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expert reaction to research into the potential of e-cigarettes to combat obesity

In line with the effects of smoking on appetite suppression the impact of e-cigarettes with nicotine and flavouring on appetite and weight control is explored in a paper published in the journal Nicotine & Tobacco Research with the authors suggesting areas of further study.


Prof. Theresa Marteau FMedSci, Director of the Behaviour and Health Research Unit at the University of Cambridge, said:

“The appetite suppressing effects of nicotine are well known, as implied some decades ago in an advert for a popular American brand of cigarettes: ‘Reach for a Lucky instead of a Sweet’.

“The commentary from Glover and colleagues outlines some plausible reasons why vaping with food-flavoured e-liquids might help ex-smokers avoid weight gain. This is an idea echoed in the marketing of a brand of milk chocolate flavoured e-liquids described as having 50 servings and no calories.

“Vaping could be ‘The New Weapon in the Battle of the Bulge’ and the many dangers of obesity mean it’s worth examining, but we must also make sure that e-cigarettes don’t become a kind of snake oil, distracting ex-smokers from other established and effective weight loss interventions. Also of concern is the attraction of non-smoking girls and young women to food-flavoured e-cigarettes in the hope of weight control. E-cigarettes might have potential to reduce obesity in some, but they are not a panacea for the population and we will need much more detailed research to know if they can ever be used effectively and safely.

“In the absence of direct evidence about the impact on weight of vaping with food-flavoured e-liquids, caution is warranted over any suggestions of their weight loss properties. Studies are now needed to assess their potential for harm as well as good.”


Prof. Susan Jebb, Professor of Diet and Population Health at the University of Oxford, said:

“Many people who quit smoking gain weight with an average increase of 4.7 kg in the first 12 months of abstinence, and nearly 1 in 8 people gain more than 10kg. Fear of weight gain may prevent some people from giving up smoking, even though the health benefits would be considerable and, for the vast majority of people, outweigh the risks of weight gain.

“Weight gain following smoking cessation occurs for three main reasons. First, nicotine has a mild stimulant effect on metabolic rate, so energy expenditure declines after quitting smoking. Second, nicotine activates neural pathways that reduce appetite. Third, many people replace smoking with snacking, often on high energy foods. For these reasons, this article makes a plausible case that quitting with e-cigarettes which contain nicotine, especially those with sweet or food-related flavours, may reduce the risk of weight gain. But to date there have been no clinical trials to test this idea.

“But it is important not to confuse this possible strategy for the prevention of weight gain among people who are trying to quit smoking with strategies for non-smokers who are trying to lose weight. There is no evidence that e-cigarettes would be helpful for weight loss, a process which requires far greater control over food intake than the prevention of weight gain.  As the authors themselves caution, it would not be advisable for non-smokers to start using nicotine, given its highly addictive properties, or to expose themselves to the potential long-term risks of vaping.

“In summary, e-cigarettes are an effective strategy to help people stop smoking and improve their health. If they also help smokers who quit to limit weight gain that would be a bonus, though not yet proven. But e-cigarettes are not harmless and there is no evidence they aid weight loss, so are not recommended for non-smokers.”


Prof. Peter Hajek, Director of the Tobacco Dependence Research Unit at Queen Mary University of London, said:

“Nicotine may have a potential in weight management, but given the serious risks of smoking, this aspect has rightly never attracted much attention. The effect also has a negative side to it – it is responsible for the weight gain smokers can experience when they quit. E-cigarettes could be of help here in that smokers who switch to vaping are likely to avoid at least some of the problem – as well as most of the risks of smoking. More evidence is needed in this area, but if this new publication encourages more smokers to switch to vaping, it will be a good thing.”


Prof. Paul Aveyard, Professor of Behavioural Medicine at the University of Oxford, said:

“On average, people who stop smoking gain around 4-5kg in a year and around 6-7kg (one stone) more in the long-term than they would have gained if they had continued smoking. However, some people gain no weight at all or lose weight, while others gain much more than this. This weight gain is partly muscle, but it is partly unhealthy fat tissue that can damage health. Even in people who start at a healthy weight, putting on extra fat increases the risk to health, increasing the risk of mortality by around 12% and increasing the risk of diabetes also.That said, the risks of gaining weight are much lower than the risks of continuing to smoke, even for people who do gain a lot of weight.

“The evidence is very clear that nicotine consumption after stopping smoking suppresses weight gain. In the studies to date, nicotine has been taken as nicotine replacement treatment rather than e-cigarettes but, as e-cigarettes deliver nicotine at the same or higher doses than NRT, we can expect the same effect from e-cigarettes. Trials show nicotine reduces weight gain by 0.5kg in the short-term. Studies of people who continue using nicotine long-term suggest a few kilos difference.

“There are other good reasons to investigate this further. When people with diabetes stop smoking their blood sugar control worsens for a year or two. People who stop smoking have a higher risk of developing diabetes in the few years after they stop than people who continue smoking, although only a small number of people who stop smoking develop diabetes. If we could prevent these problems, we should, and e-cigarettes are worth considering. The authors also raise the possibility that the taste effects may suppress appetite, a feature of cigarettes not shared by NRT, but whether this is important or not is unknown.

“If e-cigarettes reduce the risk of weight gain, they will reduce the risk of developing diabetes, but there are reasons to be cautious. Smoking itself partly causes diabetes. When people stop smoking, their risk of developing diabetes is lower than that of continuing smokers once they have been stopped for a few years. Smoking causes insulin resistance, which is an important role in causing type 2 (adult-onset) diabetes and at least some of this effect may be due to nicotine. Thus e-cigarettes may have competing actions and the balance of benefits and risks is unknown.  As a consequence, what this paper rightly does is put forward proposals for research to examine the balance of risks and the benefits.

“The evidence overall is that e-cigarettes have benefited public health in the UK. They appear to have helped people stop smoking and the concerns about non-smokers becoming chronic users are so far unfounded. Should people who stop smoking continue using e-cigarettes long-term to prevent weight gain and benefit their health? People who fear they would relapse to smoking without an e-cigarette should undoubtedly continue.  Any discussion about the benefits and harms from continued use of e-cigarettes on the risks of weight gain and diabetes pale beside the major risk posed by smoking.

“People who feel they could stop e-cigarettes and not return to smoking have a choice. While there are strong reasons to think it will prevent some weight gain in people who stop smoking, there is not enough evidence to confidently recommend people use e-cigarettes for this reason alone. In people who have never smoked, the risks are likely to outweigh any benefits- there is simply no evidence that regular nicotine consumption reduces weight in people who have not smoked.”


‘Could Vaping be a New Weapon in the Battle of the Bulge?’ by Marewa Glover et al. will be published in  on Tuesday 25 October 2016. 


Declared interests

Prof. Hajek received researcher funding from and provided consultancy to manufacturers of stop-smoking medications. He has no links with any e-cigarette manufacturers. His research into e-cigarette safety and effects has been funded by NIHR, PHE, UKCTAS and MHRA.

Prof. Aveyard: I am employed by the University of Oxford and the NHS.  I receive grant funding from the NIHR and MRC and Cambridge Weight Plan, a private company that provides very low energy diets and behavioural support to help people lose weight.  I am Senior editor of Addiction, Editor of Cochrane Tobacco Addiction Review Group, both voluntary positions.  I am chair of Cancer Research UK’s Tobacco Advisory Group.  I receive no personal funding from any private or profit-making concern.  In one trial, Glaxo Smith Kline have donated nicotine replacement to the NHS in support of the trial.  In others, Slimming World, Rosemary Conley and Weight Watchers have donated free behavioural support programmes to the NHS in support of the trial.  These donations do not benefit me or my employers directly.

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