• E-mail
• Print
• Comment
• Font Size
• Digg
• del.icio.us
• Discuss article

Childhood Obesity: Diagnosis, Prevalence and Implications for Health

Posted on: Thursday, 17 February 2005, 03:00 CST

TACKLING CHILDHOOD OBESITY

In this update JOSEFINE MAGNUSSON outlines the current policy context relating to childhood obesity, up-to-date recommendations for identifying and diagnosing obesity in this age group, estimated prevalence based on standardised measurements, and what the health implications for obese children and adolescents are. Although the focus is on obesity, overweight is also discussed, as a risk factor for becoming obese and has negative implications for health and well- being

Community practitioner 2005; 78, 2: 66-68

Over the last year or so, the interest in overweight and obesity in Britain has increased dramatically. Government reports and media headlines have reinforced the message that obesity is becoming a huge problem, and the rapid increase in obesity in England has even been described as 'epidemic'.'

The economic cost of obesity plus overweight has been conservatively estimated at 6.6 to 7.4 billion per year.' The rising prevalence of both overweight and obesity in children has been of particular focus.

Childhood obesity In Britain

In 2002, using the International classification of obesity (see later), the Health Survey for England reported that for two to 15- year-olds, 21.8 per cent of boys and 27.5 per cent of girls were either overweight or obese.^ Data showed that prevalence had increased from 1995-2002 for both girls and boys.

Overweight and obesity is virtually always a result of a negative energy balance, ie greater number of calories consumed than expended.

Surveys show that young people in this country are becoming increasingly inactive,^ and that they cat less than half the recommended levels of fruit and vegetables while exceeding recommendations for fat, sugar and salt/

In spring 2004, the House of Commons Select Health Committee published their report into obesity.'

It criticised the government for failing to recognise the complexity of addressing obesity in the population and suggested that obesity prevention and treatment has not been of high priority to PC]Ts. It recommended establishment of a strategic framework specifically for prevention and treatment of obesity in the NHS, and in particular recommended screening and increased access to services for children.

It was recommended that all children should be screened for overweight and obesity annually in the school setting, with results kept confidential to avoid stigmatisation and sent to parents together with advice on action, if appropriate.

Since May, policy documents addressing childhood obesity have been published, most notably the National Service framework (NSF) / or Children, Young People and Maternity Services, and the White Paper on health, Choosing health.

NSF for children and young people

The growing problem of obesity is recognised within the recent National Service Framework (NSF) for Children, Young People and Maternity Services, and strategies relating to diet and activity are proposed.'1

Health promotion is one of the core standards of the NSF. The importance of prevention and early intervention is recognised, and the aim is to enable children and young people to make informed choices about healthy life styles, thus empowering them to improve their own health.

The responsibility of the health sector, schools and other agencies dealing with children's health in helping them achieve this is recognised.

Choosing health White Paper

The recent White Paper states halting the growth in childhood obesity as a prime objective, and sets a national target to halt the year on year increase in obesity in children aged under 11 by 2010.'

Better education about food was recommended by the House of Commons,' and a role for health visitors in helping parents promote their children's health through, for example, advice on healthy eating, is reiterated in the White Paper.3

Diagnosis

There are several recognised methods for determining obesity and overweight, however not all are practical in a clinical setting, and their suitability for use with children vary.

Any measure of obesity is an attempt to calculate the proportion of body fat, as it is not the weight in itself that is important from a health perspective, but rather the relative contribution of fat to overall weight.

BMI

The most appropriate measurement for identifying overweight and obesity in children has been much debated, but the most commonly used (as with adults) is the Body Mass Index (BMI; weight (kg)/ height2(m2)).

It is a relatively straightforward measure and has been recommended as the preferred method for screening for obesity in clinical settings. In adults, a BMI of >25 is considered overweight, and >30 as obese. However, adults and children vary significantly with regards to body composition, and the adult cut-off points should not be used with children.

An international standard definition for children, linked to the adult cut-off points, has been established.6 Although it has been associated with low sensitivity, ie a failure to identify some obese children as obese, it has high specificity which minimises the risk that non-obese children will wrongly be diagnosed, thus avoiding stigma and unnecessary treatment.7

It has been suggested that using charts based on international reference data may be inappropriate for use within the UK, and validated centile charts, based on UK reference data, are also available.8"9

Generally, a score above the 85th centile is considered overweight and above the 95th, obese.

Skinfolds measure

BMI has been criticised for not being able to differentiate between fat and lean mass, meaning that a person with a proportionally large amount of muscle may be incorrectly identified as obese.

Skinfold callipers are used to measure the breadth of a fold of skin (usually on the upper arm, thigh, or abdomen) to obtain a measure of subcutaneous fat levels. Measurements are compared with pre-calibrated standard tables to assess an individual's body fat content.

Although recognised as a valid measure of relative body fat when carried out correctly, it is not generally used with children as it can be difficult to do, and can be intimidating for the child.

Waist circumference

Even when used as an accurate estimate of fat mass, BMl does not say anything about the distribution of fat. This is important, as fat accumulated around the waist (and visceral fat in particular) is known to have greater implications for health than fat posited in other areas.

In children, abdominal obesity has been associated wilh cardiovascular risk factors; adverse lipicls and lipoprotcins, and blood pressure." Waist circumference has also been found to have increased more steeply than BMI, indicating increased abdominal, relative to whole body, obesity."

Centiles for waist circumference in children have been developed,12 and may be useful in addition to BMI to establish increased risk.

Other ways of accurately determining body fat percentage include underwater weighing and dual-energy X-ray absorptiomctry (DEXA); however as they are impractical and rarely (if ever) used for screening for obesity in clinical settings they will not be discussed here.

The health imputations of childhood obesity

Some predict that today's generation of children will be the first for over a century with a life expectancy shorter than that of their parents.

In adults, obesity has long been known to be associated with a range of health problems such as coronary heart disease, diabetes and cancer.' In contrast, overweight and fatness in children was long considered to be less problematic. Indeed, there has in the past been a perception that young children and inrants in particular 'should' be fat, and that this would be a sign of good health.

However, obesity during childhood, and adolescence in particular, tend to predict continued overweight and obesity through adulthood, making it an indirect cause of such disease. I'urther, the evidence is now mounting that overweight in childhood can have serious implications for health even at a young age.

High BMI has been associated with morbidity in childhood, tracking of obesity into adulthood, and with cardiovascular risk factors.

Obesity during adolescence has been found to increase likelihood of middle-age mortality even after adult BMI has been controlled for." Further, there is now evidence that the insulin resistance syndrome (clustering of obesity, hyperglycacmia, hyperinsulinemia, dyslipidemia, and hypertension), previously associated with obesity in adults, is occurring in children.10

Cordiovoscular health

Overweight and obesity in young people have been linked to early development of atherosclerotic lesions, a risk factor for increased incidence of coronary heart disease.10

Normal weight children who become overweight show significant adverse changes in both serum high-density cholesterol and apolipoprotcin B cholesterol levels.14

In one large study of children aged five to 17 years, it was found that by using overweight as a screening tool, 50 per cent of children with two or more risk factors for cardiovascular disease could be identified."

Although disease may not present until adulthood, it is important to note that risk factors build up over time and treating obesity in childhood may significantly decrease individual risk of developing heart disease in the future, and so greatly increase prospective health and even life expectancy.

Diabetes

The type of diabetes associated withobesity is type 2 diabetes mellitus, also known as noninsulin-dependent, or adult-onset, diabetes. The latter term is telling, as until relatively recently this type of diabetes was rarely diagnosed in children and young people but was described as having a typical onset after 40 years of age.

The diagnosis of type 2 diabetes in young people has increased dramatically over the last few years, and although it may partly be explained by improved screening, it has been linked to the rising prevalence of childhood obesity.10

The glucose tolerance test is a test of the body's ability to metabolise carbohydrates, and is often used to assist diagnosis of diabetes. Used in young people, a fifth to a quarter of obese children and adolescents have been found to have impaired glucose tolerance.1" Although not all of them will be diagnosed as diabetic, it gives an indication of the implications of obesity on type 2 diabetes mellitus for young people.

Iron deficiency

Recent study has also found an increased risk of iron deficiency among overweight and obese young people, with increased risk correlating with increased BMI. The risk appears particularly marked for adolescents.16

Emotional well-being

Although the risk to physical health is the issue that appears to have received most attention, the first negative health outcomes of obesity in children are often psychological.

Evidence shows that overweight children are more likely to be victims of bullying than their normal weight peers17 and are even perceived as less intelligent by their teachers.1

Very young obese and non-obese children do not tend to differ markedly in self-esteem, but by age five a difference has already been noted whereby obese children show lower self-esteem.18

By late childhood/early adolescence, obese young people have significantly lower self-esteem, and this is particularly true for girls.19

Low self-esteem is further associated with feelings of sadness, loneliness and nervousness/' suggesting a detrimental effect of obesity on emotional well-being for older children and adolescents.

Overweight children have also been found to score lower on measures of health-related quality of life, compared to normal weight children.20

Conclusions

Childhood overweight and obesity is rapidly increasing in Britain, and although the government has been accused of failing to realise the significance of the problem in the past, a number of policy documents have been published over the last year that outline strategies developed to help deal with the problem.

Although not without flaws, BMI is considered the preferred method for diagnosing obesity in children as long as the established reference charts for children are used.

Childhood obesity has many negative implications for both physical and emotional health, and it is therefore imperative that effective screening and identification of the problem is implemented, so that prevention and intervention can be put in place as early as possible.

The next part of this update will deal with the evidence of effectiveness of interventions designed to prevent and treat obesity in young people.

Childhood obesity has many negative implications for both physical and emotional health, and it is therefore imperative that effective screening and identification of the problem is implemented, so that prevention and intervention can be put in place as early as possible

References

1 House of Commons Select Health Committee. Obesity. Third report of session 2003-4. London: House of Commons, 2004.

2 Department of Health, Health Survey for England 2002: The health of children and young people. London: Department of Health, 2002.

3 The Food Standards Agency. The National Diet and Nutrition Survey of Young People aged 4 to 18 years. London: The Stationery Office, 2000.

4 Department of Health. National Service Framework for Children, Young People and Maternity Services. London: Department of Health, 2004.

5 Department of Health. Choosing health, London: Department of Health, 2004.

6 Cole TJ1 Bellizzi MC, FIegal KM1 Dieu WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. British Medical Journal2000; 320: 1-6.

7 Reilly JJ, Dorosty AR1 Emmctt PM, The ALSPAC Study Team. Identification of the obese child: adequacy of the body mass index for clinical practice and epidemiology. International Journal of Obesity 2000; 24; 1623-1627.

8 Cole TJ, Freeman JV, Preece MA. Body mass index reference curves for the UK, 1990. Archives of Disease in Childhood 1995; 73: 25-29.

9 Wright CM, Booth IW, Buckler J MH et al. Growth reference charts for use in the UK. Archives of Disease in Childhood 2QQ2; 86: 11-14.

10 Goran MI, Ball GDC, Cruz ML. Obesity and risk of type 2 diabetes and cardiovascular disease in children and adolescents. Journal of Clinical Endocrinology & Metabolism 2003; 88, 4: 1417- 1427.

11 McCarthy HD, Ellis SM1 Cole TJ. Central overweight and obesity in British youth aged 11-16 years: cross sectional surveys of waist circumference. British Medical journal 2003; 326: 624-627.

12 McCarthy HD, Jarrett KV, Crawley HF. The development of waist circumference percentiles in British children aged 5.0-16.9 y, European journal of Clinical Nutrition 2001; 55: 902-907.

13 Must A, Jacques PT7, Dallai GE et al, Long-term morbidity and mortality of overweight adolescents. New England Journal of Median c 1992; 327: 13501355.

14 Dwyer JT, Feldman HA, Yang M, Webber LS1 Must A, Perry CL ct al. Maintenance of lightweight correlates with decreased cardiovascular risk factors in early adolescence. Journal of Adolescent Health 2002; 31; 117-124.

15 Freedman DS, Dietz WH, Srinivasan SR, Berenson GS. The relation of overweight to cardiovascular risk factors among children and adolescents: The Bogalusa heart study. Pediatrics 1999; 103, 6: 1175-1182.

16 Nead KG, Halterman JS, Kaczorowslti JM, Auinger P, Weitzman M. Overweight children and adolescents: a risk group for iron deficiency. Pediatrics 2004; 114, 1: 104-108.

17 Janssen I1 Craig WM, Boyce WF, Picket! W. Associations between overweight and obesity with bullying behaviours in school-aged children, Pediatrics 2004; 113,5: 1187-1194.

18 Hesketh K, Wake M, Waters E. Body mass index and parent- reported selfesteem in elementary school children: evidence for a causal relationship. International Journal of Obesity 2004; 28, 10:1233-1237.

19 Strauss RS. Childhood obesity and self-esteem. Pediatrics 2000; 105, 1: e!5.

20 Friedlander SL, Larkin EK, Rosen CL, Palermo TM, Redline S. Decreased quality of life associated with obesity in school-aged children. Archives of Pediatrics and Adolescent Medicine 2003, 157, 12: 1206-1211.

Josefine Magnusson

Research Fellow

Centre for Research in Primary and Community Care

University of Hertfordshire

Copyright TG Scott & Son Ltd. Feb 2005

Source: Community Practitioner

More News in this Category