But why did they underreport ?

但是他们为什么少报呢？

Some studies suggest people underreport their caloric intake by 30 percent or more.

某些研究也表明：人们实际上吸收的卡路里比他们认为的要多出30％或者更多。

People tend to underreport the amount they spend on alcohol and cigarettes, for instance.

例如,人们倾向于少报他们发在喝酒和吸烟上的金钱.