Introduction

Smoking, whether permitted or not, is a major part of the prison culture, mainly because so many inmates identify as smokers. In Canada, smoking rates among inmates, prior to incarceration, are estimated to be between 50% and 93%.1–7 Those rates are four to five times the smoking rate of the general Canadian population,5 estimated to be between 13% and 17%.8–10 The primary reason why smoking rates are so high among prisoners is because many of them suffer from conditions that correlate with high tobacco use, including substance misuse, psychiatric disorders, poor impulse control and low socioeconomic backgrounds.11 12 Traditionally, before the tobacco ban in Canadian federal penitentiaries, the high rates of smoking meant inmates and staff were exposed to unusually high amounts of secondhand smoke.13 We know from studies on tobacco control in prison that total tobacco bans have reached their goal of reducing harmful exposure to secondhand smoke and subsequently reducing related ailments.14 In 2008, Canada proactively took the lead and adopted a total tobacco ban for all 41 federal correctional institutions.15 This means of the 14 000 inmates incarcerated in federal penitentiaries across Canada, approximately 10 000 were forced to quit smoking on admission to the penitentiary (or quit smoking when the ban occurred in 2008).16 Although the tobacco ban is considered a good public health measure in several aspects (eg, improving air quality), there is a lack of research on the unintended consequences of tobacco bans in prisons.17–19 It is relevant to examine these unintended consequences because many prisons are now implementing tobacco control policies (from partial indoor bans to completely prohibiting tobacco) worldwide.7 20–22 Our findings on weight gain as an unintended consequence of a total tobacco ban could influence decision makers on their choice of tobacco control regulation and the support provided to inmates withdrawing from tobacco during incarceration.

Generally, studies on obesity in prison found obesity prevalence in male inmates to be similar or lower than the general population.23–25 However, many of the studies were self-reported, cross-sectional and did not assess change in weight during incarceration. Of the studies that did assess weight gain in prison, findings revealed that 50%–80% of inmates gained weight during incarceration.26 Moreover, there appears to be important variability in weight gain, ranging from a modest 0.96 kg over 2 years27 to a substantial 0.5 kg gain per week.28 When inmates gained substantial amounts of weight, authors often speculated it is because of withdrawal from tobacco, alcohol or drugs.28 29 However, they lack data to back up these claims, since there are few data on the factors that contribute to weight gain during incarceration.24 An American study demonstrated that female prisoners who participated in a voluntary smoking cessation programme (that included transdermal nicotine replacement) while incarcerated gained more weight at the 6-month postcessation follow-up compared with inmates who continued to smoke (on average 4.5 kg more than smokers).30

The majority of studies on obesity in prison were out of Australia, the USA and the UK.26 In our recent publication, we found that Canadian inmates gained a significant amount of weight during incarceration.25 Our findings showed that, on admission, obesity rates were similar to the general Canadian population (~27%), but after at least 6 months of incarceration obesity rates increased to 45% for the inmate population.25 We suspect the observed weight gain was associated with tobacco cessation in Canadian inmates.

To fill this knowledge gap, this study examined, for the first time, how inmates’ body weight changed in Canadian federal penitentiaries during incarceration based on a history of tobacco use prior to incarceration. Our aim was to gain insight on the factors related to inmate weight gain by drawing a comparison between the weight gained (from admission to follow-up) in inmates who were in withdrawal from tobacco, or other substances (drugs and/or alcohol), and inmates not battling addictions during incarceration. Because smoking cessation is known to be associated with weight gain,31 32 we hypothesised that inmates with a history of tobacco use would gain more weight during incarceration, in a penitentiary with a total tobacco ban, than inmates not in withdrawal from tobacco. We also hypothesised that inmates withdrawing from other substances (drugs and alcohol) would also gain more weight than inmates not going through withdrawal.

Materials and methods

This study is part of a larger research project that explored multiple determinants related to weight gain during incarceration in Canadian federal penitentiaries. Using the same methodology as described below, we also collected data on food intake33 and physical activity.34

Results

The participation rates were 45% (n=398/883 eligible inmates) for male inmates and 42% (n=45 participants/107 eligible inmates) for female inmates in Ontario. The participation rates were 47% (n=274 participants/583 eligible inmates) for male inmates and 64% (n=37 participants/58 eligible inmates) for female inmates in the Atlantic region.

Table 1 presents the proportion of inmates in each BMI category on admission and follow-up (mean duration of 5.0±8.3 years). It also shows how these proportions compare with the Canadian adult population (≥18 years of age) using data from Statistics Canada.43 The prevalence of obesity for the general Canadian adult population was 26.7% in 2015, similar to our inmate sample on admission to the penitentiaries (24.5%). However, 42.4% of inmates were considered obese at follow-up. This represents a 73% increase in inmates’ obesity rates between admission and follow-up. This comparison illustrates how inmates’ weight increased much more compared with the general population. Moreover, the observed weight gain is deemed undesirable since it results in an increase in the prevalence of inmate with obesity during incarceration (as opposed to seeing inmates come into the institution underweight and having normal BMI as a result of the weight gain).

Table 2 presents the sociodemographic characteristics (age, region and ethnicity) associated with history of tobacco use and substance misuse (drugs and alcohol). Younger age was associated with more drug misuse. Regional differences were also observed. A higher proportion of inmates from the Atlantic region reported smoking tobacco, were heavier smokers and reported alcohol misuse compared with inmates from the Ontario region. Inmates with Aboriginal backgrounds reported higher rates of smoking and substance misuse (drugs and alcohol). Sex and language were not associated with tobacco use or substance misuse (data not shown in the table).

Table 3 shows the waist circumference and BMI data at follow-up (measured at the time of the interview) for inmates with and without a history of tobacco use and substance misuse. We did not observe a significant difference in waist circumference and BMI between inmates with or without a history of tobacco use. But we observed that the proportion of inmates with high-risk waist circumference increased in a dose–response fashion with the number of cigarettes smoked prior to incarceration. Inmates with a history of tobacco use or drug misuse were also more likely to have a high-risk waist circumference and to be obese than those without a history of tobacco use and substance misuse. In addition, there was a strong positive correlation (r=0.82) between waist circumference and BMI at follow-up (data not shown).

Table 4 presents the data on median weight change, median BMI change and median annual weight change for inmates who had a history of tobacco use or substance misuse (drugs and alcohol) compared with inmates who did not. More than two-thirds (67.5%) of our sample reported tobacco use before incarceration. We found that ex-smokers gained roughly twice the amount of weight compared with non-smokers over time (7.5 kg vs 3.7 kg, respectively). Moreover, weight gain was related to the number of cigarettes smoked daily before incarceration, with heavy smokers gaining the most (light smokers (≤10 cigarettes/day) gained 5.6 kg vs 10.2 kg for heavy smokers (>25 cigarettes/day)). Approximately 50% of inmates reported a history of substance misuse prior to incarceration. These inmates gained 64% more weight, with a median weight gain of 7.4 kg, compared with 4.5 kg for inmates not battling an addiction to substances (drugs and/or alcohol) during incarceration. The type of substance was also associated with the amount of weight gained. The median weight gain for inmates with a history of drug misuse was three times higher than the weight gain of inmates with a history of alcohol misuse (8.4 kg vs 2.6 kg, respectively). Globally, BMI change and annual weight change followed a pattern similar to weight change.

Table 5 presents the results of a quantile regression coefficients analysis that confirms the association between BMI change and a history of smoking. For inmates from the groups with the highest weight change (75th and 90th percentiles), non-smokers had, respectively, 1.64 and 2.3 lower BMI points than ex-smokers. These findings also show similar findings for alcohol misuse. Moreover, BMI gain was significantly higher for inmates below the age of 45, for inmates of Aboriginal decent and inmates who were incarcerated the longest (length of incarceration >5 years). These findings were adjusted for sociodemographic factors (sex, age, region, language and ethnicity) as well as for other factors (length of incarceration, physical activity, feeding system and diet). Once findings were adjusted for confounders, the weight gain by number of cigarettes disappeared, suggesting the relationship was more influenced by another factor.

Discussion

The most important finding of this study is that ex-smokers who were forced to quit smoking during incarceration gained more weight, and at a faster rate, than non-smokers did (1.6 kg/year and 2.4 BMI increase for ex-smokers vs 0.9 kg/year and 1.2 BMI increase for non-smokers). This represents an overall gain of roughly twice the weight than non-smokers did (7.5 kg vs 3.7 kg for ex-smokers and non-smokers, respectively). This weight gain was deemed unhealthy since most inmates had a normal or overweight BMI on admission (33% had normal BMI and 42% had overweight BMI), then weight gain in prison (7.5 kg for ex-smokers) put a significant proportion of our sample in the obese range (BMI ≥30 kg/m²). Our findings revealed that obesity rates went from 25% on admission to 42% at follow-up (or time of the study), representing a 68% increase in obesity rates. Moreover, since most ex-smokers will likely resume smoking once released from prison,7 17 44 they may end up with two compounding risk factors for developing chronic diseases. Many inmates are already vulnerable to unhealthy weight gain by being incarcerated,26 and the added stress of involuntary tobacco cessation puts smokers at an even higher risk of becoming obese. This is important because a high proportion of inmates were smokers (67.5% of our sample) before incarceration, and it illustrates a need for more support for inmates withdrawing from tobacco during incarceration in Canadian penitentiaries.

Our findings are consistent with other studies on inmate addiction that found the prevalence for tobacco use and drug misuse to be three to four times higher in the inmate population (prior to incarceration) than in the general Canadian population.18 45 46 In our study, 67.5% of inmates reported a history of tobacco use, 43.4% of inmates reported illicit drug misuse, and 32.1% of inmates reported heavy alcohol use prior to incarceration, whereas in 2016, 16.9% of Canadians used tobacco,47 13% used illicit drugs,48 and 17.9% misused alcohol or were considered ‘heavy drinkers’ by WHO standards (ie, more than five drinks on one occasion at least once a month for the past 12 months).49 Overall, our findings showed that most inmates suffering from addictions (ie, tobacco and/or drugs) gained more weight during incarceration. Given the higher prevalence of tobacco and substance misuse, this puts a large proportion of inmates at increased risk of becoming obese and developing obesity-related illness.

It has been hypothesised by other authors that the rapid weight gain in the beginning of incarceration may be because inmates were withdrawing from alcohol, drugs and/or tobacco.28 50 In support of this hypothesis, studies from penitentiaries where tobacco was still permitted reported a modest weight gain (0.7–0.96 kg weight gain over 1–2 years).23 26 27 51 52 Contrary to Canadian data on inmate weight gain,25 these studies found that inmates were less likely to be obese than the general population,23 26 27 51 52 possibly in part because they were incarcerated in penitentiaries that still allowed smoking.

In prison, tobacco serves a range of functions, including being a surrogate currency, a means of social control, a symbol of freedom in a group with few rights and privileges, a stress reliever, and a social lubricant.4 53 Therefore, the importance of tobacco in the prison environment goes beyond what would be expected in the general population. These added functions of tobacco in prison should be taken into consideration when developing smoking cessation interventions. Furthermore, since before the ban tobacco and cigarettes were the main source of currency, now there are reports that inmates use junk food (chips, chocolate bars and soda drinks) as currency, to exchange services and to gamble.54 55 This new phenomenon may provide insight into the obesogenic effect of the tobacco ban. It may also go beyond smokers in prison, since it can potentially influence the obesogenic environment for everyone living in this environment. Now that junk food has become the new currency, it has become omnipresent in prison and therefore possibly consumed more frequently by all inmates.

The inclusion of tobacco cessation counselling and the use of cessation aids (such as nicotine replacement therapy) are deemed essential to long-term smoking cessation.13 30 56 57 In Canadian federal penitentiaries, these aids were available for inmates to purchase at the commissary store (or ‘canteen’). This means inmates are responsible for purchasing these items themselves (with their own funds). However, there are reports that inmates cannot afford these expensive cessation aids because of very low income during incarceration (daily salary ~$6 per day).58 This could, in part, explain why inmates gained more weight when in withdrawal from tobacco during incarceration, since they have limited access to tools that may help deal with cravings.17 Furthermore, without these tools, they may turn to food to manage tobacco withdrawal symptoms. This coping strategy appears to be permanent since weight gain is sustained over time. As such, inmates who are incarcerated longer (>5 years) gain significantly more weight than inmates with shorter sentences.

The tobacco ban in prison appears to be insufficient in obtaining long-term tobacco cessation.44 59 Most studies on the subject reveal that the vast majority of inmates (up to 97%) resume smoking within 6 months of being released back into the community.7 17 Consequently, once released inmates who smoke may end up with two compounding risk factors (tobacco and obesity), which put them at increased risk for health problems. The tobacco ban policy, intended to improve the prison health environment by improving air quality,60 has been successful at achieving this goal and also at reducing tobacco-related diseases.14 The risk of weight gain would unquestionably be offset by the benefits of long-term smoking cessation.61 62 However, this may not be the case for Canadian inmates who will likely resume smoking after incarceration, since evidence indicated most inmates resume smoking once released from prison.7 In light of this reality, there are programmes aimed at offering support to inmates with continued tobacco abstinence once released from prison. For example, WISE (Working Inside for Smoking Elimination) is a programme based on motivational interviewing and behavioural therapy out of the USA that has been successful at maintaining continued tobacco cessation postrelease from institutions where tobacco is forbidden.17 63 This type of programme could be helpful in Canada for inmates looking to achieve long-term smoking cessation. When planning for smoking cessation programmes for inmates, it is helpful to note that many inmates reported wanting to achieve something positive while in prison, and they say quitting smoking while in prison would be a great accomplishment.64 From this perspective, smoking cessation in prison could be viewed as a unique opportunity to help a population typically resistant to mainstream smoking cessation strategies.64 A WHO paper on tobacco bans in prison reported that inmates saw incarceration as an opportunity for smoking cessation and identified physical activity as a substitute for smoking.64 From a policy perspective, this means that including physical activity in a smoking cessation programme in prison could help inmates to quit smoking successfully and could also help with the unintended weight gain from smoking abstinence during incarceration. Moreover, physical activity could also potentially replace other above-mentioned functions related to tobacco in prison, such as acting as a stress reliever and a social lubricant.

In comparison with inmates who smoked, inmates suffering from drug withdrawal also gained more weight than inmates not going through withdrawal. They gained 8.0 kg compared with inmates without a history of drug use, who gained 4.5 kg, that is, a difference of 78% between these two groups. At follow-up, 87% of inmates with a history of illicit drug misuse were overweight or obese (BMI ≥25 kg/m²). This suggests the median 8 kg weight gain in those inmates did not help most of them go from underweight (since only 1.3% of our sample was underweight on admission) to a normal weight, but rather from a normal weight to overweight or obese. Prison staff often share the opinion that drug users enter prison underweight and the observed weight gain is deemed healthy, but our findings did not support this opinion. However, inmates withdrawing from alcohol misuse did not gain significantly more weight than inmates without a history of alcohol misuse, whereas the weight gain seen in inmates with a history of tobacco use or drug misuse was similar during incarceration.

Conclusion

In conclusion, inmates are vulnerable to weight gain during incarceration in part because of withdrawal from tobacco and drugs in Canadian penitentiaries. Although the decision to ban tobacco from penitentiaries contributes to a healthier environment in prison, the ban was suspected to have unintended consequences, and our findings have identified weight gain as one of those unintended consequences. Our findings suggest that tobacco ban in prisons could partly explain the large variation in weight gain seen in certain penitentiaries. For further research, a large-scale analysis examining weight gain data from penitentiaries where tobacco is banned, compared with penitentiaries where smoking is still permitted, could confirm our suspicion. Since many inmates view incarceration as an opportunity for smoking cessation, a carefully planned intervention programme (with postrelease support) could help empower inmates to abstain from tobacco long term. A follow-up study postrelease from prison to assess weight changes and smoking status could provide information on how to help inmates manage their addictions and their weight over time.