The study found that the stomach nerves which convey signal of fullness to the brain become irreversibly desensitized following a high-fat diet, especially if such a diet is consumed for a long period.
Such high fat diets destroy the way the hormone leptin functions and this alters the sensitivity of the stomach nerves that regulate intake of food.
"These two mechanisms combined mean that obese people need to eat more to feel full, which in turn continues their cycle of obesity. The stomach's nerve response does not return to normal upon return to a normal diet. This means you would need to eat more food before you felt the same degree of fullness as a healthy individual," said the study leader, Amanda Page, from the University of Adelaide.
"We know that only about 5 per cent of the population actually manages to maintain weight loss after they've gone on a diet.They in fact actually gain within about two years plus some more. So we just wanted to look and see why this was," study authors said.