A child obesity expert from New York's City University, US, has urged London to protect parks and play spaces to avoid losing them 'forever'.

Kimberly Libman, who has undertaken research into childhood obesity in both cities, said New York currently does not have as many green spaces as London for children to play in. Libman told the London Assembly's health and public services committee that once green spaces are lost from built-up areas, it is hard to replace them.

"From [New York's] example, what you have got, you should defend fiercely as once it is gone it has really gone forever," she said. The committee was also told there were no simple solutions to reducing childhood obesity levels in London, with schools and the wider community having a role to play.

Committee chair James Cleverly said: "By listening to experts, studying the evidence and learning from cities like New York, which face similar challenges to us, we may be able to identify ways to drive down obesity rates and improve the health of young Londoners."