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The Scottish Health Survey: Volume 1: Main Report

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Chapter 7 Adult and Child Obesity

7 ADULT AND CHILD OBESITY

Linsay Gray and Alastair Leyland

SUMMARY

  • Between 1995 and 2010, the proportion of adults aged 16-64 who were overweight or obese ( BMI of 25 kg/m 2 and over) increased from 52.4% to 63.3%. The equivalent figures were 55.6% and 66.1% for men, and 47.2% and 60.3% for women.
  • There has also been a steady upward trend in the prevalence of obesity ( BMI of 30 kg/m 2 and over) in adults aged 16-64, from 17.2% in 1995 to 27.4% in 2010 (15.9% and 26.6% for men, and 17.3% and 28.1%, for women).
  • Most of these increases occurred in the 1995-2008 period, as the 2008, 2009 and 2010 figures were very similar.
  • Morbid obesity rates ( BMI 40kg/m 2 or more) in adults aged 16-64 increased from 1.2% in 1995 to 2.7% in 2003, and fluctuated between 2.2% and 2.7% between 2008 and 2010.
  • Mean BMI has also increased over time from 25.8 kg/m 2 $1in 1995 to 27.4 kg/m 2 $1in 2010 among adults aged 16-64.
  • In 2010, 65.1% of all adults aged 16 and over were overweight or obese. Men were more likely than women to be overweight or obese (67.8% versus 62.4%).
  • 28.2% of adults aged 16 and over in 2010 were obese. The figures were similar for men (27.4%) and women (28.9%).
  • Obesity increased significantly with age, from 13.3% in those aged 16-24 to a peak of 38.3% in those aged 55-64. The combined prevalence of overweight and obese was also lowest in adults aged 16-24 (33.8%) and highest (77.9%) for those aged 55-64.
  • In 2010, 29.9% of children (31.1% of boys and 28.5% of girls) were overweight or obese. 15.6% of children aged 2-15 were overweight (>=85 th percentile and <95 th percentile), 7.4% obese (>=95 th percentile and <98 th percentile), and 6.9% morbidly obese ( BMI >=98 th percentile).
  • 32.5% of children had a BMI outwith the healthy range (<=5 th percentile or >=85 th percentile). The proportions of boys (34.0%) and girls (30.9%) with a BMI outside the healthy range were not significantly different.
  • The proportion of children with a BMI outwith the healthy range increased with age, from 28.7% of children aged 2-6, to 33.4% of those aged 7-11 and 35.7% of those aged 12-15.
  • The proportion of girls with a BMI outwith the healthy range, or who were overweight/obese, did not vary significantly between 1998 and 2010. The prevalence of overweight/obesity and BMI outwith the healthy range among boys has fluctuated over the years. Prevalence peaked in 2008, followed by a decline in 2009 and a slight increase again in 2010.

7.1 INTRODUCTION

Obesity has a major impact on people's quality of life and health, increasing their risk of type 2 diabetes, hypertension, cardiovascular disease, osteoarthritis and cancer. [1] Scotland has one of the worst obesity records amongst developed countries. The estimated cost to the NHS in Scotland of obesity and related illnesses in 2007/8 was in excess of £175 million. [2] With these economic and health costs, tackling obesity is a key priority for the public health sector in Scotland.

The Scottish Government's commitment to this issue is underpinned by the National Performance Framework national indicator [3] on child healthy weight which is being monitored via the Scottish Health Survey: [4]

Reduce the rate of increase in the proportion of children with their Body Mass Index outwith a healthy weight

An NHS Scotland HEAT [5] target was established in 2008/09 to deliver 6,317 child healthy weight interventions by March 2011. This led to the setting up of a variety of prevention and/or treatment services for overweight and obese children by NHS Boards across Scotland and 8,406 interventions were delivered during the target period. [6] This target has been extended to cover the April 2011 to March 2014 period with a new requirement that at least 40% of such interventions should be delivered to children living in the two most deprived SIMD quintiles. 6

The introductions to the obesity chapters in the 2008 [7] and 2009 Reports [8], [9] provided a detailed overview of the recent policy context in Scotland. These included:

  • The Scottish Government's Healthy Eating, Active Living: An action plan to improve diet, increase physical activity and tackle obesity. [10]
  • The Keep Well initiative. [11]
  • The Scottish Government's Route Map for tackling obesity. 2
  • The Scottish Intercollegiate Guidelines Network ( SIGN) national clinical guideline on obesity management. [12]

In addition, a number of policy actions targeted specifically at improving children's diets (described in Chapter 5) and physical activity levels (described in Chapter 6) are also relevant in the context of tackling obesity.

The most important recent development is the publication of the Obesity Route Map Action Plan[13] which covers energy consumption and active living. Food product reformulation, portion sizes, stocking policies, pricing, packaging, and advertising, will each be addressed by liaising with the food and drink industry, consumer groups, schools and the public sector, and using social marketing and licensing. Opportunities around transport, provisions for open space and sporting activities will be explored, as well as a focus on early life. A set of 16 indicators and associated desired outcomes to help monitor the progress of the Obesity Route Map's actions has also been published. [14] The Scottish Health Survey is the measurement tool for seven of these indicators, including the following two long-term goals: the majority of Scotland's adult population in normal weight throughout life, and fewer children in Scotland overweight or obese. The introductions to the chapters on diet ( Chapter 5) and physical activity ( Chapter 6) describe the other outcomes being measured via the survey.

This chapter focuses on body mass index ( BMI), derived from the direct measurements of height and weight taken in the main interview. Time trends over the 1995-2010 period in adult BMI are examined by age and sex. Trends in the prevalence of overweight and obesity in children from 1998-2010 by age and sex are also presented.

7.2 METHODS AND DEFINITIONS OF MEASUREMENT

Full details of the protocols for carrying out the measurements are contained in Volume 2 of this report and are briefly summarised here.

7.2.1 Height

Height was measured using a portable stadiometer with a sliding head plate, a base plate and three connecting rods marked with a metric measuring scale. Participants were asked to remove shoes. One measurement was taken, with the participant stretching to the maximum height and the head positioned in the Frankfort plane. [15] The reading was recorded to the nearest millimetre.

7.2.2 Weight

Weight was measured using Soehnle and Tanita electronic scales with a digital display. Participants were asked to remove shoes and any bulky clothing. A single measurement was recorded to the nearest 100g. Participants aged under 2 years, or who were pregnant, or chairbound, or unsteady on their feet were not weighed. Participants who weighed more than 130 kg were asked for their estimated weights because the scales are inaccurate above this level. These estimated weights were included in the analysis.

In the analysis of height and weight, data from those who were considered by the interviewer to have unreliable measurements, for example those who had excessive clothing on, were excluded from the analysis.

7.2.3 Body Mass Index ( BMI)

The Body Mass Index ( BMI), defined as weight (kg)/height (m 2), is a widely accepted measure that allows for differences in weight due to height. It has been used in each Scottish Health Survey report to date. However, BMI has some limitations. [16], [17] It does not distinguish between mass due to body fat and mass due to muscular physique. It also does not take account of the distribution of fat.

BMI was calculated for all those participants for whom a valid height and weight measurement was recorded.

Adult BMI classification

Adult participants were classified into the following BMI groups: [18]

BMI (kg/m 2)

Description

Less than 18.5

Underweight

18.5 to less than 25

Normal

25 to less than 30

Overweight

30 to less than 40

Obese, excluding morbidly obese

40+
Morbidly obese

Other cut off points are also used in analyses of obesity, for example the World Health Organisation ( WHO) cites evidence that chronic disease is an increasing risk in populations when BMI exceeds 21, [19] while mortality rates do not necessarily correlate neatly with the categories presented here. [20] However, meaningful comparisons of prevalence estimates between countries require agreed thresholds and these categories correspond with the WHO's recommended definitions for underweight, normal, overweight and obese (though they use three sub-classifications of obesity rather than the two presented here). [21] The tables of age and sex report mean BMI and prevalence of the five categories outlined above. Although obesity has the greatest ill-health and mortality consequences, overweight is also a major public health concern, not least because overweight people are at high risk of becoming obese, while underweight also has negative health consequences. The trend tables present three measures: the proportion who are either overweight or obese ( BMI of 25 kg/m 2 or more), the proportion who are obese ( BMI of 30 kg/m 2 or more), and the proportion morbidly obese ( BMI of 40 kg/m 2 or more). The latter group $1are at particularly high risk of morbidity and mortality. [22]

Children's BMI classification

Body Mass Index ( BMI) in children is defined in the same way as it is for adults: weight (kg)/height (m 2). However, despite the relatively wide acceptance of the use of BMI as an adiposity indicator, the establishment of a specific obesity and overweight classification system for children and young people has proved to be difficult. Constant changes in body composition during growth mean that the relationship between weight-for-height and adiposity during childhood and adolescence is age-dependent, and this relationship is further complicated by ethnicity and gender. [23] Several methods have been employed to define early life overweight and obesity, including body fatness as measured by skinfold thickness, [24], [25] national BMI percentile charts, [26], [27], [28] weight-for-height indices, [29]BMI percentile cut-off points, [30] and international [31] and national [32]BMI cut-off points.

Percentile charts can be used to compare an individual child's BMI with the distribution of BMI in a reference population to see whether it corresponds with the average or whether it is unusually high or low. Since children's BMI changes as they age, the comparison needs to be age specific. For example the BMI for a child of 5 needs to be compared with a reference population with a large sample of 5 year olds rather than data for children with a wide age range.

The classifications of children's BMI used in this chapter, set out below, have been derived from BMI percentiles of the UK 1990 reference curves 27,28 (referred to as the National BMI percentiles classification); these have been used in all the Scottish Health Surveys to date. SIGN recommends that these reference curves and thresholds should be used for population surveillance in Scotland. 12

Percentile cut-off

Description

At or below 5 th percentile

Underweight

Above 5 th percentile and below 85 th percentile

Healthy weight

At or above 85 th percentile and below 95 th percentile

Overweight

At or above 95 th percentile and below 98 th percentile

Obese

At or above 98 th percentile

Morbidly obese

The 85th / 95th cut-off points are commonly accepted thresholds used to analyse overweight and obesity in children. These thresholds have previously been used to describe childhood overweight and obesity prevalence trends in the UK. [33],[34], [35], [36] The National BMI percentiles classification has been shown to be reasonably sensitive ( i.e. not classifying obese children as non-obese) and specific ( i.e. not classifying non-obese children as obese). [37], [38] As noted in the introduction, one of the Scottish Government's National Indicators relates to healthy weight in children, defined as neither underweight nor overweight / obese. For this reason the data have been categorised to show the total proportions that are overweight, obese or morbidly obese, as well as the proportion underweight.

The use of reference curves require children's ages to be exactly matched to those in the reference population charts. This is a fairly straightforward process in clinical settings where an individual child's exact age can be compared with the look-up chart for their age. Matching exact ages to population charts in a survey dataset containing many children is somewhat less straightforward. The Scottish Health Survey uses a method developed by ISD Scotland that plots the exact ages of the children in the sample against the reference population data. [39]

Although children's exact age was used to calculate the BMI grouping prevalence rates (based on the interview date and the date of birth), the results are presented using grouped ages based on age at last birthday.

7.3 RESPONSE TO ANTHROPOMETRIC MEASUREMENTS, BY AGE AND SEX

Response among adults to the height and weight measurements is shown in Table 7.1, and among children in Table 7.2. Similar proportions of men (87%) and women (85%) had their height measured, though more men than women had their weight measured (86% versus 83%). Proportions with known values for both height and weight, and thus derived BMI, were similar to those for weight alone (85% of men and 82% of women). Response to height generally declined with age and was lowest among men and women aged 75 and over (72% and 66%, respectively) compared with 84%-91% of men, and 84%-92% of women, aged under 75. The patterns by age for weight and BMI were broadly similar to this. The proportion of those aged 75 and over who refused to have these measurements taken was not much higher than the average for all adults, however people aged 75 and over were the most likely to have not been measured due to physical difficulties with standing, which explains the lower response for this age group (data not shown). Table 7.1

Children's response to measurements was a little lower than adults'. 83% of boys aged 2-15 had their height and weight measured while 81% of girls had their height measured, and 82% had their weight measured. Children aged 2-6 were less likely to have been measured than those aged 7-15. For example, 73% of boys aged 2-6 had a valid BMI measurement compared with 88% of those aged 7-11, and 85% of those aged 12-15. The equivalent figures for girls were 76% at age 2-6 and 83% for those aged 7-15. Younger children were more likely than their older counterparts to have refused the measurements and to have not been available at the time the interview was conducted (data not shown). Table 7.2

7.4 TRENDS IN THE PREVALENCE OF ADULT OVERWEIGHT AND OBESITY

This section presents figures for the prevalence of obesity ( BMI 30 kg/m 2 or more), morbid obesity ( BMI of 40 kg/m 2 or more), and overweight, including obese ( BMI 25 kg/m 2 or more) in each survey year to date - 1995, 1998, 2003, 2008, 2009 and 2010. Figures are presented for all adults, and for men and women separately. Adults' BMI in 2010 is described in more detail in Section 7.5.

Variations in the sample composition over the first three Scottish Health Surveys mean that the trend figures presented for adults between 1995 and 2010 are for those aged 16-64 only. The trend for adults of all ages (16 and over) is also shown for 2003 onwards.

7.4.1 Obesity and morbid obesity

Table 7.3 and Figure 7A shows that the prevalence of obesity ( BMI 30 kg/m 2 or more) among adults aged 16-64 has risen significantly over the last fifteen years. Between 1995 and 2010, there was just over a ten percentage point increase in the proportion of adults aged 16-64 who were obese (from 17.2% to 27.4%). Within this period, the greatest increase was between 1995 and 2003 (17.2% to 23.0%).

The pattern seen for all adults aged 16-64 was the same among both men and women. The greatest increases occurred between 1995 and 2003 (from 15.9% to 22.0% for men, and from 17.3% to 23.8% for women). The 2010 figures (26.6% for men and 28.1% for women), were significantly higher than the 1995-2003 survey years, but were not significantly different from those in 2009 (26.7% and 26.4%, respectively) or 2008 (24.9% and 26.5%, respectively). While this could be indicative of a plateau in the trend it may not necessarily be the case. Intervals between all the previous surveys (1995, 2003 and 2008) were much larger, and it is possible that the results for any three sequential years during that period might also have been very similar. Further prevalence data on 2011 will help establish whether the increase over time has begun to plateau.

Trends in obesity for all adults aged 16 and over since 2003 have followed the same long-term pattern for those aged 16-64 detailed above, with a significant increase in the prevalence of obesity from 24.2% in 2003 to 28.2% in 2010. Although the 2003 and 2008 figures were not significantly different and the equivalent figures in 2008 (26.8%) and 2009 (27.2%) were not significantly different to the 2010 figure, the steady increases over time in obesity prevalence has resulted in a significant difference opening up between 2003 and 2010.

The prevalence of obesity among men aged 16 and over increased significantly from 22.4% in 2003 to 27.4% in 2010, and among women the equivalent figures were 26.0% and 28.9%, respectively.

Although relatively low in absolute terms, the prevalence of morbid obesity ( BMI of 40 kg/m 2 or more) in adults aged 16-64 has increased over time. The levels were lower in 1995 (1.2%) and 1998 (1.4%) than the equivalent figures in the 2003-2010 period, which fluctuated between 2.2% and 2.7% with no clear pattern. The patterns for men and women aged 16-64 were somewhat different; between 0.5% and 1.8% of men were morbidly obese each year but with no pattern to the fluctuating figures, whereas women, on the other hand, have remained fairly constant since 2003 (3.6%-3.7%) compared with 1.3% in 1995.

Table 7.3, Figure 7A

7.4.2 Overweight and obesity

The prevalence of overweight including obese ( BMI 25 kg/m 2 or more) has also risen over time among adults aged 16-64, from 52.4% in 1995, to 60.6% in 2003, and to 63.3% in 2010. As with many of the figures cited above, the proportion of adults aged 16-64 who were overweight or obese between 2008 and 2010 did not change significantly. In percentage point terms, the increase in the prevalence of overweight or obese between 1995 and 2010 was larger for women (from 47.2% to 60.3%) than for men (from 55.6% to 66.1%).

Looking at all adults aged 16 and over, in 2003 62.4% were overweight or obese, compared with 65.1% in 2010 (the 2008, 2009 and 2010 figures were almost identical). This small increase in prevalence between 1995 and 2010 was seen in both men (from 65.4% to 67.8%) and women (59.7% to 62.4%), while the figures for the 2008-2010 period were largely the same. Table 7.3, Figure 7A

Figure 7A

7.4.3 Mean BMI

Mean BMI in adults aged 16-64 has also increased significantly, from 25.8 kg/m 2 in 1995 to 27.4 kg/m 2 in 2010 (the figures for 2008-2010 were very similar and ranged between 27.2 kg/m 2 and 27.4 kg/m 2). This pattern of an increase in mean BMI across this period was true for both men and women. A similar trend was evident among all adults aged 16 and over since 2003. Mean BMI increased significantly - albeit very slightly - from 27.1 kg/m 2 in 2003 to 27.5 kg/m 2 in 2010, and the 2008-2010 figures were very similar. The corresponding figures for men aged 16 and over were 27.0 kg/m 2 in 2003 and 27.5 kg/m 2 in 2010, respectively, and for women, were 27.2 kg/m 2 and 27.6 kg/m 2, respectively.

The findings of broadly similar levels of obesity, and overweight including obesity, and comparable means for BMI over 2008, 2009 and 2010 (for adults aged 16-64 and all aged 16 and over) suggest that the increase over time in all these measures has begun to plateau. However, as noted in last year's report, 8 and discussed in section 7.4.1 this is not necessarily the case. The intervals between all the previous surveys (1995, 2003 and 2008) were much larger, so it is possible that the results for any three sequential years during that period might also have been very similar, even though the overall trend was upward. The prevalence data in 2011 will help further in establishing whether obesity is still increasing, has declined or has indeed stabilised. In the meantime, it is worth noting that there are continued indications of a slowing rate of increase in overweight and obesity among adults in England since the mid-2000s, [40] further to those cited in last year's report. [41],[42]Table 7.3, Figure 7A

7.5ADULT BMI BY AGE AND SEX, 2010

This section focuses on the 2010 prevalence figures for the three summary measure BMI groups - overweight including obese ( BMI of 25 kg/m 2 and over), obese ( BMI 30 kg/m 2 and over) and morbidly obese ( BMI 40 kg/m 2 and over), and- by age and sex for all adults aged 16 and over. These figures are presented in Table 7.3 and Figures 7B and 7C.

As noted above, the overall prevalence of obesity in 2010 was 28.2% (27.4% for men and 28.9% for women). However, obesity levels differed significantly by age: prevalence increased by age until late middle-age, from 13.3% in those aged 16-24 to a peak of 38.3% in those aged 55-64, whereas levels for the two oldest age groups were sequentially lower (33.0% in those aged 65-74 and 29.9% in those aged 75 and over). This pattern was similar for both sexes, though men aged 16-24 had a lower prevalence of obesity than young women (9.2% versus 17.7%) which meant that the difference between the levels for men aged 16-24 (9.2%) and those aged 55-64 (37.3%) was particularly marked. Morbid obesity prevalence in 2010 was 2.4% for all adults, and was lower in men (1.6%) than women (3.2%). The prevalence of morbid obesity peaked in the 35-54 age group (3.5%-4.3%) and this was true for both sexes.

Prevalence of overweight, including obesity, was 65.1% among all adults in 2010, and was significantly higher in men (67.8%) than women (62.4%). Overweight levels followed similar age-related patterns to obesity alone, with the largest difference evident between men aged 16-24 (29.9%) and those aged 25-34 (60.5%), a gap of 30.6 percentage points.

Adult mean BMI in 2010 was 27.5 kg/m 2 and was very similar for men (27.5 kg/m 2) and women (27.6 kg/m 2). Mean BMI values varied significantly with age from 24.3 kg/m 2 for adults aged 16-24 to a peak of 29.0 kg/m 2 for those aged 55-64, before declining to 27.8 kg/m 2 for those aged 75 and over. The age-related mean BMI patterns for men and women followed the same trajectory as for all adults. Table 7.3, Figure 7B, Figure 7C

Figure 7B

Figure 7C

7.6 TRENDS IN THE PREVALENCE OF CHILD UNHEALTHY WEIGHT, OVERWEIGHT AND OBESITY

This section focuses on three measures of BMI for children aged 2-15: obese ( >95 th percentile); overweight or obese ( >85 th percentile); and outwith healthy weight (underweight, overweight or obese; i.e. <5th percentile or >85th percentile). Figures are presented for the 1998, 2003, 2008, 2009 and 2010 surveys in Table 7.4 and Figure 7D. The detailed 2010 figures by age group are described in more detail in Section 7.7, and shown in Table 7.5.

Obesity prevalence for all children aged 2-15 was 13.0% in 1998, 14.0% in 2003, 15.1% in 2008 and 15.0% in 2009 before falling marginally to 14.3% in 2010. The separate figures for boys and girls followed different patterns. The prevalence of obesity in boys increased from 13.0% in 1998 to 15.6% in 2010, with some fluctuations in the 2008-2010 period. For girls, the prevalence has been more stable over time. It was 13.1% in 1998 and 12.9% in 2010, with some fluctuations in the intervening years (12.3%-14.7%).

The prevalence of overweight including obesity has followed a similar pattern to that for obesity: relatively little change among all children and girls aged 2-15, and larger fluctuations in the boys' figures. The overall prevalence for children aged 2-15 was 28.0% in 1998 and 30.7% in 2003, and fluctuated between 28.9% and 31.7% from 2008 onwards with no clear trend (29.9% in 2010). In contrast, it increased steadily among boys from 27.8% in 1998, to 32.4% in 2003, and then to 36.1% by 2008. The level then declined notably between 2008 and 2009 to 30.0%; the figure for 2010 is comparable (31.1%). The similarity of the figures for 2009 and 2010 reduces the possibility that the 2009 figure represents a blip, a possibility discussed in 2009 report chapter. 9 However, although the difference between 2008 and 2010 is statistically significant, this may still reflect sample fluctuation rather than a true difference in the population. The pattern for girls was different. 28.3% of girls in 1998 were overweight or obese as were 28.5% in 2010. The rates in the intervening years were very similar (26.9%-28.9%) with no statistically significant differences.

The proportion of children with a BMI outwith the healthy range, the subject of the Government's National Performance indicator, followed similar patterns in boys and girls to those described above. 29.7% of children in 1998 had a weight outwith the healthy range, increasing to 33.6% in 2008, and then fluctuating in 2009 (30.5%) and 2010 (32.5%). Among boys there was a sharp increase in prevalence from 29.2% in 1998 to 38.2% in 2008, followed by a sharp decline to 31.7% in 2009 and a small upturn to 34.0% in 2010. As the figures for the prevalence of obesity, and overweight including obesity in boys did not change much between 2009 and 2010, this increase in the proportion of boys with a weight outwith the healthy range was caused by a slightly higher prevalence of underweight boys in 2010 (2.9%, see Table 7.5) compared with 2009 (1.7%, data not shown), though note this was not a statistically significant difference. For girls, the corresponding figures were very similar each year and ranged between 28.7% in 2008 and 30.9% in 2010.

The difference between the rates of overweight and obesity, and unhealthy weight in all children between 1998 and 2010, and between 2003 and the 2008-2010 period, were not statistically significant. However, the figures for boys have changed significantly. Once the 2008-2011 data have been collected it will be possible to carry out more sophisticated analysis of the more recent year on year trends for these measures. Table 7.4, Figure 7D

Figure 7D

7.7CHILDREN'S BMI BY AGE AND SEX, 2010

This section examines the 2010 prevalence figures for the three summary BMI groups discussed above (obese; overweight including obesity; and outwith healthy weight) as well as the proportions who were underweight, by age and sex for children aged 2-15. The sample size for children in individual survey years is not sufficiently large to detect statistically significant differences between all of the sub-groups. However, we can take advantage of the analysis conducted for the 2009 report 9 which used a combined sample from 2008 and 2009 surveys which was large enough for this purpose. We can use the significant findings identified using the larger combined sample to see whether the figures in 2010 confirm these patterns, even if they are not statistically significant. The analysis of the 2008-11 combined sample will be able to provide even more robust estimates of the figures within specific sub-groups of children.

Table 7.5 shows that one in seven (14.3%) children was obese (including morbidly obese) in 2010. The prevalence appeared to increase with age, from 10.9% at age 2-6 to 17.5% at age 7-11, and then decline to 14.1% for those aged 12-15. While the difference between the youngest and the middle group was significant, the difference between the youngest and oldest was not, and this pattern of a decline among the oldest age group has not been evident in any other survey year. It is therefore inappropriate, on the basis of a single year, to conclude that the prevalence of obesity among children aged 12-15 has declined.

Overall, 29.9% of children aged 2-15 were overweight or obese and this increased with age from 26.0% for those aged 2-6, to 30.6% for those aged 7-11, and to 33.4% for children aged 12-15. The overall figures for boys (31.1%) and girls (28.5%) were similar, as were the proportions between each age group (as found in the 2008/2009 analysis). Although the gap appeared to be greatest between boys and girls aged 7-11 (33.0% and 28.1% respectively), this was not significant and was only marginally so in 2008/2009.

The proportions of children with a BMI outwith the healthy range showed similar age-related patterns to those for overweight or obese. A third (32.5%) of children in 2010 had a BMI outwith the healthy range. This increased with age: from 28.7% for children aged 2-6, to 33.4% for those aged 7-11, and 35.7% for those in the oldest age group (12-15). Although not statistically significant, the pattern follows the direction shown in the 2008/2009 analysis of higher prevalence with increasing age. As found last year, the difference in the proportion of boys and girls with a BMI outwith the healthy range was not statistically significant (34.0% versus 30.9%).

The figure for the proportion of children outwith the healthy range comprises overweight, obese and underweight children. Table 7.5 shows that the prevalence of underweight was relatively low in 2010 at 2.6% for all children aged 2-15 (2.9% of boys and 2.3% of girls), and did not vary significantly by age group. The prevalence of morbid obesity was lower among those aged 2-6 (4.2%) than those aged 7-15 (7.2%-8.9%). Table 7.5