Seaweed could hold the answer to tackling obesity, according to Newcastle University researchers.
The team found alginate - a fibre found in sea kelp - reduces the body's fat uptake by more than 75%. That is better than most anti-obesity treatments.
Now the fibre is being added to bread in an effort to develop foods that help lose weight.
Clinical trials are now intended to find out how effective it would be in a normal diet.
Dr Iain Brownlee, who co-led the Tyneside team, said: "This research suggests that if we can add the natural fibre to products commonly eaten daily, such as bread, biscuits and yoghurts, up to three quarters of the fat contained in that meal could simply pass through the body.
"We have already added the alginate to bread and initial taste tests have been extremely encouraging."
The scientists used an "artificial gut" to test the effectiveness of 60 different natural fibres by measuring the extent to which they affected the digestion of fat.
The findings have been presented at the American Chemical Society's spring meeting in San Francisco.
"There are countless claims about miracle cures for weight loss but only a few cases offer any sound scientific evidence to back up these claims," said Dr Brownlee.
"Obesity is an ever-growing problem and many people find it difficult to stick to diet and exercise plans in order to lose weight.
"These initial findings suggest alginates could offer a very real solution in the battle against obesity,"
Alginates are already used in small amounts in food as thickeners and stabilisers.
Dr David Haslam, chair of the National Obesity Forum, said: "Some products are sold as medical devices at vast expense which simply don't work.
"This looks interesting, but we could only start recommending it if the scientists were able to provide good evidence based on rigorous trials."