How did the tobacco ban increase inmates’ body weight during incarceration in Canadian federal penitentiaries? A cohort study

OBJECTIVE: This study aimed to determine how inmates’ body weight changed during incarceration in Canadian federal penitentiaries, based on their history of tobacco use. Since tobacco was banned from all Canadian federal penitentiaries in 2008, little is known about the unintended health consequences of this ban, especially on inmates’ body weight. DESIGN: Cohort study. SETTING: Participants were male and female inmates incarcerated for at least 6 months in Canadian federal penitentiaries. We collected data from 10 institutions in two Canadian regions (Ontario and Atlantic). PARTICIPANTS: We collected data from 754 inmates who volunteered to participate in the study. INTERVENTION: This study examined weight change in relation to a history of tobacco use. In 2016–2017, anthropometric data were collected and compared with recorded anthropometric data at the beginning of incarceration (mean follow-up of 5.0±8.3 years). Self-reported data on tobacco and substance use were collected. Weight change was compared between inmates with and without a history of tobacco use. OUTCOMES: The main outcome measures were body weight change (kg), body mass index (BMI) change (kg/m(2)), annual weight change (kg/year), and BMI and waist circumference (cm) at the time of the interview. RESULTS: During incarceration, ex-smokers gained more than twice the amount of weight compared with non-smokers (7.5 kg weight gain for smokers vs 3.7 kg weight gain for non-smokers). Once adjusted for covariates in a regression analysis, for inmates who gained the most weight (75th and 90th percentiles), non-smokers had, respectively, 1.64 and 2.3 lower BMI points than ex-smokers. CONCLUSIONS: During incarceration in Canadian federal penitentiaries, inmates with a history of tobacco use gained significantly more weight than non-smokers. This put them at increased risk of developing obesity-related health problems. This information is important for the prison setting when planning related programmes and regulation.