10.1 Introduction

Childhood obesity has been gaining increasing media and political attention over the last few years. The Faculty of Public Health describe the United Kingdom as being in the, “Throes of an obesity epidemic,” (FPH 2004). This chapter explores the extent of the problem both nationally and locally, highlights the current policy and describes what data is going to be recorded at a local level to monitor progress of childhood obesity in the future. It also presents a limited amount of childhood obesity data that has all ready been collected within some areas of the West Midlands.

Obesity is a condition where an individual’s body fat stores are enlarged to an extent that impairs health (Garrow and Summerbell 2000). Obesity levels are rising in the United Kingdom. The prevalence of obesity among adults in England has increased from 6% in males and 8% in females in 1980 (POST 2003) to 23.6% and 23.8%, respectively in 2004 (Health Survey for England [HSE] 2004).

Figure 10.01. Age standardised proportion of adults who are obese (BMI over 30), by year (3-year moving average) and sex for England and West Midlands].

Figure 10.01: Age standardised proportion of adults who are obese

This increasing trend for adults is reflected for childhood obesity. Between 1995 and 2003 the prevalence of obesity among children aged 2 to 10 years old increased from 9.9% to 13.7% (HSE 2005).

Figure 10.02 Trends in overweight and obesity prevalence among children (aged 2-10 with valid BMI), by survey year (1995-2003)

Figure 10.02 Trends in overweight and obesity prevalence among children

Figure 10.03 shows the obesity prevalence levels by Government Office regions for England from 2001-02. Yorkshire and Humber have the lowest (11.4%) and London has the highest (18.2%). The West Midlands has an obesity prevalence of 15.8%.

Figure 10.03: Graph to show obesity prevalence among children (aged 2-10 with valid BMI), by Government Office Region. (2001-2002)

Figure 10.03: Graph to show obesity prevalence mong children

Obesity occurring in children is important because it affects physical and mental health both in terms of the present and for the child’s future. Childhood obesity can cause considerable morbidity in terms of; hypertension, high cholesterol and exacerbations of asthma. Type II diabetes has started to be diagnosed in children in the UK. There are also psychological consequences, especially in girls. Social attitudes to obese children have worsened over the years and result in negative discrimination in later selection for university and long-term relationships. Half of obese children become obese adults (Wright 2001). Adult obesity causes a reduced life expectancy of 8-10 years mainly through premature death as a result of cardiovascular disease or complications of diabetes (Storing up problems 2004). Obesity currently costs the NHS an estimated £ 1 billion per year (Healthcare Commission 2006).

The problem of obesity has been highlighted in a wide range of government papers, for example; The Chief Medical Officer’s 2002 Annual report (DH 2002), The Wanless Report Securing Good Health for the Whole Population (Wanless 2004) and Choosing Health; making healthy choices easier (DH 2004). The key Public Sector Agreement (PSA) target for addressing childhood obesity is shared between the Department for Education and Skills (DfES), Department of Health (DH) and Department for Culture, Media and Sport (DCMS) from July 2004. This aims to:

‘Halt the year-on-year rise in obesity among children under 11 by 2010 in the context of a broader strategy to tackle obesity in the population as a whole.’

10.2 Causes of obesity

The causes of childhood obesity are complex. In general terms obesity arises from an imbalance between energy intake and energy expenditure. Genetic influences are thought to only play a minor part in the development of obesity. The World Health Organisation expert group concluded that there was ‘convincing’ evidence that sedentary lifestyles and high intake of energy dense foods led to an increased risk of obesity (WHO/FAO 2002).

In England adults’ consumption of fruit has remained fairly constant between 1975-2000 whilst vegetable consumption has declined, Figure 10.04.

Figure 10.04: Graph to show consumption of fresh fruit and vegetables by income group by head of household

Figure 10.04: Graph to show consumption of fresh fruit and vegetables by income group

There is a clear social class gradient in adults with respect to consumption of five or more portions of fruit and vegetables per day, see figure 10.05.

Figure 10.05: Graph to show consumption of five or more portions of fruit and vegetables a day: by sex and income group, 2003.

Figure 10.5: Graph to show consumption of five or more portions of fruit and vegetables a day

Information was obtained regarding the number of portions of fruit and vegetables consumed by children in the previous 24 hours through their parents or legal guardians in 2001-02 by HSE. The differences in portion consumption are not statistically significant and should be interpreted with caution due to limitations of survey design.

Figure 10.06: Graph to show the obesity prevalence among children aged 5-10, by daily fruit and vegetable consumption.

Table 10.06: Graph to show the obesity prevalence among children aged 5-10

The number of adults participating in the recommended levels of physical activity declines with age with males exceeding females across all ages.

Figure 10.07: Graph to show the proportions of adults achieving recommended levels of physical activity: by sex and age, 2003

Figure 10.07: Graph to show the proportions of adults achieving recommended levels of physical activity

The HSE 2002 questioned parents and legal guardians about their child’s levels of physical activity. This was classified into three categories:

• Active=active for 60 minutes per day for 7 days in the last week i.e. the recommended level of physical activity
• Insufficient active-active for 30-59 minutes per day for 7 days in the last week
• Sedentary- active at a lower level or not active at all.

There was no statistically significant differences observed when comparing percentage of obese children to levels of physical activity, see Figure 10.08. This reflects the complexity of the causes of childhood obesity.

Figure 10.08: Graph to show obesity prevalence among children, by physical activity status.

Figure 10.08: Graph to show obesity prevalence among children

10.3 Measurement of obesity

The introductory section gives a definition of obesity and an exploration of the causes but what actually is obesity and how will it be measured for children to ascertain if progress has been made to achieve the 2010 PSA target? In adults the matter is relatively straightforward. Obesity is measured using the Body Mass Index (BMI). This is calculated by weight (kilograms) divided by height (metres) squared (kg/m²).

Table 10.01: Table to show classification of BMI for Adults

There is debate surrounding whether BMI is the most reliable measure of obesity because it does not take into account the difference in weight as a result of muscular physique as opposed to body fat i.e. fat free mass (FFM) compared to fat mass (FM). Weight, and therefore BMI, can remain constant whilst body composition can alter, for example, fitness training can increase muscle mass and reduce FM. Health risks and outcomes appear to be more related to fat within the abdominal cavity or visceral fat mass (VFM) rather than non-visceral fat. Neither BMI nor FM correlate well with VFM or with cardiovascular risk factors so health outcomes as a result of a high BMI are difficult to predict with certainty (Owens et al 1998).

Alternative measures have been proposed, for example, waist to hip ratios and skin fold thickness. Unlike the BMI there is no consensus as to what cut off point is required for a person to be classified as overweight or obese. Currently, BMI is still the preferred option (Hall and Cole 2006).

The classification of obesity in children is more complicated because they are growing and developing all of the time. A normal BMI for children varies by gender, age and ethnicity (Hall and Cole 2006).  Growth charts that are gender and age specific need to be used to ascertain whether a child is overweight or obese.  An individual child’s weight is plotted onto the gender specific growth chart according to their age and this will then correspond to a centile.

The matter is further complicated because there are two main ways of defining childhood obesity in the UK. Different overweight and obesity prevalence estimates will be calculated depending upon which reference standard is used. The two reference standards are;

1. The 1990 UK growth charts arbitrarily set the 85th centile as overweight and the 95th centile as obese. Selecting a BMI reference point from the past and comparing the proportion of the population exceeding the threshold determines the current levels of obesity. This means that in 1990, 15% of children were defined as overweight and 5% obese.
2. The International Obesity Task Force (IOTF) International Standard curves have been developed using data from six countries (UK, Brazil, Hong Kong, The Netherlands, Singapore and United States). The cut-off centiles for overweight and obesity lead to the adult cut-off values for obesity at 18 years old i.e. 25kg/m² for overweight and 30 kg/m² for obesity which roughly correspond to the 90th and 99th centiles on the growth charts. These were based on surveys of variations in BMI with age and the clinical consequences. The advantage of this classification is that it allows international comparisons to be undertaken.

A consistent approach must be used for defining the levels of overweight and obese children for accurate population monitoring to occur. The HSE report uses the UK 1990 data classification.

10.4 Childhood Obesity Data

The current data that is available to estimate levels of childhood obesity are derived from the Health Survey for England. This is an annual national survey of approximately 16,000 adults and 4,000 children living in private households. The sampling methodology aims to make the survey representative of the whole population. The survey combines a questionnaire based interview and physical measurements including height and weight. In 2002 the focus of the survey was on the health and life style of children and young adults and over twice the number of children aged 2-10 years were interviewed during this year to give a larger sample size (8,067 children and 3,625 young people).

Historically in England, school nurses used to weigh and measure school children and this practice has continued in some areas. The data was often paper based, not recorded in a consistent manner, not collated, analysed or disseminated. Following the fourth edition of Health for all Children Report (Hall 2003) this data collection function of school nurses was discouraged and their role was developed into more of a Health Promotion function. There is a huge variation across the country as to what data is collected, if at all, at a local level.

The HSE data was going to be used to inform progress on the PSA target.  The Government acknowledged the lack of data collected at a local level and in spring 2006 guidance to Primary Care Trusts (PCTs) was issued for measuring childhood obesity levels. PCTs will be required to measure the height and weight for children attending state maintained Primary Schools in the following year groups;

• All Primary School children in the Reception year (ages 4-5 years)
• All Primary School children in Year 6 (ages 10-11 years).

A sampling methodology was considered and rejected because this may have resulted in inaccurate monitoring of childhood obesity levels so all children in the above categories are to be measured. PCTs may approach independent and schools for children with special needs, depending upon the local circumstances.

The following information will be collected on each child;

• Full Name
• Date of birth
• Gender
• School name, address and year
• Date of measurement
• Height (in centimetres)
• Weight (in kilograms)

The practicalities of how PCTs collect this data or how this data will be stored will be locally determined. In some areas the Child Health Surveillance system will be modified for this use and in others specially designed databases will be developed.

The individual child’s BMI will not be calculated at the time of measurement. The aim of this data collection is for population monitoring and not screening. Population monitoring is defined as taking measurements of the defined population and using these measurements in an anonymised fashion to describe the population as a whole. The Expert Advisory Group and the National Screening Committee have stressed that this is not a screening programme for the following reasons;

1. There is no agreed cut-off point in children that can be consistently linked to an increase in morbidity or mortality
2. There is insufficient evidence to support the effectiveness of any interventions for obesity in individuals identified through screening who are otherwise not concerned about their weight and
3. Screening for weight may cause psychological harm to the child or their family.

Parents and guardians can however subsequently contact the PCT and request the BMI for their child, providing this is given within a clinical context.

10.5 West Midlands

In some areas of the West Midlands data collection of Primary School children’s height and weight has continued to be recorded but for different year groups than detailed in the current PCT Guidance, for example Reception and Years 5 & 7.

Table 10.02 summarises the prevalence of overweight and obesity for the different year groups comparing the IOTF and UK 1990 classifications. As can be seen in table 10.02 the UK 1990 classification prevalence estimates are greater than the IOTF classification. Overall prevalence estimates for overweight and obesity are 24% and 7% for the IOTF classification and 35% and 20% for the UK 1990 classification. This is above the HSE estimate for obesity of 15.8% for the West Midlands Regional Office area.

10.6 Summary

Obesity is an increasing problem in the UK for adults and children. The causes are complex and the effects are far reaching, not only for the affected individuals but also for society. The limited amount of data presented here shows that the national estimates may be underestimating the extent of the problem in the West Midlands, depending upon which classification is utilised. A consistent approach will be required for the future data collection so that meaningful trends can be explored and geographical areas identified so that evidence based interventions can be commissioned, provided and evaluated.

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