One of the myriad reasons smokers cite for not wanting to quit is that they fear they might gain weight because cigarette smoke keeps them thin. Now, a new study challenges that belief by suggesting that exposure to cigarette smoke actually causes weight gain, and for non-smokers, secondhand smoke enhances this effect.

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The new study challenges the belief that cigarette smoke exposure keeps individuals slim, instead asserting that it actually causes weight gain by triggering a mechanism that impairs the cells’ response to insulin.

The researchers, from Brigham Young University (BYU) in Provo, UT, publish their findings in the American Journal of Physiology: Endocrinology and Metabolism.

It is already well known that smoking carries with it risks to health. But for those who do not smoke, secondhand – and even thirdhand – smoke poses certain risks.

Medical News Today recently reported on a study that suggested non-smokers who live with smokers are exposed to three times the healthy limit of dangerous air particles recommended by the World Health Organization.

According to the researchers of this latest study, half of the population in the US is exposed to secondhand smoke at least once daily, and around 20% of young children live with smokers.

“For people who are in a home with a smoker, particularly children, the increased risk of cardiovascular or metabolic problems is massive,” says Prof. Benjamin Bikman, study author from BYU.

Additionally, nearly 4,000 young adults in the US smoke their first cigarette every day, and 1,000 become habitual smokers.

Prof. Bikman and his BYU colleague, Paul Reynolds, were interested in how cigarette smoke affects metabolic function. Specifically, they wanted to identify the mechanism behind why smokers become insulin resistant.

As such, they carried out an animal study using mice who were exposed to secondhand smoke and followed their metabolic profiles throughout.

From an observational standpoint, the researchers found that the mice exposed to smoke put on weight, and when they analyzed the cellular level, they discovered that the smoke triggered a lipid called ceramide to change the mitochondria in the cells, disrupting normal cell function and impairing the cells’ response to insulin.

From this finding, the team discovered that the key to reversing cigarette smoke’s effects is to inhibit ceramide.

Commenting on their results, Reynolds says:

The lungs provide a vast interface with our environment and this research shows that a response to involuntary smoking includes altering systemic sensitivity to insulin. Once someone becomes insulin resistant, their body needs more insulin. And any time you have insulin go up, you have fat being made in the body.”

When they treated mice with myriocin – which is a known ceramide blocker – the researchers observed that they did not gain weight or exhibit metabolic problems, whether or not they were exposed to the smoke.

Interestingly, however, when the mice exposed to smoke were also fed a high-sugar diet, myriocin could not fix the metabolic disruption.

The team is currently seeking a ceramide inhibitor safe for human use. “The idea that there might be some therapy we could give to innocent bystanders to help protect them from the consequences of being raised in a home with a smoker is quite gratifying,” says Bikman.

In October of this year, MNT reported on a study published in JAMA Internal Medicine, which suggested that 14 million major medical conditions in the US are due to smoking.

And yesterday, we reported that smoking is linked to an increased risk of chronic back pain.