Some people swear that smoking cigarettes keeps them slim.

But being exposed to cigarette smoke can actually make people pile on the pounds, new research shows. 

And it is innocent victims of secondhand cigarette smoke are the most likely to gain weight.

'For people who are in a home with a smoker, particularly children, the increased risk of cardiovascular or metabolic problems is massive,' said lead author Professor Benjamin Bikman, of Brigham Young University in Utah.

Passive smoking damages the body because second-hand smoke contains more than 4,000 chemicals, many of which are irritants and toxins, and some of which are known to cause cancer.

Data shows half of the U.S. population is exposed at least once daily to secondhand cigarette smoke and approximately 20 per cent of young children live with someone who smokes in the home.

In the UK, it's estimated that second-hand smoke kills over 12,000 people every year from lung cancer, heart disease, stroke and the lung disease Chronic Obstructive Pulmonary Disease (COPD).

Professor Bikman, and his co-author Professor Paul Reynolds, wanted to investigate how cigarette smoke is tied to metabolism.

参考译文：
吸烟和二手烟的危害早已经广为人知。

有人声称吸烟可以帮助减肥。一项新研究结果证明，吸烟不但不能帮助减肥，反而可致肥胖，而二手烟受害者更为显著。

美国犹他州杨百翰大学的本杰明Bikman领导的团队通过实验研究找到了吸烟引发胰岛素抵抗，从而导致体重增加的机制。在研究中，他们让小鼠暴露于二手烟来分析了它们的代谢进程，并得到了预期的结果——暴露于烟雾中的小鼠长胖了。

研究人员进一步在细胞水平上分析发现，烟雾触发一种被称为神经酰胺的微小脂质改变细胞中的线粒体，这造成正常细胞功能障碍，并抑制细胞对胰岛素的响应能力。也就是说，被动吸烟可改变身体对胰岛素的敏感性，造成胰岛素抵抗，导致身体需要更多的胰岛素。胰岛素水平的升高则导致身体脂肪的集聚形成肥胖。

研究人员发现，逆转香烟烟雾这种影响的关键是抑制神经酰胺。进一步研究发现，用一种已知神经酰胺阻滞剂——多球壳菌素治疗的小鼠，无论是否暴露于烟雾，均没有出现代谢问题和肥胖。然而，当暴露于烟雾的小鼠同时喂食高糖饮食，代谢干扰则不能被防止。

Bikman教授和他的团队正测试神经酰胺酶抑制剂在人体使用的安全性问题。

研究者表示，有希望开发一种为无辜的二手烟受害者提供保护的治疗措施。但是对于吸烟者本人却没有“保护疗法”可用，他们唯一可以做的就是戒烟。这或许会给瘾君子提供戒除烟瘾的一种新动力。