(CNN) Twice as much food as previously estimated -- or a third of all food available for human consumption -- is wasted, with people in wealthier countries wasting more, according to a recent study published in the journal PLOS One.

Researchers looked at the relationship between food waste and wealth and found a direct link between the two. They also discovered that people in poorer nations begin wasting more food as they earn more money.

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The study estimated food waste using consumer expenditure and found that, globally, people were wasting as much as 727 calories a day in food in 2011, or 25% of calories available for human consumption, compared to 351 calories a day in 2003, although researchers said the 2003 measure did not include food waste from some of the largest nations, such as the United States, so they recalculated food waste for the year 2005 at 526 calories a day per capita.

Researchers said that food waste is not a "problem at low levels of affluence," or in developing countries, and that a so-called "elasticity" or growth in waste occurs as incomes increase.

The "affluence elasticity of food waste" is a new concept from this study that finds food waste increases quickly at first, then the increase "tapers off" as wealth grows.