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Med J Aust 2000; 173 Suppl 7 August: S13-S14

The nutritional status and level of physical activity of Australian children is an important public health issue. Although most Australian children have access to an adequate food supply and the opportunity to be physically active, there are concerns about the balance and adequacy of their dietary intake and physical activity levels. The 1995 National Nutrition Survey (NNS) provides a comprehensive picture of the eating habits and foods and nutrients consumed by a representative population sample of Australian children (1221 children aged 2-11 years). Overall, the nutrients consumed increased with age, with boys generally consuming more than girls. Although fat intake, at 33% of energy consumption,² approximates that suggested by the NHMRC dietary guidelines for this age group (35% of energy),⁴ the saturated fat intake was higher than recommended. The results of the NNS show that calcium intake needs to be higher to meet the needs of skeletal growth. Iron intake in girls also needs to be increased. The intake of fruit and vegetables was lower than recommended, with 30% of 2-7-year-olds consuming no fruit, and a similar percentage consuming no vegetables, on the day of the survey. Although over 98% of children ate cereal foods on the day of the survey, 4-7-year-old girls and 8-11-year-old boys were not eating enough, especially from the "nutritious cereal" group, including breakfast cereals, bread, pasta, rice and nutritious grain-based snacks.

To meet nutrient requirements, children need regular meals and snacks. Snacks provide a half to a third of the energy intake for most children. Snacking has been shown to improve attention, recall, even arithmetic problem solving, in some studies. Athletic children have high energy and carbohydrate requirements. Meeting these needs is also important for enhancing sports performance. Effective rehydration is also a key strategy for safe and optimal performance. Children rarely drink enough to replenish fluid losses and need to learn to consume more than thirst dictates. While water is often described as the best choice of fluid, there are situations when sports drinks are advantageous.

Research suggests that 20%-25% of Australian children are either overweight or obese, with a similar number being physically inactive. Children who are sufficiently active, particularly those who participate in vigorous-intensity sports at least 3-4 times per week, enjoy a lower risk of developing "lifestyle diseases" later in life, and are also laying the foundations of a healthy adult lifestyle. Prior to puberty, a variety of activities or sports should be encouraged. Children need a safe environment in which to be active, and the opportunity to develop the skills fundamental to rewarding participation in physical activity. Parents who model desired behaviour by being active themselves and by encouraging and supporting their children's physical activity can have a powerful influence. Unfortunately, the modern environment promotes sedentariness in countless ways (eg, excessive TV viewing and computer game use, use of cars rather than walking).

Serial growth measures are an excellent way to monitor growth and nutritional status during childhood. However, measuring height and weight to determine body mass index (weight/height²) is the most convenient way to assess degree of fatness. Currently, this measure is compared on a BMI-for-age chart based on US data; current research on an international chart has just been published. Serial growth measurements are particularly useful for monitoring the development of overweight or obesity. Measurements of waist circumference or waist-to-hip ratio may be helpful for identifying children with a more central fat distribution, which can indicate an increased risk of cardiovascular disease.

All major cardiovascular risk factors can begin in childhood. In addition to central obesity, cardiovascular risk in children is increased by high cholesterol levels, active or passive smoking, diabetes, high blood pressure and genetic predisposition (positive family history). Research provides a strong justification for reducing risk factors in young persons. Children may develop fatty streaks in their aortas from as young as four years of age, and even in the coronary vessels before they are 10. Early screening for risk factors is recommended in children from high risk families with established early atherosclerosis in close family members.

Osteoporosis is also a major public health problem owing to the morbidity and mortality associated with fractures. Although these fractures occur late in life, the pathogenesis of osteoporosis may begin in childhood. Low peak bone mineral density in adulthood may be a more important determinant of osteoporosis than age-related bone mass. Thus, it is important that children of all ages and stage of maturation participate regularly in weight-bearing exercise and consume adequate calcium.

Successful weight management requires reduction in overall energy intake, with particular emphasis on fat reduction, and an increase in physical activity. Early intervention is important in children, as the state of being overweight is unlikely to remit spontaneously. Managing childhood obesity involves long term change. In overweight children, the overall goal is to maintain weight while they grow in height. Parents are the prime agents of change, and need to set limits, to observe, and to model and praise positive behaviours. Drugs, very low energy diets and surgery generally have no place in the management of childhood obesity.

Children in First World countries are rapidly socialised into a rejection of obesity. Fat body shapes are more likely to be branded as lazy, less intelligent, socially isolated and unhealthy, and overweight children tend to have low body-esteem. Anecdotal reports of peer teasing about being overweight are starting to stimulate research. Evidence is accumulating that self-report of dieting among children is linked with weight concerns and dieting in the family, and that this process can start before the age of five.

The following recommendations developed from this article are provided to guide medical and allied health professionals working with primary school age children.

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