Child obesity is a "ticking time bomb", according to experts, with one in three children overweight by the time they leave primary school.
There has been a big focus on how the government can tackle the issue - for example, next month the sugar tax comes into force.
But a report from the charity arm of the world-famous Guy's and St Thomas' hospitals shows what can be achieved locally in urban areas.
More than half of meals eaten outside the home come from takeaways and one fast food shop in the London Borough of Haringey has launched a range of healthier options including grilled chicken and baked potatoes.
Staff at Tasters are trained to encourage young people to choose the new options and flyers and posters are being distributed locally to promote the menu.
It is part of the Healthy High Streets Challenge, which is inviting people and businesses to think of new ways to make the food on offer more affordable.
Parks on demand
Today, one-fifth of children regularly play outdoors, compared with nearly three-quarters of their parents who did so when they were youngsters.
Finding the space to do that in towns and cities where the streets are busy with traffic can be a challenge.
But the Pop up Parks project is changing that. The group works with councils to set up temporary parks in streets and squares encouraging children to come outside and play.
It has also linked up with town planners to design innovative play areas in small urban spaces.
And Pop up Parks is encouraging others to follow its lead and set up their own play areas and share them online.
Promoting a healthy lifestyle at school
Surrey Square Primary School in south-east London looks to encourage pupils to adopt a healthy lifestyle in everything that they do.
Healthy school meals are an obvious starting point, but the school also enforces a healthy policy on packed lunches - no fizzy drinks or sweets are allowed.
PE is a core part of the national curriculum, but the school has gone further and has sports coaches on patrol during playtime to encourage children to be active and work with some of the older pupils to instigate games.
Surrey Square co-head Liz Robinson says schools "can't do everything", but can certainly play their part.
Fruit and vegetable vouchers
The Alexandra Rose Charity works with children's centres and local market stall holders, offering families on low incomes vouchers to buy fresh fruit and vegetables.
The vouchers are worth £3 per child per week - double for those under the age of one.
The biggest scheme is in Barnsley where families collect the vouchers on Wednesday from libraries and are also given advice and tips at their local children centres on healthy meals they can cook at home.
More than 240 families are signed up.
Jonathan Pauling, the charity's chief executive, says it is a "really simple, but effective way" of getting young families to eat more fresh produce as well as having the benefit of supporting local businesses.
'Time to work together'
Kieron Boyle, chief executive of the Guy's and St Thomas' Charity, says: "Our report shows that everyone needs to play a role. The places our children grow up - our homes, schools and streets - are influenced by many different people.
"We will succeed by bringing them together and creating environments that make the healthy thing to do, the easy thing to do."
The charity has been given the backing of Public Health England.
Chief nutritionist Dr Alison Tedstone says "tackling obesity is everyone's business".