A condition in which a child is severely overweight
- Slightly more common with increasing age
- Sometimes runs in families; occasionally associated with certain genetic diseases
- Overeating and a sedentary lifestyle are risk factors
- Gender is not a significant factor
The number of overweight and obese children has increased steadily over the last two decades, and it is now estimated that about 1 in 5 children in the UK is obese. As with adults, obesity in children is assessed using body mass index (BMI) values. An individual’s BMI is his or her weight (in kilograms) divided by his or her height (in metres) squared. Unlike in adults, there is no single BMI value that can be used to define overweight or obesity in children. Instead, percentiles are used; this is method of assessment that is based on the percentage of people (in this case, children) that is above or below a particular value (in this case, has a higher or lower BMI). A child is defined as obese if his or her BMI is above the 98th percentile, which means that his or her BMI is higher than that of 98 per cent of children of the same age. A child is considered overweight if his or her BMI is between the 91st percentile (i.e. 91 per cent of the same-age children have a lower BMI) and the 98th percentile (98 per cent have a lower BMI).
What are the causes?
By far the most common cause of childhood obesity is an unhealthy, high-calorie diet combined with lack of physical activity. Although childhood obesity sometimes runs in families, this is usually because of an unhealthy family lifestyle. However, in very rare cases, there may be a genetic cause for obesity, as in Prader–Willi syndrome, an inherited genetic abnormality that leads to compulsive overeating. Very occasionally, other medical conditions may also cause obesity, such as underactivity of the thyroid gland (see Hypothyroidism) or a brain tumour.
Are there complications?
During childhood, obesity may lead to a wide variety of health problems, including type 2 diabetes (see Diabetes mellitus); high blood cholesterol levels; high blood pressure (see Hypertension); and digestive system disorders, such as abdominal pain, gallstones, inflammation of the gallbladder (see Cholecystitis), inflammation of the pancreas (see Acute pancreatitis), and liver disease. The excess weight causes increased stress on the musculoskeletal system, which may lead to bone and joint problems, such as bow legs (see Minor leg and foot problems) or slipped femoral epiphysis. Accumulation of fat around the airways may cause respiratory problems such as asthma and obstructive sleep apnoea In some adolescent girls, obesity may also be associated with hormone-related problems, such as early onset of puberty, acne, menstrual irregularities, excessive body hair, and polycystic ovarian syndrome. As well as physical problems, obesity may also cause emotional and psychological problems, such as depression or eating disorders.
Children who are obese are more likely to be obese as adults and are therefore at increased risk of developing the numerous disorders associated with adult obesity (see Obesity in adults).
What might be done?
The whole family should eat a healthy, balanced diet, with plenty of fruit and vegetables and fresh, home-made food. Fast food, high-calorie snacks, and fizzy drinks should be avoided. You should encourage your child to take plenty of physical exercise, and consider limiting your child’s time using a computer or watching television. It is better to reward healthy eating and exercise rather than punishing unhealthy habits. You should aim for a gradual return to a healthy weight, not a dramatic weight loss.
If these measures do not seem to be working or if you are concerned about your child’s weight, you should consult your doctor. He or she will calculate your child’s BMI, and will carry out a thorough examination to look for any signs of obesity-related disorders. The doctor may also perform tests to check for any underlying disorder that might be a cause of the obesity.
If an underlying causative disorder is found, treatment for the disorder will probably also lead to weight loss. However, in most cases, the cause is simply an unhealthy lifestyle, and the doctor will probably refer you to a dietitian and possibly other specialists, such as a child psychologist and physiotherapist. Occasionally, the doctor may recommend family therapy for all the family members.
Other treatments, such as anti-obesity drugs or surgery (for example, a stomach bypass or gastric banding) are only recommended in exceptional cases for older children when all other possibilities have failed and the child remains extremely obese and has obesity-related health problems.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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