The Truth About Smoking and Weight Loss

Smoking is the leading cause of preventable disease and death—killing aboutone in five peopleeach year in the United States, according to the Centers for Disease Control and Prevention (CDC). Luckily, when someone quits smoking, it reduces their risk of developing serious health conditions, such as cancer and cardiovascular disease. Quit before age 40 and your risk of dying from smoking-related illness drops by about 90 percent.

Quitting can be difficult. And if you’re a smoker who wants to quit, you might be concerned you’ll lose the pack but pack on the pounds. There is a lot of information about the link between smoking and weight control—much of it is mythical. Here are the worries that may stop you from quitting and what you should know.

Reality:On average, smokers weigh less than never smokers. Former smokers weigh more than current smokers. But that’s not the complete picture.

“All smokers are not skinny,” saysKaren Johnson, MD,endowed professor of women’s health at the University of Tennessee Health Science Center’s department of preventive medicine. “The myth that cigarette smoking keeps you thin is incorrect.”

Heavy smokers tend to weigh more than light smokers, according to 2018studyby the International Agency for Cancer Research. The study of 450,000 UK participants found people genetically predisposed to obesity may be at a higher risk of taking up smoking, and of smoking more.

It also doesn’t mean the more you smoke, the slimmer you’ll look. In fact, it may change your shape in ways you don’t expect. An increase in cigarettes smoked per day was associated with a larger waist circumference and more abdominal fat, according to astudyof more than 6,000 Swiss men and women. In addition, a later meta-analysis published in a 2015British Medical Journalissue analyzed the genetic information of nearly 150,000 current, former, and never smokers and found for a given BMI, a gene variant associated with heavy smoking may lead to a relative increase in waist circumference. Translation: It’s not conclusive, but the more you smoke, the more you could end up carrying weight around your middle.

Reality:Most smokers gain do weight when they quit, but the amount is less than you might think. And one in four quitters don’t gain any weight, saysAlicia Allen, PhD, MPH, assistant professor of family and community medicine at the University of Arizona School of Medicine, who studies substance abuse disorders.

Australian researchers sought to quantify the difference of weight gain between quitters and continual smokers overtime. In ameta-analysisof 35 worldwide studies, including 63,403 quitters and 388,432 continuing smokers over a five-year period, they reported that both gain weight. They found that quitters gained an average of 2.6 kilograms, or 5.7 pounds, more than people who continued to smoke.. Heavy smokers gained the most weight.

“Both people who smoke and quit gain weight over time. It’s just what happens to the population as we age,” saysSeana Gall, PhD, senior research fellow in cardiovascular epidemiology at the Menzies Research Institute in Tasmania, Australia, and current chair of the Tasmanian Government’s Tobacco Control Coalition. “The important thing to stress is the amount in weight gain is very small between those who quit smoking versus those who continue to smoke.”

The bottom line:Studiesthat look at quitting smoking and weight gain have found about 16 percent of quitters actually lost weight, while 13 percent gained more than 10 kilograms, or more than 22 pounds. Most of the weight gained occurred within the first three months of quitting.

Reality:The debate continues. Some studies say men gain more weight when they quit, others say women do, says Gall. Her 2015 meta-analysis wasn’t a true tie-breaker. “We did find that women gained slightly more than men, but it wasn’t statistically significant,” she says.

While sex doesn’t play a crucial role in weight loss, it does when it comes to quitting. Women are much more concerned than men about gaining weight and that affects whether they’ll stick with efforts to quit smoking, says Johnson.

Asurvey of smokersfound 75 percent of women, versus 35 percent of men, said they were unwilling to gain more than 5 pounds (2.3 kg) in order to quit smoking. Women’s uppermost threshold was 5.8 pounds, or 2.6 kg—in line with the average weight gain found in Gall’s meta-analysis. Five pounds was also the don’t-pass-go number in a laterstudyof women smokers.

Reality:When it comes to smoking and weight loss, metabolism—how your body processes food for energy, often gets the credit for weight control. Smoking does increase your metabolic rate, but only slightly.

A 2016 review of literature about thelittle-understood effects of smoking cessationon metabolic function finds it’s more much more complicated: Smoking plays various roles, both physiologically and behaviorally, in suppressing appetite and keeping weight down.

“Because you’re smoking, you might eat less because you’re occupying your hands and mouth with other things. That’s the behavioral aspect,” says Allen. Physiologically, the release of chemical compounds in the brain, such as dopamine and norepinephrine, may play a role in how the body desires food and how much we eat, she says.

Reality:When it comes to weight loss, it doesn’t matter whether you never smoked, currently smoke, or are an ex-smoker, says Johnson, who studies weight loss interventions. How you try to lose the weight is what matters.

In a May 2018study, Johnson and other researchers analyzed data on 4,387 people with type 2 diabetes who hadoverweight or obesity, by smoking status, participating in studies comparing weight loss between intensive lifestyle intervention and diabetes support and education (DSE). There was no difference in weight loss among the three groups—never, current, or ex-smokers. But there was a huge difference between weight loss programs: All participants lost the most weight—dropping 8.8 percent of their body weight on average over one year—with intensive lifestyle interventions. DSE resulted in only a 0.7 percent reduction in body weight.

“We’ve done some research to try to help people stop smoking without gaining weight and we’ve been able to reduce the amount of weight they do gain by getting them to watch what they eat and being more physically active,” says Johnson. “It makes a big difference in how much weight you gain.”

Reality:Obesity increases your risk of type 2 diabetes, which is a risk factor for heart disease. But, while you might think you’re better off smoking to keep obesity at bay, the opposite is true.

Smoking and nicotine—the addictive substance in tobacco, can increase insulin resistance which increases your risk of type 2 diabetes. “The most important thing you can do to minimize your risk of diabetes is to stop smoking,” saysSteve Schroeder, MD,professor of medicine at University of California, San Francisco. “And if you don’t gain weight you’ll have even less risk of getting diabetes once you quit smoking.”

Researchers have been studying whether weight gain after quitting smoking leads to worse health outcomes related to diabetes and cardiovascular disease.Researchfinds that health risks of smoking far outweigh the slim chance of developing diabetes that comes with weight gain from quitting.One recent Harvard reviewfound substantial weight gain post-smoking cessation increased the short-term risk of type 2 diabetes, but it didn’t outweigh the health benefits of quitting smoking on cardiovascular disease and all-cause mortality. So even if you might be heavier after you quit smoking, but you’ll behealthier, since you have diminished the cardiovascular risks associated with smoking.

If you already have diabetes, quitting smoking is even more important. “Half of all smokers with diabetes will die from smoking-related illness,” says Schroeder. “If you don’t smoke, maintain your weight, and keep your lipids and triglycerides in check, you can have diabetes and live a long healthy life.”

Reality:It’s long been thought that a smoker’s sense of smell and taste—or lack thereof—may play a part in appetite suppression. In a 2018 systematic review of literature researchers founda link between tobacco and problems with smell and taste, but how that influences eating behaviors in smokers and those trying to quit is still unknown.

“Most of your ability to enjoy food is related to your sense of smell. Cigarettes really knock that out,” says Johnson. “That probably plays into part of the weight gain (when you quit smoking). They are suddenly able to taste food better than when they were smoking.” Better tasting food could mean that you start eating more.

Additionally, some research models suggest thatsmokers may crave sugary foods when they quit. Does this mean you be tempted to replace your smoking habit with a candy bar habit? Not necessarily.

Getting accurate measures of what people eat is actually a difficult thing to study, says Gall, who has tried to examine whether diet plays a role in quitting smoking and weight gain. Herstudyof 281 Australians age 26 to 36 surprised her. Different dietary behaviors didn’t explain why people gained weight after quitting, she says.

“People who quit smoking actually tended to improve their diet,” says Gall. “They were eating more healthy foods than unhealthy foods, but that wasn’t enough to counteract the other effects causing weight gain.”