Quitting smoking makes you fat, and now scientists know why

istockphoto

(CBS) As often happens in science, it was an accidental discovery. It solves the mystery of why a lot of people who smoke look so skinny and, more importantly, why many people who quit the habit gain weight.

"Interestingly, initially we were not looking into feeding behavior but depression," says Yann Maneur, an associate research scientist at Yale. "We were trying to find new drugs to treat depression. And as I was testing these new drugs I realized the animals were not eating as much."

At the time, Mineur and his team were testing nicotine. Curious about this unexpected effect, they looked further. Maneur says, "We found that nicotine, when it enters the brain, activates specific nicotine receptors that are located on specific neurons known to decrease feeding and increase energy expenditure when activated."

So nicotine, it turns out, triggers a brain pathway that essentially tells you: you've had enough, put that cake down. And it signals your body to start using up some energy. But does that mean people should use it to try to lose weight? "That's the trick question," Mineur says with a chuckle, "because we do not want to advocate smoking, of course."

There may be alternatives that could do the same trick. Maneur claims that there is potential for "drugs to mimic this effect to help people maybe lose weight. Or even better, when people try to quit smoking they could use drugs that are already available and known to trigger this pathway in order to potentially limit their weight gain."

The smoking cessation drug cytisine, which is sold in Eastern Europe, also triggered this brain effect on eating in this study. Developing specific drugs to do the same thing could prove to be tricky, though. The same receptors that react this way to nicotine help control the way the body deals with stress.

This study is reported in the journal Science.

[SallyAnneCulpepper]

Here I am.....I quit July 17, 2011 THREE (3) THREE packs a day for over a year (before that a heavy pack and a half for many many years, 30 at least) brought on by chronic stress for the past couple of years.

Okay, I quit cold turkey (I used Melatonin) and have done fine, I quickly began eating more healthy than ever; gave up dairy, diet coke, meat. Started to eat oatmeal EVERY morning w/ flaxseed, drinking 1/2 galloon of water...reading labels and doing all I can, eating wilted greens for dinner with black beans...What could be healthier??

I also began walking in July and am up to 10 miles a day...but I have only lost 3 pounds in TWO months!!!

And I am low on mental and physical energy too. Today I took a Vicks Day Quil to geta boost. I also take two excederin for the caffine every morning ( but I don't think they are doing anything.

The last time I quit smoking I gained 40 pounds......And I DID NOT use food as a replacement.

I need Support and on top of it all......WINTER is coming so goes my walking! I do not want to start smoking again...I am afraid of my future attached to an oxygen machine and COPD.

I could use the kind of help Kirstie Alley got!!

[DesireeMH]

Dealing with the same thing here. Been quit two years. Spent summer nights walking. I have a physical job. Working out at the gym after work. I cant lose weight no matter what I eat. I might as well junk it up. It makes no difference. I never had this problem until I quit smoking.

[telsie]

"'That's the trick question," Mineur says with a chuckle, "because we do not want to advocate smoking, of course.'"

What's so tricky about it? Nicotine has been so heavily correlated with smoking for so long that people forget they are not synonymous. There are plenty of other forms of nicotine that don't pose any significant health concerns: nicotine gum, nicotine lozenge, nicotine patch, nicotine mist (inhaler or nasal spray), nicotine vapor (electronic cigarette), even swedish snus... All of those are WAY safer than smoking and readily available.

[telsie]

Sorry about the triple post! It kept saying it didn't submit because of site maintenance.

[telsie]

"'That's the trick question," Mineur says with a chuckle, "because we do not want to advocate smoking, of course.'"

What's so tricky about it? Nicotine has been so tightly connected to tobacco cigarettes for so long that people forget they are not synonymous. There are plenty of other sources of nicotine that don't pose any significant health concerns: nicotine gum, nicotine lozenge, nicotine patch, nicotine mist (inhaler or nasal spray), nicotine vapor (electronic cigarette), even swedish snus... All of those are WAY safer than smoking.

[telsie]

"'That's the trick question," Mineur says with a chuckle, "because we do not want to advocate smoking, of course.'"

What's so tricky about it? Nicotine has been so tightly connected to tobacco cigarettes for so long that people forget they are not synonymous. There are plenty of other sources of nicotine that don't pose any significant health concerns: nicotine gum, nicotine lozenge, nicotine patch, nicotine mist (inhaler or nasal spray), nicotine vapor (electronic cigarette), even swedish snus... All of those are WAY safer than smoking.

[vielmann]

I know of plenty of fat smokers that over indulge quite often. Silly story. The truth is that it's about addiction. Replace one addiction with another.

[richlala]

People I know who have been thin forever are now fat after they stopped smoking. It is very true that they gain weight and some of them gain lots of weight. I was just teasing a co-worker who was a size 1 for the last 20 years and is now about a 14. I could not believe her skin could stretch so far.

[Bojax39]

"I was just teasing a co-worker who was a size 1 for the last 20 years and is now about a 14. I could not believe her skin could stretch so far."

Why how NICE of you. I'll bet she couldn't believe your mean spirited snottiness could stretch so far.

Be sure to tell her if you get some wasting illness. That way she can make taunting little comments on your dramatic weight loss. :-)

[ethelouise]

What is not discussed here is that smoking controls blood sugar and once you stop blood sugar elevates and here comes the uncontrollable weight gain, as much as 50 pounds. They keep saying it goes away but that's a lie. Screwing with brain chemistry does not control weight.

[Mondia77006]

I think these stories are planted by the tobacco companies. The most laughable was one where a Dr told a patient he would rather have him smoke than quit 4 wks before surgery, because quitting "causes phlegm". Enough of these stupid stories that say cigarettes and alcohol are either good for you, or harmful to quit.

[steveherb1]

Greed causes stress. Stress leads to depression. If we lived in a land where it wasn't all about the money, we wouldn't have the stress; therefore we wouldn't have the depression. Utopia? Nah. I want a new drug.

[sarahgordon185]

This is a terrible, misleading, false headline which contributes to people refusing to attempt smoking cessation. Most people do not "get fat" from quitting. The studies show about a 5-pound gain. How many people looked at this headline and had their false idea of tremendous weight gain reinforced and supported their refusal to stop smoking? Very irresponsible of you. Read the studies.

[mjb89]

Having been there, done that, I gained about 25 pounds after I quit smoking.

[muchiebella]

I quit smoking a couple years ago with chanix it worked great ,I didn't eat more than I did when I was smoking ,I gained 45 lbs. in two months! and I have lower back issues so I started smoking again and I lost the 45 lbs and then some. sometimes experience is the study !