出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/08/01 19:15:52」(JST)
| Childhood obesity | |
|---|---|
| Classification and external resources | |
Children with varying degrees of body fat.
|
|
| ICD-10 | E66 |
| ICD-9 | 278 |
| DiseasesDB | 9099 |
| MedlinePlus | 003101 |
| eMedicine | med/1653 |
| MeSH | C23.888.144.699.500 |
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.[1] The term overweight rather than obese is often used in children as it is less stigmatizing.[2] In order to prevent or reverse obesity in children it is necessary to perform a population wide reassessment of the calorie intake as well as activity recommendation due to the sedimentary lifestyle of children nowadays.[3]
|
BMI for age percentiles for boys 2 to 20 years of age.
|
BMI for age percentiles for girls 2 to 20 years of age.
|
Body mass index (BMI) is acceptable for determining obesity for children two years of age and older.[4] The normal range for BMI in children vary with age and sex. The Centers for Disease Control and Prevention defines obesity as a BMI greater than or equal to the 95th percentile. It has published tables for determining this in children.[5]
The first problems to occur in obese children are usually emotional or psychological.[6] Childhood obesity however can also lead to life-threatening conditions including diabetes, high blood pressure, heart disease, sleep problems, cancer, and other disorders.[7][8] 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.[9] Asthma severity is not affected by obesity however.[10] Overweight children are more likely to grow up to be overweight adults.[8] Obesity during adolescence has been found to increase mortality rates during adulthood.[11]
Obese children often suffer from teasing by their peers.[12][13] Some are harassed or discriminated against by their own family.[13] Stereotypes abound and may lead to low self-esteem and depression.[14]
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.[15]
| System | Condition | System | Condition |
|---|---|---|---|
| Endocrine |
|
Cardiovascular |
|
| Gastroentestinal |
|
Respiratory |
|
| Musculoskeletal |
|
Neurological |
|
| Psychosocial |
|
Skin |
|
[18]
Children who are obese are likely to be obese as adults. Thus, they are more at risk for adult health problems such as heart disease, type 2 diabetes, stroke, several types of cancer, and osteoarthritis. One study showed that children who became obese as early as age 2 were more likely to be obese as adults.[19] According to an article in the New York Times all of these health effects are contributing to a shorter lifespan of five years for these obese children. It is the first time in two centuries that the current generation of children in America may have a shorter life span than their parents.[20]
Childhood obesity can be brought on by a range of factors which often act in combination.[21][22][23][24][25] “Obesogenic environment” is the medical term set aside for this mixture of elements.[26] The greatest risk factor for child obesity is the obesity of both parents. This may be reflected by the family's environment and genetics.[27] Other reasons may also be due to psychological factors and the child's body type.
A 2010 review stated that childhood obesity likely is the result of the interaction of natural selection favouring those with more parsimonious energy metabolism and today's consumerist society with easy access to energy dense cheap foods and less energy requirements in daily life.[28]
"Obesity of mothers predisposes their offsprings to obesity by epigenetic, prenatal effects." Prevention and awareness programs should target children as early as kindergarten with the involvement of parents. The approaches include changing the environment children are in. For example, the banning of pop being sold at vending machines in school.[29]
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 that even though the children believed they were eating less their actual 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%.[30] A second study of 5,106 children showed similar results. Even though the children ate an improved diet there was no effect found on BMI.[31] 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 while it is felt that they must occur in the home, the community, and the school simultaneously to have a significant effect.[32]
Calorie-rich drinks and foods are readily available to children. Consumption of sugar-laden soft drinks may contribute to childhood obesity. In a study of 548 children over a 19 month period the likelihood of obesity increased 1.6 times for every additional soft drink consumed per day.[33]
Calorie-dense, prepared snacks are available in many locations frequented by children. As childhood obesity has become more prevalent, snack vending machines in school settings have been reduced by law in a small number of localities. Some research suggests that the increase in availability of junk foods in schools can account for about one-fifth of the increase in average BMI among adolescents over the last decade.[34] Eating at fast food restaurants is very common among young people with 75% of 7th to 12th grade students consuming fast food in a given week.[35] The fast food industry is also at fault for the rise in childhood obesity. This industry spends about $4.2 billion on advertisements aimed at young children. McDonald's alone has thirteen websites that are viewed by 365,000 children and 294,000 teenagers each month. In addition, fast food restaurants give out toys in children's meals, which helps to entice children to buy the fast food. Forty percent of children ask their parents to take them to fast food restaurants on a daily basis. To make matters worse, out of 3000 combinations created from popular items on children's menus at fast food restaurants, only 13 meet the recommended nutritional guidelines for young children.[36] Some literature has found a relationship between fast food consumption and obesity.[37] Including a study which found that fast food restaurants near schools increases the risk of obesity among the student population.[38]
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.[39]
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.[40] 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.[41]
Many children fail to exercise because they are spending time doing immobile activities such as computer usage, playing video games or watching television. Technology has a large factor on the children's activeness. 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.[41] A randomized trial showed that reducing TV viewing and computer use can decrease age-adjusted BMI; reduced calorie intake was thought to be the greatest contributor to the BMI decrease.[42]
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.[43]
Childhood inactivity is linked to obesity in the United States with more children being overweight at younger ages. In a 2009 preschool study 89% of a preschoolers' day was found to be sedentary while the same study also found that even when outside, 56 percent of activities were still sedentary. One factor believed to contribute to the lack of activity found was little teacher motivation,[44] but when toys, such as balls were made available, the children were more likely to play.[44]
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.
In 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.[45] 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.[1][32] The percentage of obesity that can be attributed to genetics varies from 6% to 85% depending on the population examined.[46]
Children's 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 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.[47] The results of a survey in the UK published in 2010 imply that children raised by their grandparents are more likely to be obese as adults than those raised by their parents.[48] An American study released in 2011 found the more mothers work the more children are more likely to be overweight or obese.[49]
Various developmental factors may affect 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.[50] 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).[51]
A child's weight may be influenced when he/she is only an infant. A nationally representative sample of US preschoolers found that infants whose early weight status was normal tended to retain a normal weight status and not to develop an unfavorable status (at-risk, obese). In contrast, children who were obese at an early age were more likely to have an at-risk or obese weight category at a later age.[52] Researchers also 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.[53]
Cushing's syndrome (a condition in which the body contains excess amounts of cortisol) may also influence childhood obesity. 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.[54]
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.[55]
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 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.[56] 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.[57] 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.[58] 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.[59]
The escalation of obese children is due to the upsurge of technology, increase in snacks and portion size of meals, and the decrease in the physical activity of children. If children were more mobile and less sedentary, the rate of obesity would decrease. Children have to put down the electronic devices and spend more time outside playing or exploring other options of physical acitvity. A study found kids that use electronic devices 3 or more hours a day had between a 17- 44% increased risk of being overweight, or a 10- 61% increased risk of obese (Cespedes 2011).[full citation needed] Parents have to recognize the signs and encourage their children to be more physically active. There are many programs designed to encourage activities such as Letsmove.gov, a program launched by the first lady, Michelle Obama to help combat problems with this epidemic of obesity.
Exclusive breast-feeding is recommended in all newborn infants for its nutritional and other beneficial effects.[50] Parents could change the diet and lifestyle of their offspring by offering appropriate food portions, increasing physical activity, and keeping sedentary behaviors at a minimum. This may also decrease the obesity levels in children.[60]
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.[50] 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.[61]
Rates of childhood obesity have increased greatly between 1980 and 2010.[60] Currently 10% of children worldwide are either overweight or obese.[2]
The rate of overweight and obesity among Canadian children has increased dramatically in recent years. In boys, the rate increased from 11% in 1980s to 30% in 1990s.[62]
The rate of overweight and obesity in Brazilian children increased from 4% in the 1980s to 14% in the 1990s.[62] In 2007 the prevalence of children overweight and childhood obesity was 11.1% and 2.7% in girls, 8.2% and 1.5% in boys, respectively.[63]
The rate of obesity among children and adolescents in the United States has nearly tripled between the early 1980s and 2000. It has however not changed significantly between 2000 and 2006 with the most recent statistics showing a level just over 17 percent.[64] In 2008, the rate of overweight and obese children in the United States was 32%, and had stopped climbing.[65] In 2011, a national cohort study of infants and toddlers found that nearly one-third of US children were overweight or obese at 9 months and 2 years old.[66] Infant weight status was strongly associated with preschool weight status.[52]
Since the onset of the 21st Century, Australia has found that childhood obesity has followed trend with the United States. Information garnered has concluded that the increase has occurred in the lower socioeconomic areas where poor nutritional education has been blamed.
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.[67]
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.[68]
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%.[69]
Obese children and adolescents are more likely to become obese as adults. For example, one study found that approximately 80% of children who were overweight at aged 10–15 years were obese adults at age 25 years. Another study found that 25% of obese adults were overweight as children. The latter study also found that if overweight begins before 8 years of age, obesity in adulthood is likely to be more severe.[70]
A study has also found that tackling childhood obesity will not necessarily lead to eating disorders later in life.[71]
A review of secular trends in the number of overweight or obese children have come to the conclusion that prevalence had increased during the past two decades in the most industrialised countries, apart from Russia and Poland, and in several low-income countries, especially in urban areas. Prevalence doubled or tripled between the early 1970s and late 1990s in Australia, Brazil, Canada, Chile, Finland, France, Germany, Greece, Japan, the UK, and the USA. By 2010, more than 40% of children in the North American and eastern Mediterranean WHO regions, 38% in Europe, 27% in the western Pacific, and 22% in southeast Asia were predicted to be overweight or obese. However, that 2006 review pre-dates recent data, which, although still too soon to be certain, suggest that the increase in childhood obesity in the USA, the UK, and Sweden might be abating.3–5 [72]
|accessdate= requires |url= (help)
|
||||||||||||||||||||||||||||||||||||||
全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.
| リンク元 | 「小児肥満症」 |
| 関連記事 | 「childhood」「obesity」 |