When Izzie returns from the school trip to Italy, she attempts to put on her black jeans, but they won't do up! It looks as though she has put on three pounds from the trip and since she put on another five pounds at Christmas all her clothes have become incredibly tight. Izzie then goes into the horrible spiral of becoming obsessive about her weight - worrying, weighing herself all the time, trying diets, and actually gaining more weight. She begins to lose her confidence and all the good things that happen to her - being selected for a TV teen panel, catching the eye of an older boy - fade because of this. The girls all rally round to help her, but will Izzie see the light?