Sarah Thomas drank the equivalent of eating 46.4kg of potatoes, or 21.6kg of pasta, over the course of her swim over 54 hours.

Sarah Thomas, who had treatment for breast cancer in November last year, has become the first person to swim the English Channel four times without stopping.

The 37-year-old dedicated her record swim, which took more than 54 hours, to “all the survivors out there”. Sarah Thomas feared at one stage that her cancer treatment might stop her ultra-marathon swimming.

The English Channel is about 21 miles (34 km) wide, according to the Channel Swimming Association, and the woman from Denver, Colorado swam from England to France and back twice. It is a remarkable feat that has never been done before by a man or a woman.

The swim by Sarah Thomas should have been a total distance of about 80 miles (129 km) but the tidal pulls in the Channel increased the distance by more than 60%, meaning Wilson ended up swimming nearly 130 miles (209 km).

It was not only a strong current that Thomas had to contend with. She endured salt water drying out her throat and jelly fish stings on her face.

Her nutrition was a special sports drink, CarboPro, designed for endurance athletes and further infused with electrolytes and caffeine.

Legal in professional competition, the makers claim that one serving (50g) mixed with water “represents theoretically as much carbohydrate content as 200g of cooked pasta; or as much as 430g of potatoes.”

Thomas drank a bottle of CarboPro every half an hour: the equivalent of eating 46.4kg of potatoes, or 21.6kg of pasta over the course of her swim. A bottle was hung from a boat for her to grab and drink it.

The caffeine would have helped her say awake, but Eddie Spelling, captain of her support vessel, said Thomas’ body and mind played a huge part.

Sarah Thomas, 37, is about to change her googles from day to night wear.

“Some swimmers can actually sleep in the water, but Sarah didn’t do that,” Spelling told The Telegraph.

“She is a supreme athlete who goes into a different realm of consciousness when she’s in the water.

“The human body is an incredible physical machine but Sarah had a mental state beyond compare. It is only through sheer bloody-mindedness and determination that she could do what she did.”

Scientist Beat Knechtle, a doctor from Switzerland, found that women are physiologically better suited to endurance events than men.

Looking at 30 years worth of finishing times at the 28.5 mile Manhattan Island Marathon Swim, he found that on average, the best women were 12 to 14 percent faster than the best men.

“Women have an advantage due to their higher body fat, which provides insulation against the cold and better buoyancy,” he told the Financial Times.

When Thomas got out of the water she drank champagne and munched on M&Ms.

“It didn’t go down very well,” she said.