How much weight people gain after quitting smoking

Worry about weight keeps some people from trying to quit, so the actual size of the gain is worth knowing. The most detailed analysis comes from a 2012 meta-analysis in the BMJ by Henri-Jean Aubin and colleagues, which pooled 62 studies of people who stopped smoking and tracked their weight for up to 12 months. For people who quit without any treatment, the average gain was 4.67 kg at 12 months (95% confidence interval 3.96 to 5.38). That average hides a large spread: some people lost weight and some gained a good deal more. This page covers the numbers, why weight tends to rise, why health bodies say quitting still comes out ahead, and how they suggest managing it.

What the BMJ meta-analysis found

The authors searched trials of quit-smoking treatments and exercise that reported weight change in people who stayed off cigarettes. They calculated average weight change from the start of the quit attempt at one, two, three, six and 12 months. For people who quit without drugs or other treatment, the means were as follows.

The authors conclude that quitting is associated with a mean increase of 4 to 5 kg after 12 months of abstinence and that most of the gain happens within three months of quitting. They also found estimates of weight gain were similar for people using different medicines to support quitting, and similar between people who were especially concerned about weight gain and people who were not.

The average hides a wide range

From the means and standard deviations, the authors calculated that at 12 months, 16% of untreated quitters had lost weight, 37% had gained less than 5 kg, 34% had gained 5 to 10 kg, and 13% had gained more than 10 kg. The experience of quitting differs a lot between people.

The authors make a few other points worth knowing. Their figure is higher than the 2.9 kg that earlier leaflets often quoted, which came from an older review whose methods the authors criticise for combining estimates in ways that could be inaccurate. They also note that average adult weight tends to creep up over a year anyway, and estimate that roughly 4.3 kg of the average 12-month gain in their analysis was due to quitting itself. Finally, the data cover only people who stayed off cigarettes for up to a year. For those who gain weight and then go back to smoking, available data suggest weight falls again, and what happens beyond the first year is unclear, since evidence on continuing gain is conflicting.

Other sources frame it more loosely. The NCI says the weight gain after quitting is usually less than 10 pounds. That wording uses different units and a looser definition of "usually" than the BMJ analysis, so the two should not be compared number for number.

Why weight rises after quitting

The BMJ authors say smoking cessation probably causes weight gain because nicotine in cigarettes is an appetite suppressant, and they note that increased appetite is one of the most common and longest lasting symptoms of tobacco withdrawal. They add that evidence suggests nicotine raises the basal metabolic rate, meaning the energy the body burns at rest, so removing nicotine can lower energy expenditure just when appetite is higher. Smokefree.gov makes the same points in plain language: smoking cigarettes makes you feel less hungry, and it increases metabolism so you burn more calories.

Behaviour plays a part as well. The CDC says it is normal for appetite to increase some when you quit, that your body may not burn calories quite as fast, that you may eat more because of the stress of quitting or to have something to do with your hands and mouth, and that food may taste better because smoke is no longer dulling your senses of smell and taste. Smokefree.gov adds that eating can become a substitute for smoking. For where hunger fits among the other early symptoms, see the withdrawal symptoms and timeline page.

Why the health case for quitting still stands

The NCI states that the health benefits of quitting far outweigh the health risks of a small amount of extra weight, and adds that fear of gaining weight should not discourage anyone from quitting. Smokefree.gov says that while many smokers gain some weight, it is better for your health if you quit as soon as possible, and that quitting adds years to your life and reduces the risk of serious diseases. The BMJ authors do acknowledge a real caveat: some people may gain enough to raise their risk of diabetes, among other complications, and they suggest doctors could spot people gaining excessive weight and step in early.

The wider benefits of stopping are laid out on what happens to the body after you quit. Weight gain is one side effect to plan around, not a reason to stay with smoking.

What public bodies suggest for managing it

The advice is consistent across the CDC, NCI and Smokefree.gov and centres on ordinary habits:

• Plan healthy snacks, such as celery, carrots or sugar-free mints, that keep hands and mouth busy (CDC).
• Pay attention to portions and drink enough water, since thirst can feel like hunger (Smokefree.gov).
• Be physically active; Smokefree.gov says just 10 minutes of exercise a day can make a difference, and the CDC says any activity is better than none.
• Eat without distractions and more slowly, so you notice fullness (CDC and Smokefree.gov).
• Find ways other than eating to cope with stress and emotions (Smokefree.gov).

The NCI also reports that studies show nicotine replacement products, especially nicotine gum and lozenges, can help counteract weight gain, and that the medicine bupropion has been shown to help as well. Those options are explained on the pages for nicotine replacement therapy and prescription medicines for quitting, and the choice belongs with a doctor or pharmacist. The NCI adds that a nutritionist or diet counsellor can be helpful. Planning for appetite before the quit date is part of preparing to quit.

People with diabetes, an eating disorder, heart disease or a mental health condition, people who are pregnant, and anyone taking other medicines should raise weight and appetite changes with a clinician rather than manage them alone.

The short version

On average, people who quit without treatment gained 4.67 kg over 12 months in the BMJ analysis, mostly in the first three months, with a wide range from weight loss to more than 10 kg. Nicotine's effect on appetite and metabolism explains much of it, and public health bodies say the benefits of quitting outweigh a modest gain. A doctor or pharmacist can help with appetite, medicines and weight, especially for people with diabetes, heart disease, an eating disorder or a mental health condition, or those who are pregnant.