Healthy meals offered by fast-food chains are not as healthy as they are believed to be, an Australian analysis has found.
Public health experts have said the research reinforced calls for a junk-food tax, with research also showing a tax would be more effective than promoting healthy eating and exercise.
According to the study less than half the salads available at fast-food outlets were low fat but there was a twentyfold variation in sugar and fat between salads.
The study found not even a single sandwich to be low-salt,.
On an average it contained nearly 2.5 grams - almost half the recommended maximum daily intake of six grams combined with an average of nearly 15 grams of fat.
Elizabeth Dunford, the study leader said people often viewed sandwiches as healthy.
"Consumers don't know at a glance if a sandwich is healthier than a burger, [but] they are going to assume the sandwich is healthier," Stuff.co.nz quoted her as saying.
"But bread is a major contributor to sodium and with processed cheese and meat, it is no surprise they are high in salt," she said.
Outlets should gradually reformulate meals so all had lower levels of so-called "negative nutrients".
"If you just cut them by 50 percent, consumers are not going to like the change. But if all fast-food outlets reduce sodium content by 10 percent, that would make a massive difference," she said.
Moreover, Mike Daube of Public Health Association of Australia said regulation was needed.
"Reducing salt can make a huge difference but it has got to be backed up by regulated targets," he said.