Scientists have identified a seaweed fibre that prevents the body absorbing fat.
Tests show that alginate, found in sea kelp, can suppress the digestion of fat in the gut.
Researchers investigated the ability of alginate to reduce fat break-down by a digestive enzyme, pancreatic lipase.
Blocking the action of the enzyme results in lower amounts of fat being absorbed by the body.
Lead scientist Professor Jeff Pearson, from the University of Newcastle's Institute for Cell and Molecular Biosciences, said: "We have already added alginate to bread and initial taste tests have been extremely encouraging.
"Now the next step is to carry out clinical trials to find out how effective they are when eaten as part of a normal diet."
The researchers compiled a list of the most promising seaweeds, including a brown sea kelp known as "tangle"or "cuvie", bladderwrack, and bull kelp.