expectancies influenced mood only during baseline week. It is concluded that sucrose satiates, rather than stimulates, appetite or negative mood in normal-weight subjects.

Affect↗

PubMed2006

A TRPC-like non-selective cation current activated by alpha 1-adrenoceptors in rat mesenteric artery smooth muscle cells.

The TRPC family of non-selective cation channels has been suggested to play a key role in the responses to alpha1-adrenoceptor stimulation of vascular smooth muscle. However, there are still very few reports of non-selective cation currents activated by alpha1-AR in resistance arteries. Here, we examine the expression of TRPC channels and the currents activated by alpha1-adrenoceptors in rat mesenteric resistance artery smooth muscle. Messenger RNA and protein for TRPC1, TRPC3 and TRPC6 were detected within the arteries by RT-PCR and immunoblotting. Endothelial and adventitial layers were found to express the TRPC1, TRPC3 and TRPC6 proteins whereas only TRPC1 and TRPC6 were detected in the arterial smooth muscle by confocal immunofluorescence microscopy. In whole-cell patch-clamp recordings from isolated mesenteric arterial myocytes, an outwardly rectifying non-selective cation current was activated by both the alpha1-adrenoceptor agonist, phenylephrine (10 microM), and the diacylglycerol analogue, 1-oleoyl-2-acetyl-sn-glycerol (100 microM). Responses to 1-oleoyl-2-acetyl-sn-glycerol were not blocked, but increased, following inhibition of protein-kinase-C with either bisindolylmaleimide-I (1 microM) or chelerythrine (1 microM). The currents activated by both phenylephrine and 1-oleoyl-2-acetyl-sn-glycerol were inhibited by Gd3+ (100 microM) but potentiated by flufenamic acid (100 microM). Collectively, these findings demonstrate for the first time the expression of TRPC1 and TRPC6 in rat mesenteric artery smooth muscle and the existence in rat isolated mesenteric arterial myocytes of a TRPC-like non-selective cation current activated by alpha1-adrenoceptor stimulation and 1-oleoyl-2-acetyl-sn-glycerol.

Animals↗

PubMed2006

Motivation for eating behaviour in adolescent girls: the body beautiful.

Body dissatisfaction is commonplace for teenage girls and is associated with dieting and unhealthy weight-control behaviours. The idealisation and pursuit of thinness are seen as the main drivers of body dissatisfaction, with the media prominent in setting thin body ideals. Television and consumer magazine production in the UK are extensive, annually releasing 1x10(6) h programming and >3000 magazine titles. Their engagement by adolescent girls is high, and in surveys girls identify thin and revealing body images as influential to the appeal of thinness and their pursuit of dieting. Experimental studies show a short-term impact of these images on body dissatisfaction, especially in teenagers who are already concerned about body image. Magazine images appear more influential than television viewing. For many adolescents selecting thin-image media is purposive, permitting comparison of themselves with the models or celebrities featured. Indeed, the impact of the media needs to be understood within a social context, as engagement is often a highly-social process. Media influence is uneven because of differences in its content and manner of communication, and individual differences in vulnerability to its content. Greater social responsibility on the part of the media and better media literacy by children would be beneficial. For those working in adolescent nutrition it is a reminder that adolescent food choice and intake are subject to many competing, contradictory and non-health-related determinants.

Adolescent↗

PubMed2006

Obesity and risk of low self-esteem: a statewide survey of Australian children.

OBJECTIVE: There is variation in the psychological distress associated with child obesity. Low self-esteem, when observed, provides very little information about the nature of the distress and no indication of the proportion of obese children affected. This study used a domain approach to self-competence to evaluate self-esteem in a representative sample of Australian children. PARTICIPANTS AND METHODS: A total of 2813 children (mean age: 11.3 years) took part in the study. They were recruited from 55 schools and were all in the last 2 years of primary school. Participants completed the Self-perception Profile for Children, a measure of body shape perception, and their height and weight were measured. RESULTS: Obese children had significantly lower perceived athletic competence, physical appearance, and global self-worth than their normal weight peers. Obese girls scored lower in these domains than obese boys and also had reduced perceived social acceptance. Obese children were 2-4 times more likely than their normal weight peers to have low domain competence. In terms of prevalence, 1 of 3 obese boys and 2 of 3 obese girls had low appearance competence, and 10% and 20%, respectively, had low global self-worth. Body dissatisfaction mediated most of the association between BMI and low competence in boys but not in girls. CONCLUSIONS: Obesity impacts the self-perception of children entering adolescence, especially in girls, but in selected areas of competence. Obese children are at particular risk of low perceived competence in sports, physical appearance, and peer engagement. Not all obese children are affected, although the reasons for their resilience are unclear. Quantifying risk of psychological distress alongside biomedical risk should help in arguing for more resources in child obesity treatment.

Adolescent↗

PubMed2005

Children's residential weight-loss programs can work: a prospective cohort study of short-term outcomes for overweight and obese children.

OBJECTIVE: The evidence base for child obesity treatment is weak. Children's weight-loss camps, despite their popularity, have not been properly evaluated. This study evaluated the effectiveness of a residential weight-loss camp program for overweight and obese children. METHODS: A total of 185 overweight children (mean age: 13.9 years) enrolled in 1 of 4 consecutive programs between 1999 and 2002 (intervention group) were compared with 94 children of similar ages who were not camp attendees, ie, 38 overweight children and 56 normal-weight children. The intervention group attended a 6-week (maximum) summer residential weight-loss camp. The program included a daily schedule of six 1-hour, skill-based, fun, physical activity sessions, moderate dietary restriction, and group-based educational sessions. All children were assessed for body weight, height, and other anthropometric measures, blood pressure, aerobic fitness, self-esteem, and selected sports skills. RESULTS: Campers, who stayed for a mean of 29 days, lost 6.0 kg, reduced their BMI by 2.4 units, and reduced their BMI SD scores by 0.28. Fat mass decreased significantly (from 42.7 to 37.1 kg), whereas fat-free mass did not change. In contrast, both comparison groups gained weight during this period. Camp attendees also showed significant improvements in blood pressure, aerobic fitness, and self-esteem. Longer durations of stay were associated with greater improvements in outcomes. CONCLUSIONS: In the short term at least, this weight-loss program was effective across a range of health outcomes. Ongoing research is examining the maintenance of these improvements. Future research should investigate whether benefits can be generalized across weight-loss camps and how the intervention can be adapted to nonresidential, term-time settings.

Adolescent↗

PubMed2004

Cognitive change in obese adolescents losing weight.

OBJECTIVES: To investigate how obese adolescents think about themselves in terms of exercise, eating, and appearance and whether these cognitions change over the course of a residential weight loss camp. RESEARCH METHODS AND PROCEDURES: Obese adolescents [N = 61; age, 14.1 (+/-0.2) years; BMI, 33.9 (+/-0.7) kg/m(2)] completed assessments of body weight and height and self-esteem and a sentence-completion test eliciting thoughts and beliefs about exercise, eating, and appearance at the start and end of the camp (mean stay, 26 days). They were compared with a single assessment of 20 normal-weight adolescents [age, 15.4 (+/-0.2) years; BMI, 21.8 (+/-0.5) kg/m(2)]. RESULTS: The obese adolescents lost 5.7 kg and reduced their BMI SD score by 0.25. Camp residence was associated with a significant reduction in the number of negative automatic thoughts and an increase in positive thoughts, especially related to exercise and appearance. There was no change in conditional beliefs, either functional or dysfunctional. Including BMI SD score change as a covariate took away all the main and interaction effects of time, showing that cognitive change was largely accounted for by the reduction in weight. Despite this improvement, campers remained cognitively more negative and dysfunctional than the normal-weight comparison adolescents. DISCUSSION: Obese adolescents not only lost weight, but they improved their self-representation, specifically in terms of automatic thoughts about exercise and appearance. Although these are short-term cognitive changes, they reflect positively on the camp experience and show the value of psychological improvement in assessing obesity-treatment outcomes.

Adolescent↗

PubMed2004

Does dieting make you fat?

Dieting Makes You Fat, the title of a 1980s book on weight control, is a popularised paradox, conveying a conclusion that is consistent with personal experience and the reported failure of most dietary approaches in the treatment of obesity. Few studies have been designed specifically to test this association. Yet there are prospective data showing that baseline dieting or dietary restraint increases the risk of weight gain, especially in women. Metabolic adaptations and the disinhibited eating of restrained eaters have been the most commonly cited explanations for such weight gain. Dietary restraint has also been implicated in the development and persistence of binge eating. The present paper critically evaluates the evidence supporting this paradox and reaches a rather different conclusion.

Diet↗

PubMed2002

Food cravings and aversions during pregnancy: relationships with nausea and vomiting.

Food cravings and food aversions are common during pregnancy. A mechanism that may explain these changes in food preference is taste aversion learning. Accordingly, this study examined the temporal association between the first occurrences of nausea, vomiting, food cravings and food aversions during pregnancy. Ninety-nine women completed a questionnaire that asked about the occurrence, timing of first onset, duration, strength and targets of these symptoms. Nausea and vomiting were reported by 80% and 56% of the women, food cravings and aversions by 61% and 54% respectively. Although more women experienced both food cravings and aversions than either symptom alone, cravings and aversions were statistically unrelated. There was a significant positive correlation between week of onset of nausea and of aversions. In 60% of women reporting both nausea and food aversions, the first occurrence of each happened in the same week of pregnancy. No such association was found for cravings. These retrospective accounts provide good support for taste aversion learning as a mechanism for the development of some but not all food aversions during pregnancy. Prospective data are needed to confirm these temporal relationships and to assist understanding of the emergence of food cravings.

Adult↗

PubMed2002

Developmental issues in attitudes to food and diet.

As a rule, children and most adults eat what they like and leave the rest. They like and consume foods high in fat and sugar. Parental behaviour shapes food acceptance, and early exposure to fruit and vegetables or to foods high in energy, sugar and fat is related to children's liking for, and consumption of, these foods. Some parents are imposing child-feeding practices that control what and how much children eat. However, over-control can be counter-productive, teaching children to dislike the very foods we want them to consume, and generally undermining self-regulation abilities. The external environment is also important, with concerns expressed about food advertising to children and girls dieting for an ideal thin body shape. Up to one-quarter of young adolescent girls report dieting to lose weight, their motivation driven by weight and shape dissatisfaction. For some, dieting and vegetarianism are intertwined and both legitimised as healthy eating. For others, striving for nutritional autonomy, the choice of less-healthy foods is not just because of their taste, but an act of parental defiance and peer solidarity. The determinants of what children choose to eat are complex, and the balance changes as children get older. A better understanding is crucial to informing how we might modify nutritional behaviour. Adults occupy a central position in this process, suggesting that children should be neither the only focus of nutritional interventions nor expected to solve the nutritional problems with which adults around them are continuing to fail.

Adolescent↗