London: The presence of a protein will help doctors determine which women will be more susceptible to weight gain after quitting a diet.
The discovery opens the way for a simple blood test that would tell a dieter whether she will need help to maintain her new slimline shape.
Researchers from eight European countries, including Britain, analysed the blood of 96 dieters who had already lost weight. Half successfully kept it off, or lost even more. But the others regained the lost pounds, the journal Public Library of Science ONE reports.
Testing their blood for 34 proteins revealed levels of a substance called angiotensin-converting enzyme to be linked strongly to whether a woman`s weight fluctuated or remained stable, according to the Daily Mail.
While dieting, women who later kept the pounds off tended to experience large drops in levels of the enzyme, which is more usually involved in constricting the blood vessels.
However, repeated rapid weight gain and loss associated with dieting can double the risk of death from heart disease, including heart attacks, and the risk of premature death in general.
Susan Jebb, a British expert on the research team, said: "Despite what we might think, people are not bad at losing weight - where they really struggle is in keeping it off."