http://www.medpagetoday.com/Pediatrics/Obesity/dh/6395
Low-Calorie Snacks May Not Help the Young Keep Pounds Off
August 10, 2007  EDMONTON, Alberta

Diet food may train young rats-and children-to overeat by confusing
calorie-content cues, researchers said. That leads to overeating at meals,
said W. David Pierce, And, they theorized, their findings likely translate
to children.As a result of early experience, children learn about tastes and
other gustatory cues that signal the caloric contents of foods and
beverages.

Explain to interested patients that the study may help explain why diet soda
has been more strongly linked to obesity than regular soda. Inform patients
that the study included only juvenile rats, but may have implications for
children if the findings are confirmed in further studies in humans.
Low-calorie food and drink are usually assumed to help in the obesity
battle, but an animal study reported in the August issue of the journal
Obesity shows that low-calorie snacks can distort the way the young learn to
correlate flavor with calorie content.

Primary Source :

Pierce WD, et al "Overeating by Young Obesity-prone and Lean Rats Caused by
Tastes Associated With Low Energy Foods" Obesity 2007;15:1969-1979.

So another one Will , this time with a hint of an explanation
Gys