New Delhi: The state of mind decide how content a person may feel after any meal and how often he is to still feel hungry, according to a study.

The study by Yale University, which appears online in the journal 'Health Psychology', could have implications in the fight against obesity, say researchers.

The research team focused on levels of ghrelin, the 'hunger hormone' in the gut, which stimulates the appetite and feelings of hunger. Ghrelin levels typically increase before meals and decrease after meals. The higher the levels of ghrelin in the system, the more likely a person is to overeat.

The Yale team's research subjects were given 380 calorie milk-shake under the pretext that it was either a 620 calorie "indulgent" shake or a 140 calorie "sensible" shake.

Those who drank what they thought was the "indulgent" high-fat, high-calorie shake had a dramatically steeper decline in ghrelin after drinking it. Those who thought they were drinking the "sensible" low-fat, low-calorie calorie shake had a flat ghrelin response, claim researchers.

The ghrelin response to perceived calorie counts was consistent with what would be observed had the counts actually been that high or low.

"This study shows that mindset can affect feelings of physical satiety," said lead author Alia J Crum of the department of psychology at Yale. "The brain was tricked into either feeling full or feeling unsatisfied."