Discussion

The lack of ethnic variation in this sample reflects the ethnic composition of Wirral and Cheshire since labour force survey data indicates that these areas have among the lowest concentrations of non-white ethnic minorities in the country (Hastings 2002). The low levels of ethnic minorities meant that no analyses based on ethnicity could be carried out, and since there are well documented differences in weight, weight concerns and weight control between women and girls of different ethnic groups (Neff et al 1997; Wardle and Marsland 1990; Kumanyika 1987), the results of analyses from this study may not extrapolate to samples of different, or mixed, ethnic origin.

The broad socioeconomic mix demonstrates that the stratified sampling process was successful in involving participants from a wide range of social backgrounds. Participants were drawn from all levels of the registrar general’s occupational classification, although this measure seems to suggest a predominance of participants at the upper end of the scale. It appears likely, however, that the lower social class occupations are under-reported, as many of the unclassifiable responses gave the name of local factories or supermarkets, where the majority of employees are in low skilled employment (e.g. Cadbury's, Sainsbury's). In addition all those households in which no parent was in employment are unclassifiable. The proportion of pupils reporting that they are eligible to receive free school meals (32%) supported the proposition that there were a large number of participants at the lower end o f the socio-economic spectrum.

Over two thirds of young people in this sample are o f an appropriate weight for their age. O f some concern, however, is the fact that already around a quarter of participants are classified as overweight or obese using the Cole et al (2000) criteria. This indicates that their current weight suggests that they are likely to have a BMI exceeding 25 by the time they are 18 years old. These figures are striking given that weight usually increases throughout adult life (Erens and

Chapter 4. Baseline methodology and descriptive statistics

Primatesta 1999), meaning that this is likely to be a considerable underestimate of the number who will eventually become overweight adults. Striking evidence of the increase in the body weights of young people emerges from the underweight classification. The cut-off point for underweight used here represented the 9^^ percentile of a 1990 sample of British adolescents, whereas in the present study it identifies less than 4% of the sample. Reilly and Dorosty (1999) showed that levels of overweight and obesity in a 1996 representative sample of children significantly exceeded the numbers expected based on the 1990 figures. The findings from the present sample seem to suggest that similar weight increases are occurring at the lower end o f the weight distribution, although these figures must be interpreted with caution since the present sample is not representative of the UK population.

Just over half of the sample are satisfied with their current body size, indicating that a large minority are experiencing body dissatisfaction to some degree. Whilst other published studies suggest that weight concerns are increasing by age during early adolescence (Wardle and Marsland 1990, Davies and Fumham 1986) there is no evidence here of differences in dissatisfaction between the older and younger year groups. This may be a result of using two adjacent year groups, and by doing so minimising levels of age variation.

Despite a large number of girls expressing dissatisfaction, these data do not provide much support for the suggestion that girls have hugely distorted ideas of their own body size. Over half of girls place themselves in the ‘correct’ weight category, such that their perception of their weight corresponds to the categories produced by Cole et al (2000). Almost all the remaining participants place themselves in an adjacent category, and only a very small number appear to have a body image which is severely discrepant from health-related weight categories. Not all cases of inaccuracy reflect overestimates of weight status. Of those who place themselves 'wrongly', around one in three place themselves in a thinner category than might be considered appropriate, whilst the remainder perceive themselves to be fatter than they are.

Chapter 4. Baseline methodology and descriptive statistics

Just over two-thirds of participants reported having tried to control their weight in the past, whilst just under 60% said that they had been on a diet in the past year. It is interesting that more participants report weight control than report weight dissatisfaction. This suggests that some adolescent weight control behaviour may be orientated towards achieving an ideal, desired body size, rather than reflecting a desire to assuage negative feelings about current weight. It also implies than weight control in itself cannot be taken as an indicator of body weight distress. It is not clear whether those who say that they have tried to control their weight in the past but have not dieted in the past year, have abandoned weight control in the past year and are now no longer using any weight control practices, or whether they have controlled their weight in the past year in ways that they would not refer to as dieting.

These descriptive statistics indicate that, in line with expectations, weight control and weight concern have affected the majority of adolescent girls in this sample. The following chapter examines the dieting behaviour of these girls in more detail, and goes on to discuss some of the social, developmental, psychological and behavioural factors that are associated with adolescent dieting.