Possible Clues:

• Childhood plumpness
• The young blubber?
• Adipose tissue disappearing in adolescence
• Successor to Lassie and Grease is lost on the youth as they grow up
• Dog's destiny to have tail docked? It'll make the young blubber
• Young boxer fine at losing this type of weight during adolescence
• Teen dieter's target, perhaps
• The sort of blubber you expect with an immature person
• The young blubber
• Problem of youth, or young boxer out of condition?