Despite tens of kilometers walk and intense strength exercises everyday, Wang Zhen has to restrain himself to just half-full for each meal in his build-up to the 2014 IAAF Race Walking World Cup.

The men's 20km defending champion faces a "mission impossible" to retain his World Cup title in Taicang, China, on May 3-4, as he has soared in weight after a three-month marriage break.

"I've gained a lot of weight since my wedding and it was once up to 75 kilograms," Wang told Xinhua at the national team's training camp in Nanjing.

"It was terrible because when I broke the Asian record in 2012, I was only 60 to 62 kg. So in order to get back to the course I have to lose some weight first."

Wang, who claimed bronze at the London Olympics in 2012, has managed to reduce his weight to around 65kg since he resumed training in mid February.

"I have been training more and eating less than my teammates. Staying hungry and hardworking is what I need to do," said Wang. "When I feel hungry, I just drink more water."

However, the 22-year-old knows he still has a long way to go.

"I know I am not 100 percent ready yet. But I still want to give all my best in the upcoming World Cup, hopefully I can help the Chinese team to win the team title," he said.

The year 2013 was unforgettable for Wang because he won the gold medal in the Chinese National Games, the country's premier sporting event and a crucial testing ground for future Olympic champions, and also married his long-time girlfriend.

But the sweet memories were marred by his disappointing trip to the Moscow worlds where he was disqualified when he was leading a star-studded field halfway in the men's 20km race. Wang was so dejected that he even considered retirement after the worlds. Yet he found himself motivated again following a three-month marriage break.

"Now I talk to my wife everyday on the phone. She doesn't want to distract me so she seldom pays a visit. She has always been very supportive and gives me a lot of strength to hang on there," said a grateful Wang.

Wang has already set his eyes on the World Championships next year.

"I believe I can go back to my peak form by the end of the year. The World Cup next month is a short-term goal. The World Championships next year in Beijing is what I really care about. I want to win back what I lost in Moscow," he said.