The gym where Rebecca Roberts trains is in an unremarkable industrial unit in St Helens, Merseyside. The room is small, the ceiling low, the music driving, the equipment incongruously large.

There are the 115kg (253lb) logs she presses over her head and the atlas stones she heaves on to plinths. The heaviest stone she has lifted is 180kg. There are the frames she uses to practise hauling cars, whether a Ford Fiesta or her Honda CR-V. There are the barbells she loads with weights until they are heavy enough for her deadlifts. Her record is 300kg.

Roberts, 29, stands just short of 6ft 4in (1.93 metres), in a black top and her trademark bright leggings, smiling beneath a poster of her standing 10 feet tall, smouldering triumphantly from the wall. When she first learned about the sport of strongwoman eight years ago, she hated her body, didn’t feel it was hers, and her spirit was broken by the loss of her mother, years in the care system and a rape at knifepoint. Her weight had risen to almost 30st (190kg) and she spent her days swathed in a black hoodie and tracksuit bottoms, doing everything she could to hide.

In May 2016, aged 21, she walked into a gym to meet Paul Savage, a strongman competitor she had been messaging online. Their connection was instant. The following month they moved in together and he suggested she try competing. Four months later she was crowned the UK’s strongest woman.

It was the start of an incredible rise. She is currently the UK’s strongest woman, Europe’s strongest woman and the world’s strongest woman. She has won six world titles: two in the world grip championships; two in the natural world’s strongest woman contest; and two in the world’s strongest woman contest.

She lives what she calls a Clark Kent/Superman existence, working from home as a quality assurance analyst, before driving to the gym each night to train for three hours, then competing in arenas around the world. She does everything she can to maintain peak condition: when I call her one Sunday, she is off to a 90-minute massage to keep her body firing. The big question now is whether she can achieve her ultimate ambition: to become the strongest woman who has ever lived.

We sit in the gym reception, rain pouring outside, women lifting eye-bulgingly heavy weights on the other side of the wall. In the arena, Roberts pulls trucks or stands between two falling columns, her arms outstretched, holding them steady like an ancient god. She will give a tiny lift of her chin after an impossibly heavy deadlift, the universal signal to fellow competitors: “Come on then, have a go.” When she wins, she raises her trophy above her head and strides around the arena with a Welsh flag, embodying her personal motto: take up space and know your worth.

But there is another side to Roberts. On Instagram, she shows the funny and vulnerable moments: lifting a massive dumbbell that breaks suddenly in her hands; falling on the floor, lightheaded, after trying to press 120kg above her head. In person, she is friendly and soft-spoken, proud of how quickly her sport is growing. “In this gym, 90% of the time you’ll see more women than men,” she says. “You’ve walked in today and there are four women and not a single man.”

Her training sessions can reduce her to tears. “You have to push your body to the limit. You’re constantly trying to break down barriers for what a human body can achieve.” At the UK’s Strongest Woman competition last year, she won by one point, in a nailbiting finish against her closest rival, Lucy Underdown, tossing a sandbag over her head with a fraction of a second to spare. Underdown was the first woman to perform a 300kg deadlift, says Roberts, and “breaking down that barrier has given all the other women the belief it can be done”. Every year, she says, women are getting stronger.

Roberts grew up in Bangor, north Wales, the middle child of five and the oldest daughter. Her mother was disabled and her father worked three jobs. It was “the best childhood”, she says, with feeling. “We had loving parents, we would go on holiday twice a year. We had everything we could want, and more.” There is a photo of her as a child standing beside Christmas presents piled almost as high as her.

One Sunday when she was 12, everything changed. Her father had gone to work, and her mother was lying on the sofa, where she had spent the night after hurting her foot. The kids went out to play without telling their mum – “cheeky, obviously” – and it was only at lunchtime they noticed something strange.

“We would always have a Sunday dinner and we found it really weird that there were no smells of cooking. So we went in, and my mum was still lying on the sofa.” They tried to wake her. No response. They ran to the neighbours to raise the alarm. Her mother’s heart had failed.

After her death, Roberts’ father spiralled. “It was hard. I had to take over the role of mother to my family, because my dad wasn’t cooking for us, he wasn’t cleaning, he wasn’t washing our clothes, he wasn’t providing for us.” Not that it was his fault, she stresses. It soon became clear he couldn’t work any more.

The neglect affected her school life. “I was coming in dirty, I hadn’t had a shower, my uniform hadn’t been washed. My trainers had holes in them, my school trousers had holes in them, so I was bullied a lot.”

A year and a half after her mother died, Roberts and her siblings – apart from her eldest brother, who could live independently – were in the care of social services. A foster placement broke down and the children were separated. “I was just being passed from care home to care home … There was nobody who was pushing me to do anything good with my life.”

At school, she would write notes to get out of PE. “I was a bigger girl and I hated exercising in front of people, because my bullies were in my class and they would always pick on me for being bigger. I’d always be the last to be chosen in sports. I hated it when the teachers said: choose a partner. I never had a partner.”

In the summer months, however, she excelled at athletics. Her height meant she was chosen for shot put and she set a Welsh record at 14 and excelled in the 200m. But there was no support to keep going beyond that level, so she gave up sport.

During her years in care, Roberts says her suitcases were always “ready to go”. At 16, she was allowed to move into her own house, the first of three she lived in before she was 18. Nothing was permanent or stable. She received £70 a week in benefits, to cover everything; she was worried about her younger brother, so spent some of it to take him to tennis lessons. “I’d still do a Sunday dinner for my family every week, invite them all round to my little house.”

Just a child herself, she had to advocate for her father. He was diagnosed at 46 with Pick’s disease, a form of dementia, and began regressing. He might forget, for instance, that he needed to look before crossing the road. At one point he was discharged from hospital and moved back into the family home, and when she visited she found the electricity had been turned off and there was only mouldy butter in the fridge. So at 16, she says: “I was going to meetings with his consultants, fighting for his right to be looked after and to have the care he needed.” He was eventually moved to a care home where he was well looked after until he died last year, aged 62.

Roberts has stayed close to her siblings, but her teenage years sound incredibly lonely. Her parents had always encouraged her to strive for bigger and better things – her father had been a talented marathon runner, and he and her mum taught her never to give up. But now everything she did was off her own bat. Within the care system, she says, the biggest ambitions for her were that she would get a menial job and stay off drugs and out of crime. “I thought, no. I want something big for my life.”

She decided to go to university and won a place to study forensic psychology and criminal justice at Liverpool John Moores. At her freshers’ fair, she was scouted for the rugby team. “There was another girl who was taller than me and there were people who looked like me. I was like: ‘This is amazing.’ It was the first time I really felt I belonged somewhere. And I found something I loved to do.”

She began playing for the university team and Waterloo Ladies, then a Premiership-level women’s side. Her goal, she decided, was to play for Wales.

But her life was soon upended. In the summer holidays after her first year of university, with no family home to return to, she stayed in Liverpool. One night, she went out clubbing and, having lost her friends and realising her phone had died, she decided to head home. Around the corner from the taxi rank, she was raped at knifepoint.

The police found her on the pavement within 20 minutes of the attack, and she was immediately taken for a forensic medical exam. As a result of her description, her attacker was arrested two or three hours later, still prowling the streets. He denied ever seeing a tall brunette girl, but his DNA was all over her.

Her university friends had gone home for the holidays, so she was alone. She went into a deep depression. “I couldn’t leave the house without having a panic attack. I’d have my phone glued to my hand whenever I left the house, because I could not put it down. Even now, the first thing I always do when I leave the house is make sure I’ve got my phone.”

A few weeks after the attack, she was tackled by two girls on the rugby pitch, and went flying. “I landed on my lower back and did disc damage, ligament damage and nerve damage.” It was so bad she couldn’t walk and was on morphine for six months. “One vivid memory I have from that time is walking around Asda, and I had to sit on the floor in the middle of the shop, and I was crying because I couldn’t do a food shop, even with a trolley, because my back was hurting so much.”

She leant on her family because she had lost a lot of trust in people. “I was single, and I couldn’t do any sport, and I gained a lot of weight, partly because of the injury, but partly because I was going through a lot mentally after the rape … I would just stay in the house and eat myself silly.”

At the time of the attack, she was a size 12 to 14, but a year and a half later, she says, she was a size 28. “In my head, I was like, well, if I’m this big, then I’m not attractive to people, and what happened to me won’t happen again. I just had no self-confidence.”

She kept working towards her degree, because she had promised herself she would complete it. But she felt she had been stripped of her rugby ambitions because of her injuries, and stripped of her social life because of the rape. “I drifted from my university friends, because they were going out drinking, they were enjoying life, and that was something I couldn’t do.” She hasn’t been out clubbing since the attack in 2014.

It took more than a year for her rapist to be sentenced and Roberts says she tried to kill herself at least three times. “I hated myself,” she says, before adding, with understatement: “I was in a bad place.”

On 9 May 2016, she walked into the gym to meet Paul Savage. They had connected on the dating site Plenty of Fish, and she had told him about her rugby days, and how she had gone to the gym to strengthen her game. He was passionate about strongman, dedicated to becoming a top competitor himself. He agreed to be her coach.

It was love at first sight, she says. “As soon as I met him I saw safety and love. I just thought: you are my person.”

She started going to the gym with him four nights a week and staying over at his place. At the end of June, her lease came up. “He just said: ‘Well, move in with me.’ So it was like, either it works, or it doesn’t. And it really, really worked.”

Her back injury was still bothering her, “but he was very, very good with rehabilitating it. He told me: movement is medicine. That was his main motto. He said: ‘We just need to get you moving in the gym, doing the rehabilitation exercises.’ And that’s when he found out I was actually quite strong.”

Another understatement. A few months after they met, he told her she would, without doubt, be the strongest woman in the world within five years. He was convinced she had the potential, could see it in her build and athleticism from her rugby, shot put and 200m sprint days. I ask how she responded, and she laughs. “I was like: ‘Are you being serious?’”

The sport was relatively small at the time. One of the only contests available was UK’s Strongest Woman, so there was no chance to work her way up through local events. Did she think she would do well? “Paul had so much belief in me. It was the first time since I was a young child that I felt that from somebody. Throughout my time in care, there was nobody saying: ‘I believe you can do something great.’ It was always me thinking: ‘No, I can do it, I can do it.’ But having Paul there, he was my cheerleader, he was everything. And he made me believe I could do it.”

Now, the sport takes place in arenas and stadiums before sellout crowds, and there are serious prizes on offer. If she wins her next competition, the Rogue Invitational, in a few weeks’ time, she says she will take home $120,000. She is hopeful that if she keeps on winning she can buy a house and establish the stability she never had as a kid.

Eight years ago, it was very different. That first competition was held in a gym car park. “There were more people competing than watching, and the only people who were watching were family and coaches.” With only four months of training, she won. Her prize was a tub of out-of-date protein powder.

When she entered the World’s Strongest Woman competition in 2019 she came seventh, but by the 2021 contest she was in a different shape and mindset. While she recognises how terrible Covid was, she says it gave her time “to just learn to love myself”. As a result of training, going for walks every day, eating properly and being free of some of the usual stresses, she lost 9st. In 2019, she notes, she was dressed all in black. By 2021, she was wearing her bold leggings and looking much happier. She won the competition.

Savage’s astonishing prediction had come true. In just five years, she had become the strongest woman in the world, still in her mid-20s. As a result of extraordinary talent and ceaseless work, she had beaten all comers.

The celebrations didn’t last. In March 2022, Savage suffered heart failure. He was in hospital for two weeks, after which his heart began to improve. But on the morning of 4 December 2022, the couple were in bed, when he let out a gasp and stopped breathing. “I rang 999, dragged him out of bed and gave him CPR. It was the worst morning of my life. Nobody prepares you for that.” There was nothing she could do. A postmortem showed his left ventricle had thickened. He was 36.

The day before Savage died, he had been emailing the organisers of the Arnold Sports Festival in Ohio – a prestigious annual competition named after Arnold Schwarzenegger – to secure Roberts a place. On the day of his funeral, she received her invitation. “After Paul passed away, I just dedicated myself to the gym,” she says. “Every competition, he used to tell me to be strong, so I’ve got a necklace with his ashes in it that comes with me. Every podium picture you’ll see I’m wearing my necklace and engraved on the back is ‘be strong’.” She says everyone would have understood if, after his death, she had “wasted away my life in grief. But instead, I’m sitting here the current UK’s, Europe’s and world’s strongest woman. Which life would you want?”

I ask what Savage was like. “To the outside, he was very shy, very much an introvert.” But to people he knew well: “He was so loving and caring, funny and supportive. Throughout my entire strongwoman career, he wanted to be a strongman himself, but he put that to one side to support me to do great things … He put his dreams aside for me to achieve mine. He was so selfless.”

The Rogue Invitational is in Aberdeen in November and the World’s Strongest Woman in Wisconsin in December. So she is doing her workouts and stretches, focusing on her nutrition and hydration, getting every twinge checked out by the physiotherapist and helping her body recover with the hot and cold tubs she has installed at home.

As Savage used to say: “An uninjured Rebecca is an unstoppable Rebecca.” She will soon find out whether he was right about that too.

What would it mean for her to become the strongest woman who ever lived? “For me, winning five World’s Strongest Woman titles,” she says. The record of four is held by the Polish athlete Aneta Florczyk, who won the titles between 2003 and 2008. “But to be honest, without sounding horrible, she did that at a time when there wasn’t really anyone competing in the sport. Now, versus then, it’s so much harder to win a World’s Strongest Woman title.”

Roberts mentions the British competitor Donna Moore, who has won the contest three times, most recently in 2019 at 39. “You don’t really reach your peak age, peak strength until you’re in your mid- to late-30s. I’ve still not hit 30 yet … and I’ve got two. So there is time.”