The 21st century has brought advances in technology and science. Adults and children alike now spend hours navigating the Internet, watching TV and playing Nintendo. It has become a common treat for our children to eat out at a fast-food restaurant, where a supersized cheeseburger and a sugar-loaded soda can be purchased for just a couple of extra dirhams. Add to this mix physical inactivity and genetic predisposition, and the result is an epidemic of obesity, the rate of which has increased at an alarming rate over the past two decades. Across the world, 20-40% of adults and children at any given time are either overweight or obese.
What is obesity?
Obesity is defined by relating an individual’s weight to their height. The most commonly used method is by working out their Body Mass Index (BMI). BMI is calculated by dividing a person’s weight in kilograms by the square of their height in metres. For example, a person with a weight of 80 kg and height of 1.8 metres will have a BMI of: 80/ (1.8)2= 24.7 kg/m2. Being overweight is defined as having a BMI of above 25 and obesity is a BMI of 30 or over. A BMI of 40 or over in adults is considered to be severe (or morbid) obesity.
Although the same formula can be applied to children, it is more accurate to relate the BMI value to the gender-adjusted weight and height in a particular population, as these values may also be affected by the ethnic background of the child. If the BMI of a child is 95% or over of children from the same ethnic background, age and gender, he or she is considered obese. If it is over 85-95%, he or she is deemed to be overweight. The growth charts shown below were developed in 2000 by the Center of Disease Control and Prevention in the USA. They are used in many countries of the world, including the UAE (Figure 1). Similar charts are also produced by the World Health Organisation (WHO).
The scope of the problem in children
The increased prevalence of childhood obesity parallels that seen in adults and current research indicates that the majority of obese children will become obese adults. Each year an estimated 300,000 American adults die of obesity-related causes and the direct cost of obesity and physical inactivity consumes 9.4% of U.S. health care expenditure. About 19% of American children between 6-11 years of age are overweight and similar data are reported from European countries.
Obesity in the UAE
In the UAE, the statistics are scary. In 2000, the WHO estimated that 34% of adults in the UAE are obese and 20% have diabetes, one of the most serious complications of obesity. In the same year, a survey conducted in 4,000 schoolchildren in the UAE between 6-16 years of age found that 25% were either overweight or obese. The Global School-based Health Survey, which was sponsored by the WHO in 2005, studied more than 15,000 children in 194 schools in the UAE. It showed the number of children who are obese or overweight to be up to 34%; a striking increase of 2% per year.
Complications of childhood obesity
There are numerous health complications for obese children who grow into obese adults (Table 2). Obesity in children increases the risk of adult coronary heart disease (CHD). The process of depositing fat into the blood vessels (atherosclerosis) starts in young children and continues into adulthood (Figure 2). Fatty accumulations in the vessel wall, especially in the coronary arteries (blood vessels which feed the heart), is evident as early as 6 years of age. Progressive fat accumulation in the vessel wall ultimately results in a thick plaque, which narrows the blood vessel and can interrupt or stop the blood supply to the heart or brain, resulting in either a stroke or heart attack. Such plaques are seen in 10% of young children and nearly 70% of adults.
Even foetuses carried by mothers who have high cholesterol show fatty deposition in their blood vessels before they are born. A study published in 2007 in the New England Journal of Medicine looked at 277,000 Danish children born between 1930 and 1975, following them for more than 25 years. The study found that there was a strong association of an individual’s BMI as a child and his/her risk of developing CHD in the future. Up to 16% of children aged 7-13 years who were overweight by 4-12 kg developed a heart attack by the age of 60. As such, for a 13-year old boy overweight by 11 kg, the risk of developing CHD was increased by almost 1/3. A British study of 2,400 children between the age 2-14 years showed a strong correlation between increasing BMI and death from CHD later (other complications of obesity are listed in table 2 below).
Metabolic Syndrome in children
Obese children can develop hyperlipidaemia (high cholesterol), diabetes (high blood sugar) and hypertension (high blood pressure). Such group of abnormalities is called ‘metabolic syndrome’ and is present in nearly 1 in 4 obese adults and children. About one third of children with metabolic syndrome develop hypertension and/or diabetes, increasing their risk of atherosclerosis. Both hypertension and diabetes lead to faster damage to the blood vessels and earlier and more serious heart attack or stroke. This is in addition to the damage occurring to other body organs, including the kidneys, nerves, and eyes. A recent study found that 44% of obese children in the UAE have metabolic syndrome.
Prevention: the key to success
In the short term, children who already have developed obesity need to be diagnosed and treated early. The treatment involves adopting a healthier lifestyle and in some cases by using medication. There are numerous recommendations from international authorities for early diagnosis, prevention and treatment of obesity-related complications (Table 3). Prevention starts as early as before birth, with the mother adopting a balanced diet during pregnancy. After birth, breast feeding remains the best preventive tool to decrease the chance of obesity in childhood and in later life. A study of adults born in the 1950s showed a decreased risk of obesity and metabolic syndrome in those who were breast-fed for at least one month. Throughout childhood, maintaining a balanced diet, decreasing fat intake and limiting the amount of ‘junk’ food and sugar-soda is the key. Obese schoolchildren in the UAE eat more snacks between regular meals (most of which are fried snacks, rather than fruits and vegetables), eat school meals rather than home-cooked meals and consume more servings of soda. One extra serving of regular soda (which contains 120 calories per serving) can produce a 50 kg increase in body weight over 10 years. A study published in The Lancet in 2001 showed that such habits increase the chance of childhood obesity by 60%.