Chinese swimming phenomenon Ye Shiwen has "woken from a nightmare" after a growth spurt and sleepless nights due to worry prompted a dramatic loss of form, a report said.

Ye, 17, who won two individual medley gold medals at the London Olympics, told Xinhua news agency she was now back on track after a "terrible" world championships this year.

Olympic champion Ye finished fourth in the 200m individual medley at Barcelona and seventh in the 400m race -- more than 10 seconds slower than her world record set in London.

"My form is not as good as 2012. Maybe one of the reasons is that I put on some weight and got heavier in the water," she told Xinhua. "I am right in the middle of body development and almost five kilogrammes (10 pounds) heavier than I was in 2012."

Ye added: "I was heavier and not in good shape in Barcelona. On the other hand, I was too eager to show my best while I was not in peak form. The stress made me sleepless before and during the world championships, and the results were terrible."

Ye was put under considerable scrutiny at the Olympics when she swam the final leg of the 400m individual medley quicker than men's winner Ryan Lochte, attracting doping innuendo.

She said she was now looking forward to next year's Asian Games in South Korea, after she starred at the multi-sport tournament's last edition on home soil.

"Barcelona is the past, and I want to look on the bright side of it. It is a valuable lesson," she said during the East Asian Games in Tianjin.