Most people who stop smoking gain weight, and most of it arrives in the first few months. That's the summary from a 2021 Cochrane review of the research on preventing it. A meta-analysis published in 2012 estimated an average gain of about 4.7 kg across the first year, most of it in the first three months, with substantial variation between people.
Two things are worth knowing before the detail. The spread around that average is enormous — a sixth of people lose weight instead. And the weight gain does not appear to cancel out the health benefit of quitting, which is the part most people assume it does.
The honest numbers
The most thorough figures come from that 2012 meta-analysis of 62 studies, following people who quit without any treatment aimed at their weight. These are averages across those studies, not a forecast for one person:
- 1 month: about 1.1 kg
- 3 months: about 2.9 kg
- 6 months: about 4.2 kg
- 12 months: about 4.7 kg
The curve flattens. Most of the gain has happened by the three-month mark, and the second half of the year adds about half a kilo.
Averages hide the useful part, though. At twelve months, that same analysis found 16% of people had lost weight, 37% gained less than 5 kg, 34% gained 5–10 kg, and 13% gained more than 10 kg.
So "you'll put on five kilos" isn't really what the evidence says. It says the middle of a very wide distribution is around five kilos, and which part of that distribution you land in isn't something anyone can tell you in advance.
One caveat on those figures, stated plainly: that analysis was published in 2012, which is older than the sources we normally use. We've kept it because nothing more recent maps the month-by-month curve as carefully, and the direction is consistent with newer work.
Where the weight comes from
Increased appetite and hunger are on the US National Cancer Institute's list of nicotine withdrawal symptoms, and how long they last varies a lot between people. That's the part you'll actually notice: food is more interesting than it was, and the hand that used to reach for a cigarette after dinner has nothing to do.
We're not going to walk you through a metabolic explanation, because the full picture is less settled than the internet suggests. The pattern is well documented. The mechanism is less tidy.
Does the weight cancel out the benefit?
This is the question underneath the question, and it has a reasonably clear answer: no.
A 2021 study in JAMA Network Open followed 16,663 Australian adults for eight years. People who quit gained an average of 3.14 kg more than those who kept smoking. Their risk of death was still substantially lower than the continuing smokers' — and that held across every weight-change group reported, including those who gained more than 10 kg. In that cohort, neither weight change nor BMI change after quitting was linked to a higher risk of cardiovascular disease, type 2 diabetes, cancer or COPD.
That's one population, and it doesn't settle the question everywhere. Earlier research has reported possible short-term increases in type 2 diabetes risk after quitting, particularly among people who gain a lot of weight.
A meta-analysis the same year, pooling nine studies, found the same direction for heart disease. People who quit had lower cardiovascular risk than continuing smokers whether they gained weight or not.
Both of those are observational studies, which means they show a consistent pattern rather than proving cause. The safe reading is the modest one: gaining weight after quitting did not remove the benefit of having quit.
What the evidence says about preventing it
Here the news is more mixed, and the Cochrane review is blunt about it: there is no intervention for which there is moderate certainty of a clinically useful effect on long-term weight gain.
What it did find:
- Exercise programmes may reduce weight gain at twelve months, on low-certainty evidence from three studies covering 182 people. During the programme itself the effect was minimal.
- Personalised weight management — real assessment, planning and feedback — may reduce weight gain by the end of treatment, on very low-certainty evidence. At twelve months the review found no evidence of a lasting effect.
- Generic weight programmes, without that personalisation, didn't reduce weight gain and may have reduced quit rates. Low to very low certainty, and the finding worth being careful about: a diet plan bolted onto a quit attempt can work against the quit.
- Nicotine replacement probably reduces weight slightly, by around a third of a kilo, with a similar effect at twelve months. Moderate certainty, small effect.
- Varenicline made very little difference by the end of treatment, on high-certainty evidence. Bupropion limited weight gain during treatment on low-certainty evidence, with no benefit left at a year.
- Acceptance-based programmes, which work on how you relate to the urge rather than trying to control it, increased quit rates at six months while making little difference to weight. At twelve months the review found no evidence either way.
Read together, the approach carrying least risk is the one that doesn't put the quit itself in danger. The evidence doesn't crown a single method that suits everyone.
If "smoking keeps me thin" is the reason you haven't quit
Then it's worth naming that as a belief and testing it, rather than carrying it unexamined.
It's a borrowed one, and it usually arrives culturally — from films, from fashion, from an older cousin who said it once with enough confidence that it stuck. It's not baseless. Appetite really does change. But the belief being sold to you is that smoking is a weight-management strategy. It isn't a safe or sensible one, and what the evidence actually supports is smaller: that quitting is followed by a gain of a few kilos for most people, which doesn't take the health benefit with it.
That's our reading of it, not a finding of the research. It's also the kind of belief the nine borrowed beliefs post goes through one at a time.
Where Nicoxit comes in
We don't put you on a diet while you're quitting. The Cochrane finding above is one reason. A generic weight programme bolted onto a quit attempt can cost you the attempt, so we don't run one.
What you get instead is 31 modules, about 40 minutes a day, over seven days — a course, not a tracker, grounded in MBCT, ACT and implementation intentions, which is where the belief work comes from. You keep smoking during the programme while you do it.
And your progress, without the streak that punishes you for slipping. Days free, money saved, health-recovery milestones. If the number on the scale moves in the first three months, nothing in the app treats that as a failure, because the evidence doesn't.
Day 1 is free — modules 1 to 3, if you want to see how the course handles this before committing.
The position this post defends
Weight gain after quitting is real, averages a few kilos, mostly happens early, and varies so much between people that the average is nearly useless as a personal forecast. What the evidence does not support is treating it as a reason to keep smoking.
Wondering which belief is doing the most work for you? Take the 3-minute Quit Profile quiz — a reflection tool, not a clinical assessment.
Related reading:
- Nicotine Withdrawal Symptoms: What's Normal, and What to Expect
- What Happens When You Quit Smoking — Hour by Hour
- 9 Borrowed Beliefs Every Smoker Carries
- Do Nicotine Patches Actually Work? What the Evidence Says
References
- Hartmann-Boyce, J., Theodoulou, A., Farley, A., Hajek, P., Lycett, D., Jones, L. L., Kudlek, L., Heath, L., Hajizadeh, A., Schenkels, M., & Aveyard, P. (2021). Interventions for preventing weight gain after smoking cessation. Cochrane Database of Systematic Reviews, 10, CD006219. https://doi.org/10.1002/14651858.CD006219.pub4
- Sahle, B. W., Chen, W., Rawal, L. B., & Renzaho, A. M. N. (2021). Weight gain after smoking cessation and risk of major chronic diseases and mortality. JAMA Network Open, 4(4), e217044. https://doi.org/10.1001/jamanetworkopen.2021.7044
- Wang, X., Qin, L.-Q., Arafa, A., Eshak, E. S., Hu, Y., & Dong, J.-Y. (2021). Smoking cessation, weight gain, cardiovascular risk, and all-cause mortality: a meta-analysis. Nicotine & Tobacco Research, 23(12), 1987–1994. https://doi.org/10.1093/ntr/ntab076
- Aubin, H.-J., Farley, A., Lycett, D., Lahmek, P., & Aveyard, P. (2012). Weight gain in smokers after quitting cigarettes: meta-analysis. BMJ, 345, e4439. https://doi.org/10.1136/bmj.e4439
- National Cancer Institute. Handling Nicotine Withdrawal and Triggers When You Decide to Quit Tobacco. https://www.cancer.gov/about-cancer/causes-prevention/risk/tobacco/withdrawal-fact-sheet
Frequently asked questions
How much weight do you gain after quitting smoking?
On average, somewhere between four and five kilos in the first twelve months, with most of it in the first three months. The spread is wide: at one year, about 16% of people had lost weight, 37% had gained under 5 kg, 34% gained 5–10 kg, and 13% gained more than 10 kg.
Is weight gain after quitting smoking temporary?
The gain slows down — most of it in the first three months, with the rest of the first year adding much less. Whether it comes back off later isn't something the evidence establishes, and longer-term data is limited. Weight trajectories differ a lot between people.
Does gaining weight cancel out the benefit of quitting?
No, on the evidence available. An eight-year Australian study of over 16,000 people found the lower risk of death among people who quit held at every level of weight gain, and in that cohort found no link between weight change after quitting and cardiovascular disease, type 2 diabetes, cancer or COPD. A 2021 meta-analysis found lower heart-disease risk among quitters whether or not they gained weight. Both are observational, so they show associations rather than proof of cause.
Should I diet while I'm quitting?
Be careful with this one. The Cochrane review found that weight programmes without personalised assessment, planning and feedback didn't reduce weight gain and may have reduced quit rates, on low to very low certainty evidence. Personalised support may reduce weight gain, though the evidence there is weaker again. If weight is a real concern for you, it's worth raising with a qualified professional rather than bolting a generic plan onto the quit.
Will nicotine gum or patches stop me gaining weight?
Only slightly. Nicotine replacement probably reduces weight gain by about a third of a kilo at twelve months. That's a real effect, and a small one. What patches do and don't do covers the rest.
Does exercise help?
It may. Exercise programmes reduced weight gain at twelve months in the trials the Cochrane review pooled, on low-certainty evidence from three studies covering 182 people, and the effect during the programme itself was minimal. Exercise has other benefits; its specific effect on post-quit weight remains uncertain.