Childhood obesity

  Childhood obesity is a medical condition that affects children. It is characterized by a weight well above the mean for their height and age and a body mass index well above the norm. Childhood obesity is considered by many to be an "epidemic" in Western countries, in particular, the United States, United Kingdom and Australia. Over 15% of American children are currently considered obese, and the number is growing ^[1].

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Causes

  As with many conditions, childhood obesity can be brought on by a range of factors, often in combination.^{[2][3][4][5][6]}

Eating Habits

Childhood obesity results from poor eating habits. In a study of 99 children, between 11 and 16 years, professional dieticians put the children on a regulated diet program for a nine month period, leading to an average weight loss of 66 pounds. However, during the two year follow-up, dieticians discovered that intake of daily calories had increased by 391 calories, leading to weight gain in the subjects.^[7] Soft drink consumption may also be an unhealthy eating/drinking habit leading to childhood obesity. In a study of 548 children during a 19 month period, researchers examined the correlation of soft drink consumption to childhood obesity. They discovered children were 1.6 times more likely to be obese for every soft drink consumed each day.^[8] Daily consumption of fast food and junk food has dominated over healthy food choices. Researchers provided a lunchtime survey for a one year period to 1681 children, ages five to 12 years old. They discovered that although 68% of the children did have fruit in their lunchboxes, 90% of the children had junk food in their lunch boxes.^[9]In another study an FFFRU (Frequency of Fast Food Restaurant Use) survey was given to 4,746 students, in grades seven through 12, and researchers discovered that 75% of students had eaten at a fast food restaurant in the past week.^[10] Eating out on a regular basis has resulted in child weight gain. Researchers studied the dietary records of 101 healthy girls, from ages 8- 19 years over a one year period and a four to 10 year follow up. They discovered that girls who ate quick service food two or more times a week had a BMI z score(provides comparative measure of body fat accustomed for age) of .82, compared to those who ate it less than twice a week, with a BMI z score of .2- .28. ^[11]Childrens’ food choices are also influenced by family meals. Researchers provided a household eating questionnaire to 18,177 children, ranging in ages 11-21, 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/wk, those who at four to five family meals/wk 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/wk, compared to those who ate three or fewer family meals/wk, 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.^[12] Neglecting to eat certain meals completely can create weight gain. Children who fail to eat breakfast could face potential weight gain. Researchers provided a breakfast questionnaire to 14,000 children over a three year period and discovered that 7.35% more children who never ate breakfast were overweight, compared to overweight children who ate breakfast every day.^[13]

Physical Activity

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 nonobese 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. ^[14] 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 75-85% excess energy being stored as body fat and fat overfeeding produced 90-95% storage of excess energy as body fat.^[15] Many children fail to exercise because they are spending time doing stationary activities. 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/day, 4.5% more likely to be overweight when using a computer one or more hours/day, and unaffected by potential weight gain from playing video games.^[16]

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 11-12. 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.^[17]

Biological Factors

Children face many biological factors that may result in obesity. 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.^[18] Genetic causes also claim to be a cause of childhood obesity. Researchers studied 4997 children, ages 5-7, and 2631 parents over a five year period to examine the hereditary correlation n of obesity; parents were given a family nutrition questionnaire. Researchers discovered 50% of the children with obese mothers were obese or overweight and 40.1% of children with obese fathers were obese or overweight. However, 41.95% of children with normal weight mothers were obese or overweight and 34.25% of children with normal weight fathers were obese or overweight.^[19] Studies have also suggested that parental obesity may not be passed down to children. Researchers provided a parent questionnaire to the parents of 85 children, with the children being 36 months old. They discovered that girls were only .14 times likely to have similar BMI scores to parents and boys were only .48 times likely to have similar BMI scores to parents. This study demonstrates that there is no significant correlation between a parents’ influence on their obese child.^[20]

Developmental Factors and Illnesses

Children can have various developmental factors of the body that may result in obesity. A child’s body growth pattern may influence his/her 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 .67 had catch up growth (they were less likely to be overweight) compared to infants who had less than a .67 SD score (they were more likely to gain weight).^[21] 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.^[22]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 .077 points more on the caloric intake scale than did those without hypothyroidism.^[23]

Behavioral Factors

Childhood obesity may also be caused by various behavioral factors. Behavioral factors, such as boredom, sadness, and anxiety may influence a child’s health. Researchers surveyed 1,520 children, ages 9-10, 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 let 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. ^[24]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.^[25] This evidence may demonstrate a link between eating and stress.

Psychological Factors

Psychological factors also influence childhood obesity. Researchers did a health investigation of 496 girls, ages 11-15 with a four year follow up. They discovered four significant psychological factors to the girls’ obesity: dietary restraint, compensatory behaviors, depressive symptoms, and perceived parental obesity. The odd ratios (OR’s) these had with obesity were 3.16, 1.35, 2.32, and 3.97.^[26]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 nonobese adolescents who said they were depressed.^[27] 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.^[28]

Complications

Without a change in diet or exercise patterns, childhood obesity can lead to life-threatening conditions including diabetes, high blood pressure, heart disease, sleep problems, cancer, and other disorders.^[29][30] Studies have shown that overweight children are more likely to grow up to be overweight adults.^[31]

Obese children often suffer from teasing amongst their peers.^[32][33] Some are even harassed or discriminated against by their own family.^[34] Stereotypes abound and may lead to low self esteem and depression.^[35]

Studies

A study of 1800 children aged 2 to 12 in Colak, 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.^[36]

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.^[37] Although obesity is more common in girls,^[38] it is more apparent in boys who tend to accumulate fat in the stomach area, and, to a lesser extent, the back and chest.

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%. ^[39]

See also

• Hereditary factors in childhood obesity

References