A total of 500 fast food takeaways in London have signed up to an initiative that encourages them to sell healthier food.
The Mayor of London Boris Johnson also announced that JJ Food Service, one of the largest suppliers of food to takeaways, is now promoting the Healthier Catering Commitment to the 13,000 restaurants it counts as customers.
The move comes as recent research in Tower Hamlets revealed one fast food takeaway selling a portion of chips totalling 1,865 calories, 93% of daily recommended intake, and 69g of fat.
The research also showed that portion sizes are increasing as takeaways compete for custom.
Meanwhile, Londoners living or working close to clusters of takeaway outlets are twice as likely to be obese and more likely to eat unhealthy food. Over half of the adult population in London is either obese or overweight.
Since 2012, Johnson has supported environmental health and public health teams to deliver the Healthier Catering Commitment for London. 500 restaurants in 22 boroughs have signed up to the voluntary scheme that incentivises food outlets to make small changes to improve the quality of the food they sell.
Johnson said: "It is terrible that as a city, and indeed as a nation, we are getting fatter. Throughout my mayoralty I've invested in grassroots sports and food programmes to get Londoners healthier and fitter, but we still need to do more to tackle our expanding waistlines.
"Life in a busy city means that we inevitably enjoy fast food, while takeaway businesses make a great contribution to local economies and this scheme ensures takeaway food can be a healthier option."
Rosie Boycott, chair of the London Food Board, said: "Getting JJs on board is a massive step forward for the Healthier Catering Commitment and I am encouraged that they are taking a lead to change the terrible health outcomes of so much of London's fast food.
"However, I would like to see even more changes to how takeaways operate. In some parts of the capital there are up to 40 fast food takeaways within half a mile of schools and many of them entice children by cutting their prices at school leaving time. Sadly, we can do nothing to stop that and at the moment all action is voluntary, but this must change in the future."
To help make London's takeaways healthier, JJ Food Service will offer a 10% discount off five Healthier Catering Commitment items for three months to customers who are signing up to the Healthier Catering Commitment.
Terry Larkin, group general manager, JJ Food Service, said: "We are delighted about our partnership with the London Food Board and the Healthier Catering Commitment. Through making some changes to the menu as well as increasing healthier options available, we want to encourage fast food businesses to purchase healthier products which, in turn, we hope will have a positive impact on what customers eat."
The Healthier Catering Commitment is a voluntary scheme for food outlets in London to encourage them to improve their food offering. Participating restaurants, such as the Valley café in Charlton, are awarded with the HCC logo.
Mehmet Manyera, owner of the Valley café, said: "Diversifying my food and including healthier options has proved good for my business. Customers I've advised on changing their orders have remained regulars and now I'm looking for further advice on how to suggest and provide healthy alternatives."