Fancy a side of fat with your green salad?

They're green and supposedly lean, but pre-packaged salads might not be as healthy as you think.

A British consumer watchdog found some supermarket salads in the UK had the same amount of fat as six Cadbury's Creme Eggs.

Although there's less choice in New Zealand, some contain more fat than a burger, with dressings getting most of the blame.

A Fresh Express Caesar salad, bought at New World, has 14.4g of fat per 165g serving. A Dashboard Diner crunchy green salad, with sesame dressing, bought from Foodtown, has 10.5g of fat per 120g serving.

A McDonald's cheeseburger has 13.4g.

Both supermarket salads had dressing in a sachet on the side, so health-conscious shoppers can control how much they eat.

But other add-ons, such as parmesan cheese and croutons, can "blow bad fat intake", according to nutritionist Nikki Hart.

"When you start jazzing things up, that's when the fat creeps in ... and you've eaten your way into a fat nightmare."

Safe food campaigner and Green Party MP Sue Kedgley believed home-made dressings were the best low-fat option.

"I think a lot of people when they're buying something like salad don't even think to look at the label," she said. "Once you get into pre-packaged industrial food you get industrial additives added to your food."