Energy intake is the calories ingested in the form of food and beverages. Children require a dietary pattern consisting of a variety of foods that provide all the necessary nutrients to support normal growth and development, as well as regular physical activity. Thus, a balanced diet refers to the consumption of appropriate amounts of a wide variety of nutrient-dense foods that provide adequate amounts and proportions of macronutrients (protein, fat, and carbohydrates) as well as sufficient essential micronutrients (vitamins, minerals) and dietary fiber, in addition to providing adequate energy to meet the needs of maintenance, growth, and development.

Although “energy intake = energy expenditure” looks like a fairly basic equation, in reality it is extraordinarily complex when considering the multitude of genetic, biological, psychological, sociocultural, and environmental factors that affect both sides of the energy balance equation and the interrelationships among these factors (Figure 3-2). For example, the amount, type, and intensity of physical activity influence body composition and physical fitness, which in turn influence the energy cost of physical activity (Hill et al., 2004).

There are several concepts regarding energy balance and weight gain in children and youth that the committee determined were important to clarify:

  • Genetics is a factor in excess weight but it is not the explanation for the recent epidemic of obesity (Koplan and Dietz, 1999). Although inherited tendencies toward weight gain may be a partial explanation for excess weight in children, as discussed below, there have been no measurable changes in the genetic composition of the population during the recent decades that could explain the significant increases in obesity.

  • Growth spurts do occur at several points throughout childhood and adolescence, but it cannot be assumed that a child will lose his or her excess weight at those times. Many experienced clinicians assess an individual child’s relative weight status by examining the consistency of that child’s weight or BMI percentiles over time. Thus, for example, after the age of about 4 years, normally growing children who are in the 20th or 50th or 65th percentile for weight would be expected to remain around these same percentiles for weight, during the remainder of their childhood. However, what can be considered normal variation to that pattern is not yet known, and is an important research question.

  • Physiological reasons for a child’s excess weight should be carefully explored by health-care professionals. However, the identifiable medical conditions that cause childhood obesity are rare and are not the principal underlying causes of the current obesity epidemic in the population.

  • The perceptions of what healthy children should “look like” differ among generations, cultures, and individuals. However, it is important that obesity not become the norm in society for children and youth as it poses

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