Professional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
In the past, obesity has been seen as a problem of adults, becoming more prevalent with advancing age. Fat children have been recognised in literature with Charles Dickens' portrayal of the fat boy in The Pickwick Papers, and Billy Bunter in the 20th century. They were notable because fat children were uncommon.
Now obesity is no longer rare in children and the prevalence is increasing at an alarming rate. Pathological processes (see 'Complications', below) start early in life and are accelerated by obesity. See also separate articles Obesity in Adults and Bariatric Surgery.
- The National Child Measurement Programme (NCMP) measures the height and weight of school children in reception and Year 6 in England every year, which helps in establishing the prevalence of child obesity. In 2013/14:
- 19.1% of children in Year 6 (age 10-11) were obese.
- A further 14.4% in Year 6 were overweight.
- 9.5% of children in Reception (aged 4-5) were obese.
- A further 13.1% in Reception were overweight.
- This means a third of those aged 10-11 and over a fifth of those aged 4-5 were overweight or obese.
- Further figures are available from the Health Survey for England (HSE), which includes a smaller sample of children than the NCMP but covers a wider age range. Results from 2012 show that around 28% of children aged 2-15 were classed as either overweight or obese.
- The Millennium Cohort Study is following 19,000 children born in the UK over the turn of the century in 2000-2001.Its latest report showed that by the age of 11, 20% of children are obese, with another 15% being overweight. At the age 7 report, 7% had been obese, showing a large rise in obesity between the ages of 7 and 11.
- Obesity prevalence between nations in the UK varies, with figures for both obesity and overweight being highest in Wales and lowest in England in 2012. The Millennium Cohort Study also found highest levels of obesity at the age of 11 in Wales, with the lowest percentage being in Scotland.
- Trends show rising obesity figures from 1995, but the rate of this has slowed since 2004, particularly in older children. There was a drop in prevalence between 2012 and 2013.
- Worldwide, there has been an escalation in obesity prevalence, with an estimated 42 million children under the age of 5 affected in 2013.Low-income and middle-income countries have been affected by the same trend as richer countries. Obesity is one of the priorities of the World Health Organisation (WHO). The UK has one of the highest prevalence rates of childhood obesity in Europe.
Obesity is basically caused by an imbalance between energy input and expenditure. There are numerous factors that are thought to contribute to this trend. A few will be considered here. It is worth noting that studies investigating the role of diet or activity are generally small and include diverse methods of risk factor measurement. It is therefore difficult to establish the relative importance of the different potential contributory factors.
There is a growing cohort of children who develop bad eating habits and a taste for junk food that is high in fat and fast carbohydrates. One study found that whilst consumption of fast food was linked to obesity in those aged 13-15, public health interventions that placed restrictions on the location of fast food outlets did not uniformly decrease consumption.
Reduction of physical exercise in the absence of dietary modification contributes to weight gain. Compulsory sport is in decline, although studies suggest that school-based activity programmes aimed to promote physical exercise actually have little impact on children's body mass indices (BMIs).[6, 7]Long periods in front of the television or playing on the games console also contribute to the increasingly sedentary lifestyle.
Sleep deprivation has been suggested as a contributory factor, although a review of the literature concerning adolescents queried the methodology of many studies.A possible trend of children going to bed later may be, in part, responsible. Lack of physical exercise may also lead to poor sleep.Two hormones, leptin and ghrelin, may be important. Leptin is released by fat cells to tell the brain that fat stores are adequate and ghrelin is released by the stomach, as a signal of hunger. In people with too little sleep, leptin levels are low and ghrelin levels high. Both these would encourage an individual to eat more.
Studies suggest that obese children are likely to have obese parents. Current thinking is that this is a result of children with a genetic predisposition to obesity living in an obesogenic environment.However, studies have been finding increasing links between genetic factors and obesity. For a fuller discussion, see separate article Obesity in Adults.
A systematic review of countries in the European Union found evidence of a link between obesity and overweight in children and the socio-economic status of the parents, particularly the mother. Furthermore, the prevalence of childhood overweight is linked to the respective country's income inequality or relative poverty.
Public Health England child obesity factsheets suggest an almost linear relationship between obesity prevalence and deprivation.Children in the most deprived areas have almost double the obesity prevalence of those in the least deprived areas. Also, those children in households where the main wage earner has a professional occupation have lower rates of obesity than those who live in households where the main wage earner has a manual occupation.
The Millennium Cohort Study report at age 11 found no link with social class. It did, however, show a significant association with the level of parental education. In households where neither parent had educational qualifications, 25% of the children aged 11 were obese and 14% overweight, whereas in households where at least one parent held a degree, 15% of children were obese and 15% overweight.
Research conducted at Leeds Metropolitan University had different conclusions.The study, which involved a sample of more than 13,000 Leeds schoolchildren, concluded that children living in middle-affluent areas had the greatest probability of being obese. The study postulated that this group was most likely to indulge in 'snacking' between meals.
Some medication prescribed for children and adolescents may aggravate weight gain and the risks and benefits should always be considered. This includes:
- Antidepressants including mirtazapine, paroxetine, imipramine.
- Anticonvulsants including sodium valproate, gabapentin, vigabatrin and carbamazepine.
- Antipsychotics, especially the atypical antipsychotics aripiprazole, chlorpromazine, clozapine, olanzapine, pimozide, quetiapine, and risperidone.
Other risk factors
- High birth weight. Also low birth weight associated with catch-up growth.
- Intrauterine exposure to maternal gestational diabetes or maternal obesity.
- Timing or rate of maturation.
- Other behavioural or psychological factors.
- Physical conditions such as endocrine causes (rare):
- Cushing's syndrome - look for truncal obesity, hypertension, hirsutism.
- Growth hormone deficiency - there may be weight gain with delayed puberty.
- Muscular dystrophy and other causes of immobility.
- Polycystic ovary syndrome.
- Hypothalamic damage.
- Spina bifida.
- Genetic syndromes associated with hypogonadism (eg, Prader-Willi syndrome, Laurence-Moon syndrome, Bardet-Biedl syndrome).
Any gold standard for diagnosing obesity would be based on body fat content. Adiposity can be directly measured (by densitometry or dual-energy X-ray absorptiometry (DEXA) scanning) and indirectly (anthropometric measurements, bio-electrical impedance and air displacement plethysmography).This is not practical in primary care. In adults, BMI is often used. The problem with this approach is that it takes no account of factors which have a marked effect on growth in childhood, such as age, gender, puberty and race/ethnicity.
National Institute for Health and Care Excellence (NICE) guidelines recommend using the UK 1990 BMI charts to assess weight in children and young people.These are adapted charts based on 1990 UK population data for use from age 2 to 18. Up to the age of 4 years charts incorporate data from the WHO (known as the UK-WHO charts) but from age 4, UK 1990 data are used. The charts create centiles which are age- and gender-specific. Using these charts, a child with:
- A BMI over the 91st centile is classified as overweight.
- A BMI over the 98th centile is classified as obese.
- A BMI over the 99.6th centile is classified as severely obese.
The measurement of waist circumference is not recommended in children.
In the separate article Centile Charts and Assessing Growth, the problem of diagnosing childhood obesity is discussed more fully.
Raising the issue
Studies have shown that parents often have an incorrect perception of their child's weight.Charts may be needed to drive the message home. "Puppy fat" is a common excuse. Endocrine causes for childhood obesity are rare. It is worth stressing that obesity is a clinical term with health implications rather than just the way somebody looks.
It can be a delicate issue to raise with a parent and this may mark the (good or bad) start to a long therapeutic period. The issue may be raised:
- If the family expresses concern about the child's weight. Try: "We can measure [child's] weight and see if he or she is overweight for his or her age."
- If the child has weight-related comorbidities. Try: "[Condition] can sometimes be related to a child's weight. I think we should check [child's] weight."
- If the child is visibly overweight. Try: "I see more children these days who are a little overweight. Could we check [child's] weight?"
This may be the first time that weight has been raised with the family. It is a time to be reassuring and supportive. "By taking action now, we have a chance to improve [child's] health in the future."
Assessment should include the following:
- Height and weight should be in light clothing with no shoes. Establish BMI using UK 1990 charts.NICE recommends tailored clinical intervention if a child's BMI (adjusted for age and sex) is at the 91st centile or above and that assessment for comorbidities should be considered if their BMI is at the 98th centile or above
- Explore why help is being requested; is it the child or the family or are there comorbid problems? The child may have been flagged up during the course of the NCMP.
- Explore problems caused by weight, physical symptoms or distress caused by bullying, teasing or low self-esteem.
- Explore factors which might be contributing to weight gain, including:
- Social, environmental and family circumstances.
- Medication or medical problems.
- Roles of family or care workers.
- Explore motivation and willingness to change.
- Discuss what has already been tried and how successful it has been. Explore beliefs of the child and the parent(s) about weight, eating and physical activity.
- Perform a physical examination, looking for features of physical causes (see 'Other risk factors', above). If acceptable to the child, evaluate pubertal development.
- Test urine for protein and glucose.
- Check blood pressure; however, the cuff needs to be suitably sized.
- Consider measuring lipids and HbA1c.
- Rapid changes in BMI occur during normal growth; there is a great potential for reducing overweight in children and adolescents.
- Unless the child is seriously overweight or has significant comorbidities, be led by the child's/parent's wishes. Make decisions with the child and their parent(s), and tailor interventions to their individual needs and preferences.
- As children are still growing, the aim is often not weight loss but weight maintenance or even a reduction in the rate of gain of weight.
- Apart from the basic principle that energy intake should be reduced and energy output in the form of physical activity increased, there is little in the way of evidence to support any particular preventative approach.NICE recommends that school, family and societal interventions should be considered in the management and prevention of obesity in children. This may include involving parents in weight loss programmes. Ensure all interventions address lifestyle within the family and social settings.
- Encourage parents to take responsibility for any lifestyle changes, particularly for children under the age of 12.
- Multi-component interventions are the treatment of choice.
- The suggestion that inadequate sleep in children may aggravate obesity has been noted above. Ensuring adequate sleep may be important.
- Beware of potential underlying psychological factors. There may be 'comfort eating' or even clinical depression that needs treatment.
- Overweight adults need caring, compassionate and empathetic attention. This is even more important in children. Praise success at every occasion, however small.
Diet and exercise
The primary aims of management are dietary modification and the initiation of exercise. Losing weight without exercise is very difficult but the obese child may find it very tough taking exercise up initially.
- NICE does not recommend using a dietary approach alone.
- Tailor any dietary changes to individual preferences. Allow a flexible, individual approach.
- Do not recommend unduly restrictive, nutritionally unbalanced diets.
- It may be helpful to keep a food diary (assists cognitive approach). Do not forget snacks and drinks.
- It is very unpleasant being hungry and, rather than just cutting back on all food, it may be easier to move to a diet with less fat and more fibre in it.
- NICE advises that calorie intake should be below energy expenditure, but gives no specifics about diet or numbers of calories. It emphasises the general benefits of healthy eating.
- There may be occasions where there is benefit in referral to a dietician, particularly where there is a large amount of weight to be lost and caloric cut has to be balanced by adequate nutrition for ongoing developmental needs.
- This is not easy for the patient and it is important to be positive and reinforcing.
- The value of exercise is more than just the calories expended in the session. It tends to increase basal metabolic rate and, after vigorous exercise, metabolism is stimulated for the subsequent 36 hours. It has cardiovascular benefit, and reduces the risk of diabetes. It also promotes a sense of well-being.
- Overweight children often shun exercise because of poor mobility, ready fatigue and "being no good at games". It is important to discuss the options to find something appropriate and sustainable. The age and aptitudes of the individual must be taken into account. It must be something that the individual will enjoy or he or she will not persevere. This is very important, as the ethos of exercise is not just for the duration of weight loss but for life.
- NICE recommends a total of 60 minutes of at least moderate exercise each day (in one session, or more, shorter sessions lasting a minimum of 10 minutes). Overweight children may need more than 60 minutes.
- Exercise need not always be 'formal' - walking, using stairs, cycling and active play all count.
- Reduce time spent on inactive pursuits, such as watching television and playing video games.
- It is very helpful to involve all the family in development of an active lifestyle.[20, 21]
This is important and should accompany all the other approaches described above. It is as important in helping the individual understand the problem as it is to help them through treatment. Behavioural interventions require a trained professional and strategies supported by NICE guidelines include:
- Stimulus control.
- Goal setting.
- Rewards for reaching goals.
- Problem solving.
Parents should be encouraged to role-model desired behaviour. See separate article Cognitive and Behavioural Therapies which discusses behaviour modification.
- Orlistat is currently the only pharmacological intervention licensed for the treatment of obesity in the UK.
- Drug treatment is not usually recommended for children. Orlistat does not have market authorisation for use in children. A Cochrane review supports the use of orlistat in adolescents over the age of 12 as an adjunct to lifestyle changes, once the potential for adverse effects has been considered.Pharmacists will not issue over-the-counter orlistat to individuals under 18 years of age.
- In children over the age of 12 where there are physical comorbidities (such as orthopaedic problems or sleep apnoea) or severe psychological comorbidities, there may be a role for drug treatment after dietary, exercise and behavioural programmes have been started and evaluated.
- NICE does not recommend the use orlistat in children aged less than 12 other than in exceptional circumstances and under specialist care.
- Treatment should be initiated in a specialist paediatric setting, by multidisciplinary teams with experience of prescribing in this age group. It may be continued in primary care, if local circumstances and/or licensing allow.
- Regular monitoring of physical parameters, psychological factors, behaviour, diet and exercise should be part of the treatment package.
- If used, a trial of treatment for 6-12 months is advised.
- Consider supplementation with multi-vitamins.
The use of medication in children is continually being assessed and may well play an increasing role in the face of the obesity epidemic. One study found that metformin given to children or young people aged 8-18 caused a reduction in BMI and had a beneficial effect on insulin and glucose, alanine aminotransferase (ALT) levels and adiponectin to leptin ratio (ALR - a marker for cardiovascular risk).
Bariatric surgery is limited to the severely obese who are refractory to other management. In young people, it is generally not recommended but may be considered in exceptional circumstances if:
- Physiological maturity has been reached, or almost reached.
- The child or young person has had a full assessment for underlying treatable causes of obesity, including genetic screening.
- All appropriate non-surgical measures have failed to produce adequate results over six months.
- They have had a comprehensive psychological, educational, family and social assessment.
- They are receiving intensive specialist multidisciplinary assessment, treatment and support.
- They are fit for anaesthesia and surgery.
- They have a comprehensive follow-up package of care.
Bariatric surgery is associated with larger decreases in BMI and greater improvements of some metabolic markers but it is associated with considerable risks.See separate article Bariatric Surgery for more information.
As with any chronic disease, follow-up must be arranged. This implies interest in the patient's progress. Obesity is a chronic disease and needs to be managed throughout the person's life, as relapse is common. "Yo-yo dieting" with weight going up and down is undesirable and unhealthy.
Before referral to secondary care, consider referral to community-based treatment programmes such as MEND (mind, exercise, nutrition ... do it!) - the only programme provided nationwide in the UK.It runs various age-appropriate courses.
NICE public health guidelines promote the development of lifestyle weight management programmes in the community.
- BMI is above the 98th centile.
- There is serious morbidity related to the weight (eg, sleep apnoea, orthopaedic problems).
- There is a significant learning disability.
- The height is below the 9th centile, the child is unexpectedly short for the family or if there is a slowed growth velocity.
- There is precocious or delayed puberty (ie younger than 8 or older than 13 in girls and 15 in boys).
- There are symptoms/signs suggestive of an endocrine or genetic problem.
- There is severe or progressive obesity before the age of 2.
- You have other significant concerns.
- Insulin resistance and type 2 diabetes.
- Breathing problems - eg, sleep apnoea and reactive airway disease.
- Orthopaedic conditions.
- Non-alcoholic fatty liver disease.
- Psychosocial morbidity.
- Polycystic ovary syndrome.
- Metabolic syndrome.
- Vitamin D and iron deficiency.
There are then problems if these children carry their obesity into adulthood. There may be an increased future risk of impaired fertility, some cancers, atherosclerosis, early cardiovascular disease, hyperlipidaemia and hypertension. One study reported that retinol binding protein 4, a biochemical marker for comorbidity in adult obesity, could also be found in children.Another reported that two thirds of severely obese children had cardiovascular risk factors.
Currently, the UK National Screening Committee's policy is that there is not enough evidence available to recommend screening children for obesity, as few obesity prevention interventions have been shown to be effective in children.The policy is due for review and a working group has been set up. However, longitudinal observational studies in children have suggested that opportunistic monitoring of growth charts after 2 years of age may be beneficial. In 2005, an annual National Child Measurement Programme (NCMP) was introduced in England for surveillance (not screening) of two school year groups: Reception and Year 6. This information is collated by local NHS providers. In some areas, parents of children whose weight lies outside the normal range are sent a letter informing them of the results.
The English cross-government 'Healthy Weight, Healthy Lives' strategy in 2008 aimed to reverse the trend in rising childhood obesity so that levels return to those of 2000 by 2020. This led to the introduction of the Change4Life initiative which was launched in 2008. This aimed to improve children's diets and levels of activity.This was followed by the 2011 "Healthy lives, healthy people. A call to action on obesity in England" policy.However, two years later, the Royal College of Physicians issued a report criticising the Government's lack of progress in combating the obesity epidemic. They were particularly critical of the lack of facilities for children, who often do not qualify for medication or bariatric surgery. They have called for less variation in the provision of obesity services and leadership at all levels of NHS provision.In August 2014, the Royal College of General Practitioners (RCGP) wrote an open letter to the Chief Medical Officer for England, recommending that a national Child Obesity Action Group be set up as a matter of urgency.
The Royal College of Paediatrics and Child Health recently issued a position statement on childhood obesity. This identified many possible initiatives to combat the problem. The salient points were:
- An increase in training for health professionals.
- Encouraging breast-feeding.
- Extending the free school meals programme.
- Increasing the amount of moderate-intensity exercise undertaken daily by schoolchildren.
- Banning the advertising on television of unhealthy food before the watershed.
- Increasing the tax on unhealthy food.
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Further reading & references
- Child weight data factsheet; Public Health England (Oct 2015)
- Reducing obesity: future choices; Government Office for Science
- Friedemann C, Heneghan C, Mahtani K, et al; Cardiovascular disease risk in healthy children and its association with body mass index: systematic review and meta-analysis. BMJ. 2012 Sep 25 345:e4759. doi: 10.1136/bmj.e4759.
- Obesity; Royal College of Paediatrics and Child Health
- Kitsios K, Papadopoulou M, Kosta K, et al; High-sensitivity C-reactive protein levels and metabolic disorders in obese and overweight children and adolescents. J Clin Res Pediatr Endocrinol. 2013 Jun 31. doi: 10.4274/Jcrpe.789.
- Johnson W, Wright J, Cameron N; The risk of obesity by assessing infant growth against the UK-WHO charts compared to the UK90 reference: findings from the Born in Bradford birth cohort study. BMC Pediatr. 2012 Jul 23 12:104. doi: 10.1186/1471-2431-12-104.
- Spruijt-Metz D; Etiology, Treatment and Prevention of Obesity in Childhood and Adolescence: A Decade in Review. J Res Adolesc. 2011 Mar 21(1):129-152.
- NDR (Nutrition and Diet Resources) UK
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