Recipes by prominent TV chefs are less healthy than supermarket ready meals, Newcastle University researchers say.
Meals by Jamie Oliver, Lorraine Pascale, Nigella Lawson and Hugh Fearnley-Whittingstall were compared to those from Asda, Sainsbury's and Tesco.
The meals in TV chefs' cookbooks contained more calories, fat, saturated fat and sugar - but less salt.
The researchers said this was not about "bashing" chefs as many campaigned to tackle obesity.
The team said it was widely agreed that cooking from scratch was healthier than buying prepared meals, however, they said there was a lack of scientific testing of the claim.
In the study, published in the British Medical Journal, they compared 100 main meals from four TV chefs, who had books at the top of the bestseller charts, to 100 supermarket ready meals. These were then compared to nutritional guidelines set by the World Health Organization.
On average, meals in the chef's books were less healthy and "more likely to achieve red traffic light labels", the researchers said.
Prof Martin White, from the Institute of Health and Society at the university, told the BBC: "Both ready meals and those by TV chefs are not as healthy as they could be.
"We're not bashing TV chefs, among them are chefs that have done a huge amount for healthy eating and tackling obesity."
The study does not attempt to look at how often the meals are cooked - if they are part of people's daily diets or just dishes for a special occasion.
However, the researchers did call for chefs and publishers to put nutritional information alongside their recipes in cookbooks to allow budding chefs to make a more informed choice about the nutritional content of their meals.
"Educating and informing consumers should apply as much to TV chefs as for food in shops," said Prof White.
A spokesman for Jamie Oliver said: "We welcome any research which raises debate on these issues.
"We would regard the key issue to be food education so that people are aware of which foods are for every day and which are treats to be enjoyed occasionally."
They added Jamie's most recent book already had nutritional information per serving.
A spokeswoman for Lorraine Pascale said: "Some of the recipes in Lorraine's book are healthy, some not quite so much so.
"There are plenty of salads, soups and light meals as well as the richer dishes.
"Her books and shows to date haven't been about healthy eating, they are about cooking."
Supermarkets said they had been making their food healthier.