Effect of E-Cigarette Substitution for Cigarettes on Weight Status: A Systematic Review

BACKGROUND: The substitution of smoking with electronic nicotine delivery systems (ENDS) is increasingly used as a strategy for tobacco cessation or reduction, and its impact on body weight is a key area of research. AIMS: To examine the effects of ENDS on weight status in adults who smoke cigarettes. METHODS: A comprehensive search was conducted in Scopus, PubMed, and the Cochrane Library from 2010-February 2024. Studies were included if they were randomized or non-randomized controlled trials, prospective or retrospective cohort studies reporting longitudinal body weight measurements of adults who smoked cigarettes and either partially or entirely substituted ENDS for smoking. Quality assessment was performed using the JBI quality assessment tools, and bias was reported using the Oxford Catalogue of Bias. The GRADE approach was used to evaluate the certainty of the evidence. RESULTS: The systematic review included nine articles from eight trials. Study designs were five RCTs, two cohort studies, and one quasi-experimental study. Two studies had a high risk of bias, five had some concerns, and one was at low risk. Weight change varied, with a consistent pattern of weight gain over time for exclusive ENDS users and modest weight gain for dual users. The overall body of evidence was considered weak because the total number of participants was less than 1000. CONCLUSIONS: ENDS use may have a modest impact on weight status among individuals trying to quit smoking. However, the evidence base is limited, and further research is needed to understand the long-term effects of ENDS use on weight.