From flip flops to fisherman's sandals: How to look after your feet this summer

"In terms of arch support and joint support, it's not the best style, but people are investing a bit more, getting their flip-flops customised, because it's something that is just so easy to wear," Baidoo says.

Podiatrist Dr Helen Branthwaite, who is also chief clinical adviser at the Royal College of Podiatry, says it's "not accurate" to say flip-flops are bad.

The problem comes if you go straight from wearing a very structured shoe to wearing flip-flops a lot, she explains. It means your foot is under more strain than normal, which makes you more prone to injury.

"The foot does start to change shape and tends to splay a little bit over time," says Branthwaite.

"A good analogy is if you were to wear a corset all the time and then took the corset off, everything would sort of all hang out, so to speak."

So what are the stylish and comfortable alternatives?

Reporting from BBC News contributed to this story.