Frankie Gavin was sent home before last summer's Olympics in near disgrace after failing to make the weight. But the real story was not of a man who failed through lack of effort; Gavin's Olympic experience was one of fasting, saunas and endless training. He now feels that his health was put at risk in the team's pursuit of gold medals.

When Gavin, 22, flew back to England from the Great Britain holding camp in Macau the day before the Games began in Beijing, he found himself accused in some quarters of letting the country down and wasting taxpayers' money. As the country's first world amateur champion, he was favourite for the gold medal; he did not even pull on a pair of gloves.

Yesterday, for the first time, he told his side of the story. He said that he had asked to move up in weight 13 months before the Beijing Games, but was denied the chance of a box-off for the light-welterweight (64kg) position. When he won the world amateur title at lightweight (60kg) in Chicago in November 2007, his fate was sealed. He tried his best and more, but the final 3lb did not shift. He had simply outgrown the weight.

“All I was thinking about was the Olympics,” Gavin said. “I would have these sessions where I was in the sauna in a sweat suit running on the spot and punching for 20 minutes, then coming for a break. It was really bad and I wasn't going to the toilet.

“I wasn't ill but I felt really weak. The last session I did I just couldn't move in the gym. I tried to hit the bag but I had nothing left. I was probably relieved at the time, I just knew I couldn't do it. I had a drink and that's when it sunk in. That night I had two puddings with dinner.”

Gavin has now turned professional with Frank Warren, the promoter, along with James DeGale, the middleweight gold medal-winner in Beijing, and Billy Joe Saunders, the welterweight member of the team. Tony Jeffries, who won a bronze medal at light-heavyweight, has signed with Dennis Hobson. “In the pros, they treat you like an adult,” he said. “In the amateurs, they talk down to you. When I struggle in the pros, I'm just going to go up in weight.”

Gavin says that his problem was long known. “I struggled for the Commonwealths in 2006,” Gavin said. “Before the worlds, I asked for a box-off for the 64kg spot and Terry Edwards [the head coach] said no.

“Before the worlds, I was walking around at 67kg. I'd make the weight in the morning, after the fight I'd be 63kg, I'd train for 1 to 2 hours to get under 60 and go to bed without eating. Four days on the trot I did that.”

The gold medal in Chicago meant that he had qualified for Beijing, but at lightweight, with no option to switch division. “Coming back from the worlds, I knew I had a hard year ahead of me,” he said. “I was walking around at 70kg by then. I just grew. I wanted to turn pro, but my amateur coach thought I could make it. He wasn't in China with me, so he never knew how bad it was. When you win, you think about all the glory, you don't think about how hard it all was. Terry Edwards knows what I went through.”

When the weight did not shift, Gavin quit the team at their training base in Sheffield a fortnight before the Games, but was persuaded to return. His absence was explained as “flu”.

“I was 64kg after training and I was ripped,” he said. “There was nothing on me at all. I killed myself to make 64kg for the EU Championships [in June]. I won gold and won boxer of the tournament. I think I would have won the Olympics at 64kg.

“They just want medals, don't they? I lost all my trust in them. Before the Olympics they were all over me because I was winning tournaments. When you lose, they are not there for you. All the lads will tell you that, but I didn't really see it - I was always winning. I haven't lost in three years.”

When the other seven team members went to Beijing, Gavin was left in Macau. “Those last two days were really hard,” he said. “I was running for an hour in a sweat suit in the heat across sand. Making me do sprints when I had nothing in me. The last few days I had a little bit of rice, some fish and some chicken. I was hardly eating anything.”

He believes that Edwards should stay in charge of the GB team. “I have nothing bad to say about his coaching,” he said. “I did my best and it wasn't enough. I'd rather forget about the Olympics and think about winning a world title as a pro. It didn't take away my enthusiasm. I love boxing and want to do my best.”

And the chances for the next generation in 2012? “It depends how they treat the kids,” he said. “Or they might not have a team.”