Obesity in Children

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 such as atherosclerosis, start early in life and are accelerated by obesity. It is feared that the current generation of children may be the first generation for centuries in whom their life expectancy will be less than their parents. Considering how life expectancy rose over the 20th century, this is a substantial reversal.

• The Health Survey for England 2002¹ states that 16% of boys and girls aged 2 to 15 are obese with a total of 30% classified as either overweight or obese. A third of young adults are either overweight or obese (32% of young men and 33% of young women). In addition, 9% of young men and 12% of young women are actually obese.
• Several factors have now been shown to predict the development of obesity in individuals such as a family history of obesity, lifestyle, diet and socioeconomic factors.²

Any gold standard for diagnosing obesity would be based on body fat content. This is not easy to estimate and in adults body mass index (BMI) is used although it fails to take into account those who are very muscular. BMI per se is not a suitable way to assess obesity in children. In the article on centiles and assessing growth, the problem of diagnosing childhood obesity is discussed. BMI can be used provided that it is moderated by use of the UK90 charts³ or the like. A child with a BMI of 20 is significantly overweight and the younger the child, the more this is so.

Parents can be remarkably obtuse in noting that a child is overweight and charts may be needed to drive the message home. "Puppy fat" is a common excuse or assertions that "it's his glands that's the problem." This usually means overactive salivary glands as endocrine causes for childhood obesity are rare. Fat children tend to be tall but centile charts may show that a child is on the 75th centile for height and the 97th centile for weight. This much higher centile for weight than for height, suggests obesity. If a fat child is not tall, refer to a paediatrician.

There is no evidence based guideline for the treatment of obesity in children, but SIGN makes the following recommendations:⁴

• BMI centiles should be used to identify childhood obesity, obesity being ≥98th centile of the UK 1990 reference chart for age and sex. Overweight is defined as ≥91st centile.
• The value of waist circumference in children is unknown and so measuring it is not recommended.
• School, family, and societal interventions should be considered for the prevention of obesity in children.

There are numerous factors that are thought to contribute to this trend. Children are more often driven to school rather than walking or cycling. Compulsory sport is in decline. Bad eating habits develop with a taste for junk food that is high in fat and fast carbohydrates. Working mothers and a decline in family meals may contribute. Another contributory factor that has been suggested is sleep deprivation. Presumably there has been a trend of children going to bed later, perhaps watching more television in the evenings or playing computer games. Another possibility is that lack of physical activity leads to poor sleep.⁵ 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.⁶ Both these would encourage an individual to eat more. Many doctors will have noted, from personal experience, that after a night of sleep deprivation, that a good breakfast helps one to face the forthcoming day.

A review has examined predictors of childhood obesity.⁷ Risk factors for obesity include parental fatness, social factors, birth weight, timing or rate of maturation, physical activity, dietary factors and other behavioural or psychological factors. The relative contributions of genes and inherited lifestyle factors remain largely unknown. No clear relationship is reported between socio-economic status (SES) in early life and childhood fatness. However, a strong consistent relationship is observed between low SES in early life and increased fatness in adulthood. Women who change social class (social mobility) show the prevalence of obesity of the class they join, but this is not true of men. Studies investigating the role of diet or activity were generally small, and included diverse methods of risk factor measurement. There was almost no evidence for an influence of activity in infancy on later fatness, and inconsistent but suggestive evidence for a protective effect of activity in childhood on later fatness. No clear evidence for an effect of infant feeding on later fatness emerged, but follow-up to adulthood was rare, with only one study measuring fatness after 7years.

Genetic factors have been discussed in Obesity - The Size of the Problem. Just because obesity runs in families, this does not mean that it is genetic and it certainly does not mean that it is impossible to do something about it. Families eat together. They develop a common attitude towards food. The diet may be high in fat. Large, high calorie meals may be normal and everyone is expected to clear the plate. In some families the provision of sweets and cakes is an index of love. Being at risk of obesity does not make obesity inevitable. It means that the individual has to work harder to maintain an acceptable weight. Obesity is multifactorial.

• 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.
• Fat children often like to opt out of sport and tend to prefer sedentary activities. Encourage activity and try to find a form that they like. They may be less disadvantaged at swimming but the attire shows every bulge.
• SIGN recommends sustained behavioural changes including healthier eating, a minimum of 30 minutes per day of physical activity and reducing inactivity such as television or computer games to less than 2 hours a day.
• The suggestion that inadequate sleep in children may aggravate obesity has been noted above. Ensuring adequate sleep may be important.
• Overweight adults need caring, compassionate and empathetic attention. This is even more important in children.

There is much in the management of children that is common to management of obesity in adults. The following should be included in a plan of action:

• Identify the causes that have made the child obese. There are probably several contributory factors.
• Check how the child feels about his weight. Does he feel that it is a problem? Does he want to do something about it? He is the one who will have to do the hard work of loosing weight. Have there been previous attempts at weight loss and if so, what happened? What went wrong?
• Reiterate why the child wants to lose weight to emphasise potential benefits and incentives and perhaps to ascertain the degree of motivation.
• Examine what can be done to facilitate weight loss.
• Set realistic targets for rate of loss of weight and desired end point.

The article on cognitive and behavioural therapy discusses behaviour modification. Basically, it involves helping the patient to identify attitudes and actions in their lives that have caused the problem, to understand why they need to be rectified, to identify appropriate responses and to implement them. There may be "comfort eating" or even clinical depression that needs treatment. A child who is being sexually abused may be trying to become ugly and undesirable.

The 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 unattractive.

This is not easy for the patient and it is important to be positive and reinforcing.

Cognition

The first problem may be to convince the patient and parent that he is eating too much. It is important to explain that the equation about calories in and calories out has no exception. Only a negative calorie balance will result in weight loss. It may be helpful to ask the child to keep a food diary, including all snacks taken during the day.

Dietary History

The food diary will be over perhaps a week and will reflect a typical day's intake. Do not forget snacks, sweets and treats. Do not forget drinks. There may be obvious targets for modification. Replace sugar by sweeteners or try to do without them. Use skimmed rather than full fat milk.

Diets

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. Losing weight is hard and takes tenacity. As with adults, herbal and "natural" wonders are also to be avoided as are diets promoted by "celebrities".

There may be occasions where there is benefit in referral to a dietician. If more than a tiny fraction of obese people within the catchment area are referred, it would swamp the service but children who are significantly overweight may be regarded as a special group.

Times of Meals

Those who advise about diet almost invariably counsel that breakfast is the most important meal of the day and those who do not have breakfast should introduce it. Eating late at night is bad as the food rapidly turns to fat. This may be true but the evidence for these assertions is limited at best.

Fat 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 will not persevere. This is very important as the ethos of exercise is not just for the duration of weight loss, that is a very long process, but for life.

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 next 36 hours. It also helps people to feel good about themselves. When people start to diet, weight often falls away quite fast at first but the rate of loss then tails away, causing dismay. When people start exercise, weight loss may be slow and disheartening at first as muscle is built, and with it bone for a stronger skeleton. Hence, weight being static may represent fat being replaced by muscle.

The drug management of obesity is discussed much more fully elsewhere. Sibutramine has been reviewed by NICE,⁸ as has orlistat.⁹ The NICE guidelines also outline the limited indications for prescription. Neither of these drugs is licenced for use below the age of 18 because of limited data from trials. It is possible that a paediatrician may feel, with his expertise, that there is a case for one of these drugs in an individual case. Prescribing off-licence requires care and expertise. For the generalist, it is a route best avoided.

There are a number of drugs that aggravate weight gain¹⁰ and if the patient takes them, it may be advisable to consider an alternative. Most of such drugs would not be prescribed for children.

• Antidepressants including tricyclics, mirtazapine, monoamine oxidase inhibitors.
• Anticonvulsants, particularly sodium valproate, gabapentin, vigabatrin.
• Antipsychotics, especially the atypical antipsychotics amisulpride, aripiprazole, clozapine, olanzapine, quetiapine, risperidone, and zotepine.
• Corticosteroids.

Bariatric surgery is considered elsewhere and has also been reviewed by NICE.¹¹ It is limited to the severely obese who are refractory to other management. There have been reports in the mass media about its use in teenagers. The public response has often been irrational but these are individuals whose obesity is a life-threatening condition and they have not responded to other methods.

As with any chronic disease, follow up must be arranged. This implies interest in the patient's progress. A fortnight to a month would be appropriate at first, with intervals getting longer with time but treat it as a chronic disease. The practice may have a nurse run weight control clinic.

The achievement of a target weight is not the end of the process. 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.

A study from Finland¹² suggested that the standard risk factors for arterial disease, as applied to adolescents, predict evidence of atherosclerosis at an early age. This has also been confirmed from a multiracial study in New Orleans.¹³ In the young, there is a correlation between the intensity of exposure to risk factors such as cigarette smoking, hypertension, dyslipidaemia and diabetes mellitus and the extent and severity of arterial fatty streaks or raised plaques.¹⁴ Obesity does not come alone but is often accompanied by lipid abnormalities and possibly diabetes. The incidence of childhood obesity is such that we are seeing type 2 diabetes in adolescents. This is called MODY (maturity onset diabetes in the young). All the traditional predictors of atherosclerosis, including obesity and the consequent metabolic derangements, do seem to predict early arterial disease.¹⁵

It is often assumed that fat children will evolve into fat adults and they have little chance of overcoming their obesity whilst the risk factors associated with obesity will be accentuated by having started so early in life. This assumption may not be supported by the evidence. The thousand families study traced a cohort who were born in 1947. The study from Newcastle¹⁶ traced 932 people, of whom 412 were examined at age 50. The study concluded that when using a measure of fatness that was independent of build, there was little association between obesity in childhood and adulthood. Only children who were obese at 13 showed an increased risk of obesity as adults. No excess adult health risk from childhood or teenage overweight was found. Being thin in childhood offered no protection against adult fatness, and the thinnest children tended to have the highest adult risk at every level of adult obesity.

Another study took a cohort born in 1970 to assess the effect of childhood obesity on adult socioeconomic, educational, social, and psychological outcomes.¹⁷ Of the 8,490 participants with data on body mass index at 10 and 30 years, 4.3% were obese at 10 years and 16.3% at 30 years. Obesity limited to childhood has little impact on adult outcomes. Persistent obesity in women is associated with poorer employment and relationship outcomes. Efforts to reduce the socioeconomic and psychosocial burden of obesity in adult life should focus on prevention of the persistence of obesity from childhood into adulthood.

Of that same group, 8.2% were obese at 16 and 16.4% were obese at 30. Of those who were obese at 16, just over 60% were also obese at 30.¹⁸ Hence, obesity in youth must be seen as a strong risk for adult obesity but more than a third of those who were obese at 16 had conquered it at 30.