McDonald's is hardly an ideal dining location for anyone struggling to stay slim. But the fast food chain scored a PR coup today when Weight Watchers agreed to endorse some of its products in New Zealand – a move met with outrage by nutritionists and obesity experts.

As part of the deal, which the company says is the first of its kind in the world, McDonald's will use the Weight Watchers logo on its menu boards and Weight Watchers will promote McDonald's to dieters.

The link-up is the fast-food chain's latest attempt to improve its reputation by securing endorsements. In January, to the horror of gastronomes, Italy's agriculture minister, Luca Zaia, helped launch the McItaly range of burgers. For a representative of one of the world's greatest culinary nations to do such a thing was "a sign of the moral bankruptcy of Silvio Berlusconi's government", wrote Matthew Fort in the Guardian.

Several items on the fast food giant's menu – the Filet-O-Fish, Chicken McNuggets and Sweet Chilli Seared Chicken Wrap – have been approved for the Weight Watchers diet in McDonald's 150 New Zealand restaurants. Each meal is worth 6.5 points on the programme, which assigns points to food items and allows dieters to consume 18 to 40 points each day to achieve their goal weight.

McDonald's New Zealand managing director, Mark Hawthorne, said: "We were able to include some of our most popular items because of the many changes we have made over the years.

"For instance, the switch to a healthier canola blend cooking oil means items such as the Filet-O-Fish and Chicken McNuggets contain 60% less saturated fat than six years ago.

Chris Stirk, Weight Watchers' director of business in Australia and New Zealand, said the partnership between the companies reflected "part of our philosophy that you can enjoy life … while still achieving your weight loss goals".

But nutritionists and obesity experts said the menu items were a marketing ploy to lure customers into the restaurant. "It's all about sales," said Jane Martin, senior adviser of Australia's Obesity Policy Coalition. "It implies this food is healthy … when often it is high in fat and salt. Chicken McNuggets are Chicken McNuggets whether it's got Weight Watchers on it or not."

Sian Porter, a dietician at the British Dietetic Association, said: "This sort of initiative should be applauded, but the danger is that someone will go in, choose one of the healthier options and then think: 'Ooh good. Now I'll have an ice cream', which is not the right message."

Weight Watchers and McDonald's in Britain said they had no plans for a similar partnership in the UK.

The fast-food chain, widely criticised for selling a high-calorie, high-fat menu that includes super-size meals, was "making every best effort to generate a change in behaviour, to create an awareness in consumers about making healthy choices", Hawthorne said.

For the past year in the UK, the chain has run a programme linking children's football teams with their local McDonald's restaurant and offering them free kit and equipment.