Abstract Background The indirect effects of the COVID-19 pandemic on healthy living behaviours are multiple and complex to assess. The aim of the study is to assess the impact of the COVID-19 pandemic in Italy on: smoking, alcohol, fruit and vegetable consumption, and sedentary lifestyle, through the Italian Behavioral Risk Factor Surveillance System (PASSI) data. Methods PASSI 2008-2022 data refer to a sample of 497,223 18-69-year-olds residing in Italy. For each behaviour, from the monthly prevalence data, the 2008-2022 time series was estimated with LOWESS regression and an interrupted time series (ITS) analysis was conducted, using the generalized least squares (gls) model, taking into account autocorrelation (ARMA matrix) and considering March 2020 (start of WHO-declared pandemic) as the month of ‘interruption’ of the series, to show the difference between what was observed and what was expected under the assumption that the pandemic had not happened (‘counterfactual’ scenario). Results In December 2022 the share of people who consume at least 5 servings of fruits and vegetables per day is lower than the counterfactual scenario (6.7% vs 9.1%), while the share of higher-risk alcohol users is significantly higher (19.5% vs 16.9%). In contrast, the share of sedentary people (according to WHO guidelines) is significantly lower than the counterfactual (27.9% vs 31.8%). The pandemic does not seem to have had a significant impact on smoking. Conclusions These results show a worsening impact of the pandemic on alcohol consumption and fruit and vegetable consumption. Sedentariness shows better data at the end of 2022 and smoking remains mostly unchanged. It will be necessary to continue monitoring the impact of the pandemic over longer periods to confirm the findings. Key messages • Understanding changes in lifestyle indicators is critical to design ad hoc interventions to reduce the burden of noncommunicable diseases, and especially during health emergencies such as pandemics. • Through this work it is possible to clearly observe how the pandemic has impacted lifestyle habits.