"If you put it on your plate, it's going into your stomach," said Brian Wansink, Professor of Marketing and Director of the Cornell Food and Brand Lab.
Wansink and co-author Katherine Abowd Johnson analysed 1,179 diners and concluded that we are a 'Clean Plate Planet'.
Although diners were analysed in eight developed countries, the US, Canada, France, Taiwan, Korea, Finland, and the Netherlands, the results were nearly identical.
If we serve it, we'll eat it regardless of gender or nationality, researchers said.
"Part of why we finish most of what we serve is because we are aware enough to know how much we'll want in the first place," said Johnson.
The finding, however, did not hold true for children. Analysis of 326 participants under 18 years old, showed that the average child eats only 59 per cent of what he or she serves.
"This might be because kids are less certain about whether they will like a particular food," said Wansink.
"Regardless, this is good news for parents who are frustrated that their kids don't clean their plate. It appears few of them do," he said.
Wansink said the findings, published in the International Journal of Obesity, can positively impact an individual's eating behaviour.
"Just knowing that you're likely to consume almost all of what you serve yourself can help you be more mindful of appropriate portion size," Wansink said.