Researchers say our appetite is influenced by an array of factors including eating environment and the perception of the food in front of us.
Previous studies have shown that eating in front of the TV can increase both hunger and the amount of food consumed, and people's food intake appears to be susceptible to their surroundings like the eating behaviour-and body size-of their dining companions.
Even simple visual cues, like plate size and lighting, have been shown to affect portion size and consumption.
The new study adds a new wrinkle by suggesting that our short-term memory also may play a role in appetite.
Several hours after a meal, the study found, people's hunger levels were predicted not by how much they had, but rather by how much food they'd seen in front of them-in other words, how much they remembered eating.
For the study, researchers in the U.K. showed 100 adults a bowl containing either a small (10-ounce) or a large (17-ounce) serving of tomato soup, and asked them to eat the whole portion.
However, half of the participants ate more or less than their eyes led them to believe, thanks to a concealed tube that imperceptibly refilled or drained the bowl.
Immediately after the meal, the participants' hunger levels depended on the amount of soup they had consumed. Those who had eaten the large serving were more likely to report feeling full-a predictable response to the signals sent out by the stomach and gut following a meal, the researchers say.
Two to three hours later, however, the participants' feelings of fullness were related only to the perceived amount of soup consumed.
Regardless of how much soup they had actually had, those who believed they consumed 17 ounces reported being less hungry, on average, than those who thought they consumed 10 ounces.
According to Jeffrey M. Brunstrom, lead author of the study from the University of Bristol, this time-based disparity suggests the memory of our previous meal may have a bigger influence on our appetite than the actual size of the meal.
"Hunger isn't controlled solely by the physical characteristics of a recent meal. We have identified an independent role for memory for that meal," Fox News quoted Brunstrom as saying.
"This shows that relationship between hunger and food intake is more complex than we thought," he added.
The study has been published in the journal PLoS ONE.