Before, research usually depended on national health surveys in which people often reported their weight as less than it really was.

以前，研究通常依靠美国国家健康调查，但人们在调查中往往会少报体重。

One way to do this is by making ways for individuals to make our voices heard, like public health surveys or consultations.

做到这一点的一个方法是让个人有机会让我们的声音被听到，比如公共健康调查或咨询。

And these figures may even be low as it’s likely that many heroin users simply don’t take part in health surveys.

而且这些数字甚至可能很低，因为许多海洛因使用者可能根本不参加健康调查。