This article linked through Weight Matters demonstrates the basic misunderstanding of child obesity.
Remove all processed foods is necessary for recovery but not sufficient. You also need to remove the cause of overeating. If the child suffers from anxiety, stress, isolation, boredom, abuse, neglect, oppressive over control, insecurity, etc, those problems must be dealt with in some manner. The driving force must be removed or the child must be taught to deal with the driver. If the parent does not do this, someone else may, and that may show the ignorance or arrogance of the parent. If the parent is the driving force, and the child recognizes this, there will be a strained or absent adult to adult relationship.
It is easy to point to the child, and think mental illness, maladjustment, or the like. But is it the child or there environment? The child may just be using food as a mild sedative. High blood glucose/high insulin is a mild sedative. Perhaps the child need to learn stoic philosophy as a means of dealing with his/her environment.
And a picture just because