Literature Review - A 21st Century Epidemic: Childhood Obesity in North America

Author:  Nafisa M. Jadavji
Institution:  School of Health Sciences, University of Lethbridge, 4401 University Drive West, Lethbridge, AB T1K 3M4 CANADA
Date:  August 2006


Fat has been termed the "new tobacco" by the Canadian Heart and Stroke Foundation, because of the high general risk of an individual eventually becoming obese. This review will discuss the cause and effect of childhood obesity as well as compile recommendations and initiatives currently in place to decrease childhood and adult obesity. For children of the 21st century, obesity is one of the most common metabolic and nutritional diseases. Healthcare professionals can measure the percent of body fat in children by using Body Mass Index (BMI). Specifically, for children and BMI that is age and gender specific can be used to take measurements of the percent of body fat. Researchers have identified three main causes of obesity and they include genetics, overeating and lack of exercise. The effects of obesity on children have a huge impact and can range from low self-esteem to increased risk of cardiovascular diseases. The most effective cure for childhood obesity is prevention. Parents and healthcare professionals can work together to make prevention more effective and one day perhaps abolishing this epidemic.


The American Heritage Dictionary formally defines obesity as condition of increased body weight that is caused by an excessive accumulation of fat. Obesity has been termed the new epidemic' in both adults and children. In 1998 the World Health Organization (WHO) designated obesity as a global epidemic (Anrig, 2003). The combination of increasing high fat foods in out diets and low physical activity, it is very easy to become overweight or obese in today's society. The cost of obesity in Canada over the past twenty years has tripled. Currently, the cost is one hundred and twenty-seven dollars per year per person in Canada (Double check). Studies have shown that obesity has killed more people than AIDS. However, insurance companies rarely cover any costs that are associated with treatments for obesity (Kempster, 2003). The purpose of this paper is to discuss the increasing epidemic of childhood obesity in North America and its implications. The following sections will describe: (1) mechanism of obesity, (2) causes of obesity, (3) measuring obesity, (4) preventing obesity, (5) possible recommendations and future directions.

Mechanism of Obesity

During growth, fat cells increase in number and when energy intake exceeds expenditure, fat cells increase in size. When fat cells have reached their maximum size and energy intake continues to exceed energy expenditure, fat cells increase in number again. With fat loss, the size of the cells shrinks, but not the number. When fat loss occurs, none of the cells decrease in number they only decrease in size (Whitney & Rolfes, 2002).

There are few fatty acids that occur in food or in our body and are often incorporated in the form of triglycerides, which are found in highly fatty foods. Triglycerides are composed of three fatty acids attached to a glycerol molecule. To make triglycerides, a series of condensation reactions take place with fatty acids combining with a hydrogen atom to from the glycerol, and a hydroxyl group to form a fatty acid, releasing a molecule of water. Triglycerides have recently become popular, since they extend the shelf life of many food products by protecting them against oxidation. A disadvantage of triglycerides is that they make poly-saturated fats more saturated. Therefore, any health advantages of using poly-saturated fats is lost during the process of hydrogenation and textures of foods are also altered (Whitney & Rolfes, 2002).

Research has shown that obesity is also associated with increased levels of a hormone called leptin (Moran et al., 2003). Leptin is secreted from adipose (fat) tissue and is involved in the regulation of food intake, energy expenditure and energy balance in humans (Moran et al., 2003; Whitney & Rolfes, 2002). In children today, obesity is the most common metabolic and nutritional disease, where as thirty years ago, obesity was rarely seen in children. In the past twenty years, there has been an exponential increase in the incidence of obesity among children. A study done by Tremblay et al. (2000) showed that there was a 17% increase in obesity rates among boys and a 15% increase among girls, since 1981 to 1996. This alarming increase in childhood obesity has been occurring in all westernized countries, and specifically in Canada. While childhood obesity rates were similar to other countries like Scotland, England and Spain in early 1980's, by the 1990's Canadian rates rose by leaps and bounds (Canadian Press, 2003).

Causes of Obesity

According to Dr. Peter Nieman, (2004) a practicing pediatrician, has identified three main causes of childhood obesity: genetics, overeating and lack of exercise. He emphasizes that it is important to understand that the causes of obesity are often a combination of these three factors. Obesity if just not the result of a single factor.


Genetics can contributes to obesity, but very rarely. Only one percent of obesity is due a hormonal cause (Nieman, 2004), that is, mutations that lead to altered secretion of hormones or hormonal action. Usually with the right support and guidance, children can work hard to keep their weight within a healthy range.


Overeating is another factor that causes obesity. Over the past fifteen years the super-sized portions are increasing, along with super-sized kids with super-sized problems (Kempster, 2004). Many areas of a child's life are influenced by this increase in overeating. For example, there have been dramatic changes at school that have helped kids make more unhealthy food choices. Cafeterias now serve food with larger fat content and low nutrition. Soda and candy machines have also been conveniently placed in many schools (Kempster, 2004). A recent study in the Journal of Pediatrics showed that fast-paced consumption results in a greater intake of fats and calories and decreased intake of foods and vegetables. A study done by King et al. (1999) showed that the percent fruit and raw vegetables grade six children consumed steadily declined from 1990 to 1998. For any given meal, at least 30% of kids are eating fast food and are eating approximately 200 more calories more, which adds up to 6 pounds of fat per year. Many researchers have argued that children should be protected from these damaging forces. However, they are exposed to these fast food choices everyday, making it difficult to support healthy eating (Kuntzman, 2004). In a recent press release, Burger King's CEO, Brad Blum told the public how Burger King would help reduce childhood obesity, "we hope to reinforce the importance of physical fitness as part of everyday life, help kids fuel the fire within and understand the concept of energy in and energy out" (Kuntzman, 2004). However, no campaign to date has been launched with this goal in mind.

Lack of Exercise

The third factor that causes childhood obesity is not getting enough exercise. This lack of activity is a result of the lack of emphasis on physical education in schools and at home. More specifically, there has been a decline in the development of grass root sports and a general decrease in the amount of time during and after school that is devoted to physical activity (Anrig, 2003). It has been shown by Tremblay et al. (2003) that organized and unorganized physical activity is negatively associated with obesity. Physical activity decreases the risk of a child becoming obese by at least 23% to 43%. In contrast, watching television and playing video games increases the risk of becoming overweight by 17% to 44% and becoming obese by 10% to 61%. In the 21st century, physical activities such as jumping rope, riding bikes, and skating have been replaced with television, video games and computer games (Anrig, 2003; Kempster, 2004).

Television viewing has been proven to be a significant factor in childhood obesity, since viewing during childhood years could have lasting effects on lifestyle later in life (Hancos et al., 2004). According to the Heart and Stroke Foundation of Canada, almost one in four Canadian children, between the ages of 7 and 12 are obese because television viewing encourages a sedentary lifestyle and also contributes to childhood obesity by aggressively marketing junk food to young audiences (Media Awareness, 2004). Canadian Pediatric Society found that most advertisements on children's TV shows are for fast food, candy and pre-sweetened cereals. Commercials for healthy food make up only 4% (Media Awareness Network, 2004). The average Canadian child spends at least 25 hours per week watching television (Oxford Count Board of Health, 2003). A study done by King et al. (1999) claims an increase of two more times a week from 1990 to 1998 and this decrease in physical activity is occurring at an alarming rate. Children's caloric intake is steadily increasing and at the same time there is a steady decrease in physical activity, because more time is spent playing video games and computer games. This also explains why the obesity rates are increasing faster amongst boys than girls in Canada (Canadian Press, 2003). In addition, cycling or walking are means of transportation to school that are no longer emphasized by parents of today, because children can take the bus or are driven. The replacement of many physical activities by technology has helped childhood obesity rates increase to make obesity the latest "epidemic" of industrialized nations, such as Canada and the United States.


Some other causes of obesity that were identified by researchers include sex, socio-economic status and race. In Canada, there is an increased risk of childhood obesity as you move from the west to the east coast (Willms et al, 2003). Childhood obesity has been shown to be less pronounced in Western Canadian provinces when compared to the Eastern Canadian provinces (Canada Press, 2003). Researchers have suggested that socio-economic status is inversely related to prevalence of being overweight (Willms et al., 2003). The risk of becoming overweight is more related to provinces than to demographic variables, such as income and family background. Researchers have also identified that secular trends exceed the effect of geographic or demographic variables (Willms et al., 2003).

A study done by Willms et al (2003) showed that parents' weight also plays an important factor in the causes of obesity. A 1998 study in the New England Medical Journal showed that if parents' weights are normal or slightly overweight when the child is between the ages of one and three, there is no increased risk of obesity later in life. However, children between the ages of one and three whose parents, brothers or sisters that are also overweight have a higher risk of becoming overweight themselves (Nieman, 2004).

Today, teachers and parents reward children with special foods and treats and children for the most part will choose the unhealthier alternative over the healthy alternative. An explanation for this behavior is that taste buds are programmed for sweet, salty or greasy foods and in the past these kinds of foods were not available as they are now (Kempster, 2004). A final cause of obesity identified by Dr. Spence (2000), a practicing physician is that today society is so obsessed with academic achievement that we as a society are producing a fat and drug dependent generation. The are many causes of childhood obesity and only few have been discussed, new and more advanced causes of obesity appearing everyday.

Measuring Obesity in Children

A child's bodyweight is regulated by numerous physiological mechanisms that maintain a balance between energy intake and expenditure (Bentivegna, 2004). Body mass index (BMI) is used to asses 3 measurements. These include underweight measurements, overweight measurements and risk for becoming overweight. Children's percent of body fatness changes over the years as they grow. Girls and boys also differ in their body fatness as they mature and that is why BMI for children (also referred to as BMI-for-age) is gender and age specific. Each BMI-for age and gender specificity contains percentiles. Healthcare professionals use these established percentiles as the cutoff points to identify underweight and overweight. This is a useful tool because it provides a reference for growing children and adolescents that can be used beyond puberty. In addition, BMI for age and gender compares well to laboratory measures of body fat and it can be used to track body size throughout life.

Effects of Obesity

Healthcare professionals and parents are just realizing the effects of childhood obesity. In 1997, the Canadian Medical Journal revealed that the cost of obesity amounted to 1.8 billion dollars in Canada. The high incidence of obesity causes increased blood pressure, diabetes and also increased levels of low self-esteem and depression in the population (Neiman, 2004). Low self-esteem and depression do not seem to be a direct effect of obesity, but Dr. Neiman (2004) points out that obese children might have many social and physiological problems. For example, many children who are obese are also often teased and ostracized because of their weight. A recent study has found that obese boys are four times as likely to suffer from depression when compared to their thinner peers. Researchers have shown that discrimination against fat kids begin as early as kindergarten (Patridge, 2003). The Journal of Medical Association has also shown that obese children consider their quality of life "significantly impaired" to the same degree as children being treated for cancer (Partridge, 2003).

Obese children and teenagers have a greater chance of becoming overweight adults (Anrig, 2003). It has been shown that children that are obese at the age of four have a twenty percent possibility of developing adult obesity and those who are overweight during adolescence increase their risk of developing adult obesity to eighty percent. The increase in the number of obese adults may put these individuals at a higher risk factor for adult morbidity and mortality (Anrig, 2003). The increase in weight among children and teenagers has caused an elevation in the prevalence of chronic disease like type II diabetes, coronary heart disease, insulin resistance, impaired glucose tolerance, menstrual irregularity, and hypertension. Other complications include asthma and obstructive sleep apnea among children (Nieman, 2004; Canadian Press, 2003; Anrig, 2003). It has been shown that more than 60% of overweight kids have at least one additional risk factor for heart disease and that more then 85% of kids are diagnosed with type II diabetes are obese or overweight (Partridge, 2003). At one point in time, type II diabetes and heart disease were thought to only affect adults. However, these diseases are now appearing in the adolescent population. This is particularly frightening because the next generation of adults who will enter adulthood will already have a lot of health problems because of their childhood obesity (Canadian Press, 2003).


Health care professional have published many preventative recommendations for parents, teachers, school administrators, and officials indicating ways to reduce obesity among children in Canada. Dr. Peter Nieman (2003) suggests that pediatricians should evaluate child's growth on a regular basis by calculating their BMI. This method can be used to monitor any abnormal increased in weight. BMI is very appropriate for assessing skin fold thickness (Felman et al., 1994). If a child's BMI exceeds the 85th percentile, then that is an indication that they are overweight and if his or her BMI exceeds the 95th percentile, then that indicates that the child is severely overweight. Monitoring of the BMI needs to start before the age of three and continue on a regular basis in order for any abnormal growth to be detected right away. This recommendation can be incorporated into prenatal and child health programs without any huge increase in costs. In order for this to be effective, there needs to be a coordinated effort of policy makers, health professionals, researchers, community leaders, school administrators and parents (Ball et al., 2003). Canning et al. (2004) have shown that intervention is not successful once the excessive weight gain and obesity have occurred. It is important to establish an age at which unhealthy body weight begins to emerge (Canning et al., 2004).

Other general recommendations for preventing childhood obesity include exercising, which can help maintain an ideal bodyweight, but there has been some mixed evidence about the role of exercise in weight loss in children (Feldman et al., 1994). There are many possible negative effects, for example stunting growth of bones. Breastfeeding has been shown to decrease the risk of obesity, for example moms that breast feed for three to five months after their child's birth, and their child is at 35% lower risk of obesity between the ages of five and six (Anrig et al., 2003). Researchers have also suggested that activity programs be reinstated in schools (Kempster, 2004). Adults need to control the time their children spend in sedentary activities and parents should become role models for the children by participating with their kids in activities like biking, walking, hiking or swimming to increase their child's interest and by eating healthy, well-balanced diets and promoting a healthy pattern of eating for the entire family (Oxford County Board of Health, 2002). Parents could teach children about eating the right foods and show them that it can be fun to eat a variety of fruits and vegetables by helping them pack their own lunches. Researchers have also suggested that parents and teachers should never use food as a reward or withhold food as a punishment; this may trigger the child to want the food even more (Oxford County Board of Health, 2002).

Kids love variety, so that needs to be incorporated into physical activities. This can be done by making them interesting and social by inviting friends and neighbors to join in. Dr. Des Spence (2004) created three core themes for a possible preventative strategy that would potentially reduce childhood obesity. His three cores are as follows. First, create safe cycle paths and walking paths to school and insist that parents walk their children to school in all weather conditions. Secondly, have one hour of competitive mixed team sports a days from primary school onwards. Lastly, give healthy free school lunches to all, which would mean that children would eat because no alternative would be offered. Cooking lessons for primary children should also become compulsory. Dr. Spence believes that a trial for one year would undoubtedly have a dramatic impact on obesity, fitness and conduct disorders.

Prevention of childhood obesity can begin prior to conception. This can be done by educating future parents of the risks of high birth weight, maternal diabetes and obesity among family members (Anrig, 2003). The best way to prevent childhood obesity is to teach children to eat less food that are high in fat by restricting intake of things like sweetened drinks, which are readily available in Canada (Medbroadcast, 2003). Children should be taught that being physically active on a regular basis is a good thing and that watching television is not (Renders et al., 2004). Experts say that children require one hundred and fifty minutes of active physical activity every week (Mediabroadcast, 2003). Prevention can be looked at as a cure, if proper leadership is in place and if there is effective communication (Renders et al., 2004).

There have been some programs that have been created and implemented to help decrease the rate of obesity among children. For example, some health care professionals have created a program called "Take Charge" (Passehl et al., 2004). This training program is delivered by healthcare professionals and provides education for parents on how to prevent obesity among their children and also how to encourage them to develop healthy lifestyles. This program has focused on abolishing the conventional intervention response, such as, to change the behaviour of overweight children.

Restricting or controlling the food that they take in is also important. However, when parents attempt to control a child's eating behaviors, the child is more likely to start to eat too much and too rapidly and they may begin to hide, sneak or crave those foods that they are been denied. This cycle is endless and the only way it can be broken is to have set boundaries for both the parent and child. For example, the parents are responsible for planning meals and snacks, preparing food and providing a supportive atmosphere and maintaining limits on grazing between meals and snacks. Children are responsible for whether they eat or not and how much they want of the good provided by their parents (Satter, 1996). The "Take Charge" program content embraces the need to avoid restrictive approaches in eating behaviors, since such approaches may actually increase risk of obesity in the future. It has been shown by the American Academy of Pediatrics (2003) that excessively controlling parental behaviour, including maternal restraint, verbal prompting to eat at mealtime, attentiveness to non-eating behaviors and perception of daughter's risk of being overweight, can have detrimental effects on children's ability to self-regulate energy intake,. Parents should intervene with their child in non0judgmental, blame-free manner so that unintended negative impact on the child's self concept is avoided (Passehl et al., 2004).

Recognizing childhood obesity is one thing, but knowing what to do is the major challenge. There is very little medical experience in treating the condition and the medial evidence in treating obese children is not encouraging. There has been evidence that a person would undergo repeated dieting finds it harder to lose weight with each diet session. Dieting among children is very risky as childhood is a period of growth and any lack of nutrients could be potentially harmful (Bunce & Hunt, 1987). The Oxford County Board of Health (2002) has suggested that parents of children that are already obese or overweight should aim for their child to grow into their current weight, not to lose weight and give your child the same foods as the rest of the family, do not single them out with different foods and never tell a children that they are "on a diet" or "too fat." It is very important to keep in mind that children are growing and their nutritional requirements are quite high compared with adults. Putting kids on a "diet" can lead to growth and development delays (Fledman & Beagan, 1994), as well as being psychologically harmful. The most important part of an action plan is to focus on a more active lifestyle for children.

A study conducted by James et al. (2004) determined that if a school-based educational program aimed at reducing consumption of carbonated drink can prevent excessive weight gain in children. The study was conducted at six primary schools in southwest England and there was a focus on educational programs on nutrition throughout one school year. The results included a decrease in the consumption of carbonated drinks by 0.6 glasses in the intervention group, but increased by 0.2 glasses in the control group. At 12 months the percentage of overweight and obese children increased in the control group by 7.5% compared with a decrease in the intervention group by 0.2%. The study concluded that a targeted school-based educational program produced a modest reduction in the number of carbonated drinks consumed, which was associated with a reduction in the number of overweight and obese children (James et al., 2004). There have been many multivariable intervention programs that have shown minimal effects on the rates of obesity, the above study mentioned focused on only a single variable: the consumption of carbonated beverages and its effect on obesity. This study provides hope that single-variable intervention maybe successful in limiting obesity and it also draws our attention to the significant contribution of soda consumption on obesity. Children, parents and schools have been overwhelmed with messages regarding diet, nutrition, exercise. The above study gives children, parents and school a specific goal, to decrease soda consumption with the benefit of weight reduction.

Helping overweight or obese children loose weight has been shown to be effective when there is a team (pediatrician, dietician and other healthcare professionals) approach. Dr. Nieman (2004) also suggests that there are many possible areas of change for overweight and obese children, they can switch from full fat dressings to reduced fat or fat-free varieties and there can be a decrease in the number of food items that are offered as rewards. Becoming active is a key factor for weight reduction, but may not be very easy. Taking into account how children think and behave is important when designing physical activity programs.


The causes of obesity, numerous recommendations and initiatives have been discussed that could potentially be effective for decreasing the rates of childhood obesity. The preventative recommendations seem to be simple enough to implement, but it is a matter or getting everyone to work together. In today's society, too many parents are busy with their jobs and focusing on supporting the family that they often forget their children. There has also been an increase in the number of single parent families and in these situations, there are strong effects on the children's health and diet. Therefore society, especially parents, health professional, teachers and other school officials need to work together to combat this "epidemic."

There is clearly a need for health promotion policies in schools concerning diet and exercise, support from food industries to offer more nutritious food, support from both public and private industries to facilitate healthy pregnancies and local and provincial and national funding and legislation to increase access to playground and recreational facilities. The long-term benefits of reducing the obesity rates among children are many and include the prevention of obese children from entering adulthood with a long list of diseases. Leadership and advocacy from both health professionals and scientists is required to bring about these changes and bring the childhood obesity "epidemic" to an end.


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