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Childhood obesity
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Childhood obesity is a condition where excess body fat negatively affects a child's health or wellbeing. As methods to determine body fat directly are difficult, the diagnosis of obesity is often based on BMI. Due to the rising prevalence of obesity in children and its many adverse health effects it is being recognized as a serious public health concern. The term overweight rather than obese is often used in children as it is less stigmatizing.
Classification
Body mass index (BMI) is acceptable for determining obesity for children two years of age and older.
Discussion
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Encyclopedia
Childhood obesity is a condition where excess body fat negatively affects a child's health or wellbeing. As methods to determine body fat directly are difficult, the diagnosis of obesity is often based on BMI. Due to the rising prevalence of obesity in children and its many adverse health effects it is being recognized as a serious public health concern. The term overweight rather than obese is often used in children as it is less stigmatizing.
Classification
Body mass index (BMI) is acceptable for determining obesity for children two years of age and older. The normal range for BMI in children vary with age and sex. The Center for Disease Control defines obesity as a BMI greater then the 95th percentile. It has published tables for determining this in children.
Effects on health
The first problems to occur in obese children are usually emotional or psychological. Childhood obesity however can also lead to life-threatening conditions including diabetes, high blood pressure, heart disease, sleep problems, cancer, and other disorders. Some of the other disorders would include liver disease, early puberty or menarche, eating disorders such as anorexia and bulimia, skin infections, and asthma and other respiratory problems. Studies have shown that overweight children are more likely to grow up to be overweight adults. Obesity during adolescence has been found to increases mortality rates during adulthood.
Obese children often suffer from teasing by their peers. Some are harassed or discriminated against by their own family. Stereotypes abound and may lead to low self esteem and depression.
A 2008 study has found that children who are obese have carotid arteries which have prematurely aged by as much as thirty years as well as abnormal levels of cholesterol.
Causes
As with many conditions, childhood obesity can be brought on by a range of factors which often act in combination.
Dietary
The effects of eating habits on childhood obesity are difficult to determine. A three year randomized controlled study of 1,704 3rd grade children which provided two healthy meals a day in combination with an exercise program and dietary counsellings failed to show a significant reduction in percentage body fat when compared to a control group. This was partly due to the fact the even though the children believed they were eating less their actually calorie consumption did not decrease with the intervention. At the same time observed energy expenditure remained similar between the groups. This occurred even though dietary fat intake decreased from 34% to 27%. A second study of 5,106 children showed similar results. Even though the children eat an improved diet there was not effect found on BMI. Why these studies did not bring about the desired effect of curbing childhood obesity has been attributed to the interventions not being sufficient enough. Changes were made primarily in the school environment well it is felt that they must occur in the home, the community, and the school simultaneously to have a significant effect.
Soft drink consumption may contribute to childhood obesity. In a study of 548 children over a 19 month period the likely of obesity increased by 1.6 for every increase in soft drink consumed per day.
Eating at fast food restaurants has become prevalent among young people with 75% of 7 to 12 grade students consuming fast food in a given week. Some literature has found a relationship between fat food consumption and obesity. Including a study which found that fast food restaurants near schools increases the risk of obesity among the student population.
Whole milk consumption verses 2% milk consumption in children of one to two years of age had no effect on weight, height, or body fat percentage. Therefore whole milk continues to be recommended for this age group. However the trend of substituting sweetened drink for milk has been found to lead to excess weight gain.
Sedentary lifestyle
Physical inactivity of children has also shown to be a serious cause, and children who fail to engage in regular physical activity are at greater risk of obesity. Researchers studied the physical activity of 133 children over a three week period using an accelerometer to measure each child's level of physical activity. They discovered the obese children were 35% less active on school days and 65% less active on weekends compared to non-obese children.
Physical inactivity as a child could result in physical inactivity as an adult. In a fitness survey of 6,000 adults, researchers discovered that 25% of those who were considered active at ages 14 to 19 were also active adults, compared to 2% of those who were inactive at ages 14 to 19, who were now said to be active adults. Staying physically inactive leaves unused energy in the body, most of which is stored as fat. Researchers studied 16 men over a 14 day period and fed them 50% more of their energy required every day through fats and carbohydrates. They discovered that carbohydrate overfeeding produced 7585% excess energy being stored as body fat and fat overfeeding produced 9095% storage of excess energy as body fat.
Many children fail to exercise because they are spending time doing stationary activities such as playing video games or watching TV. TV and other technology may be large factors of physically inactive children. Researchers provided a technology questionnaire to 4,561 children, ages 14, 16, and 18. They discovered children were 21.5% more likely to be overweight when watching 4+ hours of TV per day, 4.5% more likely to be overweight when using a computer one or more hours per day, and unaffected by potential weight gain from playing video games. A randomized trial showed that reducing television viewing and computer use can decrease age-adjusted BMI; reduced calorie intake was thought to be the greatest contributor to the BMI decrease.
Technological activities are not the only household influences of childhood obesity. Low-income households can affect a child's tendency to gain weight. Over a three week period researchers studied the relationship of socioeconomic status (SES) to body composition in 194 children, ages 1112. They measured weight, waist girth, stretch stature, skinfolds, physical activity, TV viewing, and SES; researchers discovered clear SES inclines to upper class children compared to the lower class children.
Genetics
Childhood obesity is often the result of an interplay between many genetic and environmental factors. Polymorphisms in various genes controlling appetite and metabolism predispose individuals to obesity when sufficient calories are present. As such obesity is a major feature of a number of rare genetic conditions that often present in childhood.
- Prader-Willi syndrome with a incidence between 1 in 12,000 and 1 in 15,000 live births is characterized by hyperphagia and food preoccupations which leads to rapid weight gain in those affected.
- Congenital leptin deficiency
In a children with early-onset severe obesity (defined by an onset before ten years of age and body mass index over three standard deviations above normal), 7% harbor a single locus mutation. One study found that 80% of the offspring of two obese parents were obese in contrast to less than 10% of the offspring of two parents who were of normal weight. The percentage of obesity that can be attributed to genetics varies from 6% to 85% depending on the population examined.
Home environment
Children's food choices are also influenced by family meals. Researchers provided a household eating questionnaire to 18,177 children, ranging in ages 1121, and discovered that four out of five parents let their children make their own food decisions. They also discovered that compared to adolescents who ate three or fewer meals per week, those who ate four to five family meals per week were 19% less likely to report poor consumption of vegetables, 22% less likely to report poor consumption of fruits, and 19% less likely to report poor consumption of dairy foods. Adolescents who ate six to seven family meals per week, compared to those who ate three or fewer family meals per week, were 38% less likely to report poor consumption of vegetables, 31% less likely to report poor consumption of fruits, and 27% less likely to report poor consumption of dairy foods.
Developmental factors
Various developmental factors may affects rates of obesity. Breast-feeding for example may protect against obesity in later life with the duration of breast-feeding inversely
associated with the risk of being overweight later on. A child's body growth pattern may influence the tendency to gain weight. Researchers measured the standard deviation (SD [weight and length]) scores in a cohort study of 848 babies. They found that infants who had an SD score above 0.67 had catch up growth (they were less likely to be overweight) compared to infants who had less than a 0.67 SD score (they were more likely to gain weight).
A child's weight may be influenced when he/she is only an infant. Researchers did a cohort study on 19,397 babies, from their birth until age seven and discovered that fat babies at four months were 1.38 times more likely to be overweight at seven years old compared to normal weight babies. Fat babies at the age of one were 1.17 times more likely to be overweight at age seven compared to normal weight babies.
Medical illness
Cushing's syndrome (condition in which body contains excess amounts of cortisol) may influence childhood obesity as well. Researchers analyzed two isoforms (proteins that have the same purpose as other proteins, but are programmed by different genes) in the cells of 16 adults undergoing abdominal surgery. They discovered that one type of isoform created oxo-reductase activity (the alteration of cortisone to cortisol) and this activity increased 127.5 pmol mg sup when the other type of isoform was treated with cortisol and insulin. The activity of the cortisol and insulin can possibly activate Cushing's syndrome.
Hypothyroidism is a hormonal cause of obesity, but it does not significantly affect obese people who have it more than obese people who do not have it. In a comparison of 108 obese patients with hypothyroidism to 131 obese patients without hypothyroidism, researchers discovered that those with hypothyroidism had only 0.077 points more on the caloric intake scale than did those without hypothyroidism.
Psychological factors
Researchers surveyed 1,520 children, ages 910, with a four year follow up and discovered a positive correlation between obesity and low self esteem in the four year follow up. They also discovered that decreased self esteem led to 19% of obese children feeling sad, 48% of them feeling bored, and 21% of them feeling nervous. In comparison, 8% of normal weight children felt sad, 42% of them felt bored, and 12% of them felt nervous. Stress can influence a child's eating habits. Researchers tested the stress inventory of 28 college females and discovered that those who were binge eating had a mean of 29.65 points on the perceived stress scale, compared to the control group who had a mean of 15.19 points. This evidence may demonstrate a link between eating and stress.
Feelings of depression can cause a child to overeat. Researchers provided an in-home interview to 9,374 adolescents, in grades seven through 12 and discovered that there was not a direct correlation with children eating in response to depression. Of all the obese adolescents, 8.2% had said to be depressed, compared to 8.9% of the non-obese adolescents who said they were depressed. Antidepressants, however, seem to have very little influence on childhood obesity. Researchers provided a depression questionnaire to 487 overweight/obese subjects and found that 7% of those with low depression symptoms were using antidepressants and had an average BMI score of 44.3, 27% of those with moderate depression symptoms were using antidepressants and had an average BMI score of 44.7, and 31% of those with major depression symptoms were using antidepressants and had an average BMI score of 44.2.
Management
Lifestyle
Exclusive breast-feeding is recommended in all newborn infants for its nutritional and other
beneficial effects. It may also protect against obesity in later life.
Medications
There are no medications currently approved for the treatment of obesity in children. Orlistat and sibutramine may however be helpful in managing moderate obesity in adolescence. Sibutramine is approved for adolescents older than 16. It works by altering the brain's chemistry and decreasing appetite. Orlistat is approved for adolescents older than 12. It works by preventing the absorption of fat in the intestines.
Epidemiology
10% of children worldwide are either overweight or obese.
Canada
Rates of obesity among Canadian children has increased dramatically in recent years. In boys rates increased from 11% in 1980s to over 30% in 1990s.
Brasil
Rates of obesity in Brazilian children increased from 4% in the 1980s to 14% in the 1990s.
United States
The rate of obesity among children and adolescents in the United States has nearly tripled between the early 1980s and 2000. It has however has not changed significantly between 2000 and 2006 with the most recent statistics showing a level just over 17 percent. In 2008, the rate of overweight and obese children in the United States was 32%, and had stopped climbing.
Studies
A study of 1800 children aged 2 to 12 in Colac, Australia tested a program of restricted diet (no carbonated drinks or sweets) and increased exercise. Interim results included a 68% increase in after school activity programs, 21% reduction in television viewing, and an average of 1 kg weight reduction compared to a control group.
A survey carried out by the American Obesity Association into parental attitudes towards their children's weight showed the majority of parents think that recess should not be reduced or replaced. Almost 30% said that they were concerned with their child's weight. 35% of parents thought that their child's school was not teaching them enough about childhood obesity, and over 5% thought that childhood obesity was the greatest risk to their child's long term health.
A Northwestern University study indicates that inadequate sleep has a negative impact on a child's performance in school, their emotional and social welfare, and increases their risk of being overweight. This study was the first nationally represented, longitudinal investigation of the correlation between sleep, Body Mass Index (BMI) and overweight status in children between the ages of 3 and 18. The study found that an extra hour of sleep lowered the children's risk of being overweight from 36% to 30%, while it lessened older children's risk from 34% to 30%.
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