The 1 to 10 year old child.
Most children, given access to a varied diet from all the food groups (but not including excessively, artificially attractive items, like candies), will choose adequate amounts of all nutrients.
Erratic eating patterns tend to even out over time, and cause more harm to parents (anxiety) than to the children.
Dieting for children: is childhood obesity a problem? (see Whitaker RC, Wright JA, Pepe MS, Seidel KD, Dietz WH. Predicting obesity in young adulthood from childhood and parental obesity. N Engl J Med 1997 Sep 25;337(13):869-873.)