Childhood obesity rates are concerning because the future health implications of being overweight for so long are not known. Understandably, researchers have been interested in understanding the causes of childhood obesity. The traditional view that weight gain is caused by overeating or lack of physical exercise creating a positive energy balance has been largely superseded. In fact, recent studies show that childhood obesity is much more complex than was once considered and may involve multiple factors, many of which are subtle and difficult to detect. Recently attention has turned to the composition of meals and the overall quality of the nutrition contained within. Manipulating the composition of the meal to increase the overall quality has been shown to be an effective strategy. Reducing low quality foods such as refined carbohydrates and sugars with high quality alternatives such as fruits and vegetables has been largely successful.
For example, researchers1 have investigated the effect of the portion size of a low quality main course on the energy intake of ad libitum feeding of high quality side dishes, in 17 children age 3 to 6 years. The main meal consisted of macaroni cheese (100, 160, 220, 280, 340 and 400g) and the accompanying food consisted of green beans with whipped butter, unsweetened applesauce, a whole wheat roll and a fixed serving of milk or soy milk (providing a total of 373 kcal). Increasing portion size of the low quality main meal decreased the portion size of the high quality foods. Therefore, as the energy density of the portion size increased, the energy density of the lunch increased. The authors also reported that children with the highest body mass index (BMI) increased their total energy intakes the most with increasing main course size.
Therefore serving smaller portions of low quality main courses could decrease the total energy density of the meal by a concomitant increase the amount of high quality side dishes consumed. This may be an effective strategy to increase fruit and vegetable intakes and thus increase the overall quality of the diet. However, the most interesting finding in this study was perhaps that those children with the highest BMI tended to respond to larger main course portions with a greater increase in total energy intake. Therefore, given the opportunity, those children with the highest BMI ate the most food. This suggests that the regulatory mechanisms of the normal weight children were preventing overeating as recorded by their smaller ad libitum intakes. This regulatory restraint was lacking from the children with the highest BMI suggesting that metabolic abnormality might be a contributory factor in weight gain.
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