Talk:Fundamentals of Human Nutrition/Overweight and obesity

Introduction
Children need a healthy, balanced diet that gives them enough energy to grow and develop. This means that children usually need to take in more energy than they use and this extra energy forms new tissues as they grow. However, if children regularly take in too much energy, this is stored as fat and they will put on excess weight. 1

Childhood obesity is one of the most serious public health challenges of the 21st century. The problem is global and is steadily affecting many low- and middle-income countries, particularly in urban settings. The prevalence has increased at an alarming rate. Globally, in 2010 the number of overweight children under the age of five, is estimated to be over 42 million. Close to 35 million of these are living in developing countries.2

Many factors, including genetics, environment, metabolism, lifestyle, and eating habits, are believed to play a role in the development of obesity. However, more than 90% of cases are idiopathic; less than 10% are associated with hormonal or genetic causes.3

Overweight and Obesity
Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health.2 Operational definitions of obesity in adults are derived from statistical data that analyze the association between body mass and the risk of acute and long-term morbidity and mortality. Because acute medical complications of obesity are less common in children and adolescents than in adults, and because longitudinal data on the relation between childhood weight and adult morbidity and mortality are more difficult to interpret, no single definition of obesity in childhood and adolescence has gained universal approval.

Some investigators have used the terms overweight, obese, and morbidly obese to refer to children and adolescents whose weights exceed those expected for heights by 20%, 50%, and 80-100%, respectively. The body mass index (BMI) has not been consistently used or validated in children younger than 2 years. Because weight varies in a continuous rather than a stepwise fashion, the use of these arbitrary criteria is problematic and may be misleading. 3

A few extra pounds does not suggest obesity. However they may indicate a tendency to gain weight easily and a need for changes in diet and/or exercise. Generally, a child is not considered obese until the weight is at least 10 percent higher than what is recommended for their height and body type. Obesity most commonly begins between the ages of 5 and 6, or during adolescence. Studies have shown that a child who is obese between the ages of 10 and 13 has an 80 percent chance of becoming an obese adult. 4

Measuring overweight and obesity
It is difficult to develop one simple index for the measurement of overweight and obesity in children and adolescents because their bodies undergo a number of physiological changes as they grow. Depending on the age, different methods to measure a body's healthy weight are available.2

Using Body Mass Index (BMI) to Estimate Overweight and Obesity
The BMI is the tool most commonly used to estimate overweight and obesity in children and adults. The BMI is a continuous, although imperfect, measure of body fatness. Calculated as weight (kg) divided by height (m2).The BMI is used because, for most people, it correlates with the amount of fat in their bodies. Children grow at different rates at different times, so it is not always easy to tell if a child is overweight. The BMI correlates closely with total body fat (TBF), which is estimated using dual-energy x-ray absorptiometry (DEXA) scanning in children who are overweight and obese. Normal values for BMI vary with age, sex, and pubertal status, and standard curves representing the 5th through the 95th percentiles for BMI in childhood and adolescence were generated using data from the 1988-1994 NHANES. 35

BMI of Children and Adolescents Ages 2–19

BMI	Classification At or above the 85th percentile	Overweight or obese At or above the 95th percentile	Obese

Special charts, called BMI centile charts, have been developed to show whether children are under or overweight for their age. These charts compare a child’s BMI against other children of the same sex and age. Tool E4 -This tool contains detailed information on the measurement and assessment of overweight and obesity in children. It provides information on how to measure overweight and obesity using Body Mass Index (BMI) and growth reference charts; provides information on measuring waist circumference; and provides details on how to assess overweight and obesity in children. BMI charts are provided at the end of this tool for girls and boys. This tool is consistent with NICE guidance and also Department of Health recommendations. It is for all healthcare professionals measuring and assessing overweight and obese children.6

Causes for Obesity
The causes of obesity are complex and include genetic, biological, behavioral and cultural factors. Obesity occurs when a person eats more calories than the body burns up. If one parent is obese, there is a 50 percent chance that their children will also be obese. However, when both parents are obese, their children have an 80 percent chance of being obese. Although certain medical disorders can cause obesity, less than 1 percent of all obesity is caused by physical problems. Obesity in childhood and adolescence can be related to:
 * poor eating habits
 * overeating
 * lack of exercise (i.e., couch potato kids)
 * family history of obesity
 * medical illnesses (endocrine, neurological problems)
 * medications (steroids, some psychiatric medications)
 * stressful life events or changes (separations, divorce, moves, deaths and abuse)
 * family and peer problems
 * low self-esteem
 * depression or other emotional problems 4

WHO recognizes that the increasing prevalence of childhood obesity results from changes in society. Childhood obesity is mainly associated with unhealthy eating and low levels of physical activity, but the problem is linked not only to children's behaviour but also, increasingly, to social and economic development and policies in the areas of agriculture, transport, urban planning, the environment, food processing, distribution and marketing, as well as education.

The problem is societal and therefore it demands a population-based multisectoral, multi-disciplinary, and culturally relevant approach.

Unlike most adults, children and adolescents cannot choose the environment in which they live or the food they eat. They also have a limited ability to understand the long-term consequences of their behaviour. They therefore require special attention when fighting the obesity epidemic. 2

Health risks now
Childhood obesity can have a harmful effect on the body in a variety of ways. Obese children are more likely to have–
 * High blood pressure and high cholesterol, which are risk factors for cardiovascular disease (CVD). In one study, 70% of obese children had at least one CVD risk factor, and 39% had two or more.
 * Increased risk of impaired glucose tolerance, insulin resistance and type 2 diabetes.
 * Breathing problems, such as sleep apnea, and asthma.
 * Joint problems and musculoskeletal discomfort.
 * Fatty liver disease, gallstones, and gastro-esophageal reflux (i.e., heartburn).
 * Obese children and adolescents have a greater risk of social and psychological problems, such as discrimination and poor self-esteem, which can continue into adulthood.

Health risks later

 * Obese children are more likely to become obese adults. Adult obesity is associated with a number of serious health conditions including heart disease, diabetes, and some cancers.
 * If children are overweight, obesity in adulthood is likely to be more severe. 7

Prevention of obesity in children
Overweight and obesity, as well as related noncommunicable diseases, are largely preventable. It is recognized that prevention is the most feasible option for curbing the childhood obesity epidemic since current treatment practices are largely aimed at bringing the problem under control rather than effecting a cure. The goal in fighting the childhood obesity epidemic is to achieve an energy balance which can be maintained throughout the individual's life-span.

General recommendations

 * increase consumption of fruit and vegetables, as well as legumes, whole grains and nuts;
 * limit energy intake from total fats and shift fat consumption away from saturated fats to unsaturated fats;
 * limit the intake of sugars; and
 * be physically active - accumulate at least 60 minutes of regular, moderate- to vigorous-intensity activity each day that is developmentally appropriate.

Societal Recommendations
Curbing the childhood obesity epidemic requires sustained political commitment and the collaboration of many public and private stakeholders.

Governments, International Partners, Civil Society, NGO's and the Private Sector have vital roles to play in shaping healthy environments and making healthier diet options for children and adolescents affordable, and easily accessible. It is therefore WHO's objective to mobilize these partners and engage them in implementing the Global Strategy on Diet, Physical Activity and Health.

WHO supports the designation, the implementation, the monitoring and the leadership of actions. A multisectoral approach is essential for sustained progress: it mobilizes the combined energy, resources and expertise of all global stakeholders involved. 2

Population-based approaches to childhood obesity prevention - The document published by WHO, aims to provide Member States with an overview of the types of childhood obesity prevention interventions that can be undertaken at national, sub-national and local levels. The document first outlines guiding principles for the development of a population-based childhood obesity prevention strategy and then describes the approaches for population-based obesity prevention. There is a broad range of population-level actions that governments can take to prevent childhood obesity. A comprehensive childhood obesity prevention strategy will incorporate aspects of each of the key components. 8


 * 1) http://www.bupa.co.uk/individuals/health-information/directory/o/child-obesity
 * 2) http://www.who.int/dietphysicalactivity/childhood/en/
 * 3) http://emedicine.medscape.com/article/985333-overview
 * 4) http://www.aacap.org/cs/root/facts_for_families/obesity_in_children_and_teens
 * 5) http://win.niddk.nih.gov/statistics/index.htm
 * 6) http://www.fph.org.uk/uploads/HealthyWeight_SectE_Toolkit04.pdf
 * 7) http://www.cdc.gov/obesity/childhood/basics.html
 * 8) http://www.who.int/dietphysicalactivity/childhood/approaches/en/