Americans Mistaking Package for Portion

SARATOGA SPRINGS, N.Y. - At 170 calories per serving, Kathryn Mora figured the spaghetti was harmless. So she slurped away, eating her fill. A closer look at the nutrition label destroyed all those warm comfort food feelings: A serving was just an eighth of the box - not the whole thing.

"I can eat the entire box, like that," said Mora, snapping her fingers.

A common pitfall when checking nutrition labels is failing to factor in serving size, according to a small study by Vanderbilt University researchers. And even when people do, they often miscalculate how much they're eating. Americans' inability to understand portion control is one reason cited for the country's …