Most people underestimate the number of calories in fast food, and the problem is growing as meal portions get larger, according to a new study reported on by the Associated Press.

People make more accurate guesses when the meals are smaller, according to the results of the study being published Tuesday in the Annals of Internal Medicine.

The study was conducted in two parts, according to AP. First, researchers asked 105 people eating at fast-food restaurants in three Midwestern U.S. cities to estimate the number of calories in the meals they had just eaten.

In the second part of the study, 40 undergraduate students were asked to estimate the calorie content of 15 various sizes of fast-food meals. The meals, ranging from 445 to 1780 calories, consisted of varying amounts of chicken nuggets, fries and soda.

The results were similar no matter how much the participants weighed or whether they were male or female, the researchers found. However, overweight people in the first part of the study tended to buy larger meals.

So how do we avoid overeating at fast food places? Researchers suggest using smaller plates and downsizing meals when eating out. You can also divide food into separate groups to try to figure out the calories.

And if you're really at a loss, just bag up half of the food and eat it later. Then, you're guaranteed to eat less.

-- Amanda Barrett, amNY.com