Health Promotion and Chronic Disease Prevention in Canada: Research, Policy and Practice

Highlights

Introduction

Excessive weight gain among youth is a public health problem, given the evidence that youth obesity is associated with a variety of immediate and long-term health effects including type 2 diabetes and heart disease.^{Footnote 1} Data from the 2009 to 2011 Canadian Health Measures Survey suggest that among Canadian youth aged 12 to 17 years, 29.6% of boys and 30.5% of girls were overweight or obese.^{Footnote 2} Considering that the prevalence of overweight and obesity among youth in Canada has increased dramatically in the past two decades,^{Footnote 3} a variety of prevention strategies and solutions have been developed to help stem this growing problem. These include both population-level^{Footnote 4Footnote 5} and clinical^{Footnote 6Footnote 7} approaches, generally focussed on achieving energy balance through increasing physical activity and improving diet.

In the domain of diet, the additional calories from sugar-sweetened beverage (SSB) consumption (e.g. fruit drinks or soft drinks) has recently received considerably more attention given their association with youth obesity.^{Footnote 8} In fact, a 2016 report by the Canadian Standing Senate Committee on Social Affairs, Science and Technology, Obesity in Canada: A Whole-of-Society Approach for a Healthier Canada, recommends the federal government consider a tax on SSBs.^{Footnote 9} However, while stakeholders work to develop strategies to stem SSB consumption in youth populations, little attention has been given to the potential impact of excess calories from alcoholic beverage consumption. Some evidence does exist highlighting an association between alcohol consumption and weight gain or obesity risk among youth,^{Footnote 10Footnote 13} especially among females.^{Footnote 12Footnote 13} Not only can alcohol represent a potentially significant source of calories (7.1 kcal/g) with limited to no nutritional value, but alcohol tends to be additive to caloric intake.^{Footnote 14Footnote 15} Alcohol intake can also act as an indirect risk factor for obesity through modified diet, such as increased food intake after alcohol consumption^{Footnote 15} and associations with disordered eating such as binge eating.^{Footnote 16}

The discussion around alcohol use and weight gain has generally been focussed on adult populations, and in fact little research is available on the link between alcohol use and weight gain or obesity in youth. High rates of frequent and heavy alcohol use are common among Canadian youth, with one 2011 study finding 25.5% of Grade 9 to Grade 12 students were considered current binge drinkers.^{Footnote 17} In addition, there is evidence that younger age of peak alcohol consumption is associated with both heavier drinking and obesity into adulthood.^{Footnote 18} Youth should therefore be considered a potential at-risk population when considering this link.

The COMPASS (Cohort Study of Obesity, Marijuana Use, Physical Activity, Alcohol Use, Smoking and Sedentary Behaviours) host study is a cohort study of secondary school students in Ontario and Alberta with the aim of measuring the impact of policy decisions on student health behaviours.^{Footnote 19} As part of this study, an annual student survey includes measures of drinking and binge drinking frequencies. Our study uses secondary data from the COMPASS study to produce conservative estimates of the potential total calories from alcohol use across different alcohol consumption patterns common among youth within the study. Considering there is ample literature discussing the problems associated with binge drinking during adolescence, the focus of this paper is not to make additional claims on the health risks of drinking, but rather to highlight the potential issue of additional calorie intake from alcohol consumption.

Methods

Design

This study uses secondary cross-sectional data from Year 2 (2013/14) of the COMPASS host study.^{Footnote 19}  Year 2 data were used because the first year of study consisted of a smaller sample of schools, and as such Year 2 comprised a larger sample of Grade 12 students. The data were collected using the COMPASS Student Questionnaire and active-information passive-consent procedures. All procedures were approved by the University of Waterloo's Office of Research Ethics and participating school boards. A full description of the study methods is available in print^{Footnote 19} or online (www.compass.uwaterloo.ca).

Measurements

This study is based on secondary data obtained from the student questionnaire. The COMPASS student-level questionnaire collects individual student data pertaining to multiple behavioural domains (e.g. alcohol use, tobacco use, obesity, physical activity, eating behaviour, etc.), correlates of these behaviours and demographic characteristics. In each school, the questionnaire was used to collect whole-school samples during class time. The questionnaire items were based on national standards or current national public health guidelines as described elsewhere.^{Footnote 19} 

Participants

In Year 2, 89 schools in Ontario (n = 79) and Alberta (n = 10) that approved the use of active-information passive-consent parental permission protocols were recruited to participate in COMPASS. Students could decline to participate at any time. The overall completion rate was 78.2% of enrolled students; the primary reason for nonparticipation was absenteeism at the time of the data collection. For the purpose of this paper, we used the Year 2 data from 10 144 students (4927 females, 5217 males) in Grade 12; previous research has demonstrated that the Grade 12 respondents (typically aged 16 to 18 years) have the highest rates of alcohol use.^{Footnote 17} Consistent with COMPASS data collection protocols, these students completed the COMPASS student questionnaire in class time on the day of their schools' scheduled data collection.

Measures

The two alcohol-consumption questions (on drinking frequency and binge drinking frequency) on the questionnaire are taken from existing national surveillance tools for youth populations in Canada.^{Footnote 20} The questionnaire defined one drink as "1 regular sized bottle, can or draft of beer, 1 glass of wine; 1 bottle of cooler; 1 shot of liquor; or 1 mixed drink" consistent with the standard serving sizes defined by the Canadian Centre on Substance Abuse (CCSA).^{Footnote 21}

Frequency of alcohol use. Drinking frequency was assessed by asking the question "In the last 12 months, how often did you have a drink of alcohol that was more than just a sip?" The response options were: "I have never drunk alcohol"; "I did not have a drink of alcohol in the last 12 months"; "I have only had a sip of alcohol"; "Less than once a month"; "Once a month"; "2 or 3 times a month"; "Once a week"; "2 or 3 times a week"; "4 to 6 times a week"; and "Every day." Response categories were combined to create five different frequencies of alcohol use: "Did not drink"; "Less than once per month"; "1 to 3 times per month"; "1 to 3 times per week"; and "4 or more times per week." The response rate for this question was 97.92%; students who did not respond to the question were excluded from the analyses.

Frequency of binge drinking. The binge drinking frequency measure provides additional insight into consumption levels by establishing a minimum threshold of five drinks per occasion. Respondents were asked "In the last 12 months, how often did you have 5 drinks of alcohol or more on one occasion?" The response options were "I have never done this"; "I did not have 5 or more drinks on one occasion in the last 12 months"; "Less than once a month"; "Once a month"; "2 to 3 times a month"; "Once a week"; and "2 to 5 times a week", or "Daily or almost daily." Response categories were combined to create five different frequencies of binge drinking: "Did not binge drink"; "Less than once per month"; "1 to 3 times per month"; "1 time per week"; and "2 or more times per week." The response rate for this question was 97.96%; students who did not respond to the question were excluded from the analyses. While the available questionnaire measure for binge drinking does not align with the low-risk drinking guideline for binge drinking among females (four or more drinks on one occasion),^{Footnote 22} the questionnaire measure is consistent with national youth surveillance measures^{Footnote 20} and provides a more conservative estimate of binge drinking among females.

Analyses

We calculated drinking and binge drinking frequencies by sex, and used chi-square tests to examine differences in drinking patterns by sex. We obtained the calorie content of various types of alcohol from Health Canada's Canadian Nutrient File (CNF)^{Footnote 22} and scaled for standard drink sizes using standard drink definitions from the CCSA.^{Footnote 21} The CNF database identifies 12 alcoholic beverages and corresponding calorie counts. We scaled calorie counts to standard drink sizes using the CCSA definitions: one serving is equal to one bottle of beer or cooler (341 ml [12 oz.]), one shot of liquor (43 ml [1.5 oz.]), or one glass of wine (142 ml [5 oz.]). Using the CNF list, we grouped drinks by approximate number of calories per standard serving to identify three representative drink classes of high, medium and low calorie content. Vodka coolers have a high calorie content, at 220 calories per standard serving. Regular beer (5% alcohol by volume) has a moderate calorie content, at 140 calories per standard serving. Light beer (4% alcohol by volume), table wines (red and white) and liquor shots (including gin, rum, vodka and whiskey) all contain approximately 100 calories per standard serving. We estimated the number of calories students consumed from alcohol for different generic types of alcoholic beverages according to average calorie content [vodka cooler; beer (5%); and beer (4%), wine and liquor], and for the five categories each for frequency of alcohol use and frequency of binge drinking. We converted the estimated total calories consumed over a one-year period to equivalent kilograms using the formula 7716 calories equal one kilogram.^{Footnote 23} We used SAS version 9.4 (SAS Institute Inc., Cary, NC, USA) for all statistical analyses. A significance level of p < .05 was used in all statistical tests.

Results

Drinking and binge drinking frequencies among the students in Year 2 are presented by sex in Table 1. Overall, 53.6% of students reported drinking alcohol at least once per month, while 18.7% reported drinking at least once per week. Although the prevalence of nondrinking was similar among males and females (24.1% and 24.4% respectively, p = .774), chi-square (Χ²) tests showed significantly different drinking patterns by sex (Χ² = 235.19, degrees of freedom [df] = 4, p < .001), with males drinking more frequently than females. Overall, 38.6% of students reported binge drinking at least once per month, while 11.4% reported binge drinking at least once per week. Chi-square tests showed significantly different binge drinking patterns by sex (Χ² = 194.60, df = 4, p < .001), with males binge drinking more frequently than females. Males were more than twice as likely as females to binge drink at least once per week (15.4% and 7.2%, respectively), and nearly three times as likely as females to binge drink two or more times per week (7.1% and 2.5%, respectively).

Calorie consumption estimates

Table 2 presents estimates for the total calories consumed over a one-year period by students who reported drinking at least once a month, by alcohol consumption frequency and beverage type. The results show high variability in the total calories consumed across the different beverage types and consumption frequencies. For instance, among the 15.7% of students who drank once per week, if we assume they only consumed one drink per occasion, they would have consumed between 5200 and 11 440 calories in one year (equivalent to 0.67 - 1.48 kg of fat). Among the 3.0% of students (4.6% of males, 1.4% of females) who drank four times per week, the total calories in one year would range from 20 800 to 45 760 (equivalent to 2.70 - 5.93 kg of fat). Figure 1 shows the calorie estimates, assuming one drink per occasion by beverage type and the percentage of students who fall into each estimation range.

Figure 1
Projections for additional calories consumed by students for one drink per occasion over a one-year period, by beverage type among Grade 12 students in Year 2 (2013/14) of the COMPASS Study, Ontario and Alberta, Canada

Among the 27.2% of students who binge drank once per month, if we assume they only consumed five drinks per binge drinking occasion, they would have consumed between 6000 and 13 200 calories in a one-year period (equivalent to 0.78 - 1.71 kg of fat; Table 2). Among the 4.9% of students (7.1% of males, 2.5% of females) who binge drank twice per week, the total calories in one year would range from 52 000 to 114 400 (equivalent to 6.74 - 14.83 kg of fat). Figure 2 shows the calorie estimates assuming five drinks per binge drinking occasion, by beverage type, and the percentage of students who fall into each estimation range.

Figure 2
Projections for additional calories consumed for five drinks per occasion over a one-year period by beverage type, among Grade 12 students in Year 2 (2013/14) of the COMPASS Study, Ontario and Alberta,

Discussion

Youth obesity is a complex public health issue, particularly since obesity in adolescence can lead to adverse health consequences in adulthood.^{Footnote 24} Obesity risk in youth is influenced by a variety of factors, including individual lifestyle factors such as food intake and physical activity.^{Footnote 6Footnote 11} While alcohol use is only one component of the issue, modifiable risk factors are often interrelated,^{Footnote 25} and these interrelationships should be recognized when developing public health interventions.^{Footnote 26} Current recommendations for preventing youth obesity do not generally include any considerations pertaining to alcohol use.^{Footnote 4Footnote 7Footnote 9} For instance, even in the recent Senate report on obesity in Canada,^{Footnote 9} none of the ^{Footnote 21} prevention recommendations designed to address youth obesity in Canada mentioned or considered the potential role of alcohol use. In our study, the majority of youth in our sample reported consuming alcohol and our estimates clearly show that even moderate levels of alcohol consumption can contribute to substantial caloric intake over the course of a year. Among the highest-risk students who report consuming a larger volume of alcohol on a frequent basis (more than 1 in 10 students in our sample), the volume of total calories from alcohol consumption is even more concerning. We believe that the evidence presented here indicates that alcohol use is a potentially meaningful contributor to youth overweight and obesity, and warrants consideration when developing obesity prevention strategies.

Strengths and limitations

In this paper, we are the first to provide very conservative estimates of the potential calories consumed per drinking occasion based on estimates of students consuming either one drink or five drinks per drinking occasion from a large sample of Canadian youth. However, data from the 2015 Ontario Student Drug Use and Health Survey (OSDUHS) suggests that youth drinkers typically report drinking two or more drinks per drinking occasion rather than one.^{Footnote 27} There is also emerging evidence to suggest that youth binge drinking episodes often involve 10 to 15 drinks per occasion rather than five.^{Footnote 28} Despite the fact that we are presenting very conservative estimates, our projections for total calories consumed from alcohol are still quite high across a variety of drinking patterns that are common among Canadian youth.^{Footnote 17-Footnote 29} 

These data are subject to limitations. While the type of drink can be an important factor in total estimated calories, no information was available on the type of drinks typically consumed by students in the sample. Calorie information on mixed drinks was not included in the analysis, given the variability in types of mixes and proportions, so our estimates did not include the additional calories that would also be consumed from the added mix (i.e. soft drinks or juice). Many common cocktails can contain up to 490 calories per drink,^{Footnote 30} which further suggests that our estimates are very conservative. The estimates given were also based on standard drink sizes. There is the potential for underestimation of total calories consumed if drinks are made larger than the standard size. For example, one pint of regular beer may be viewed as a single drink by respondents despite being the equivalent of 1.66 standard drinks. Additional information on the types of drinks commonly consumed would allow for more accurate estimation of calorie intake.

These results are based on a secondary data analysis from a sample that is not nationally representative. Thus, the drinking patterns identified here may not be representative of all Canadian youth. Furthermore, due to the secondary nature of the analysis, the available measures to assess drinking and binge drinking frequency do not allow for specific measurements of alcohol intake. Additional information is needed on the number of drinks typically consumed per occasion, along with more exact frequencies of the number of drinking and binge drinking occasions.

There are numerous health risks associated with binge drinking during adolescence.^{Footnote 31} While this study focussed on the potential additional caloric intake from alcohol consumption, there are many other negative immediate and long-term consequences of underage drinking that warrant consideration in public health interventions and education initiatives.

Conclusion

Despite the limitations discussed, this analysis has highlighted the need for researchers and stakeholders to consider alcohol more closely as a modifiable risk factor for overweight and obesity among youth. The high prevalence of frequent alcohol consumption and binge drinking by youth in this study, and the substantial number of calories contained in alcoholic beverages, suggest alcohol may be a key component of the obesity discussion that should not be overlooked.

Acknowledgements

The COMPASS study was supported by a bridge grant from the Canadian Institutes of Health Research (CIHR) Institute of Nutrition, Metabolism and Diabetes (INMD) through the "Obesity-- Interventions to Prevent or Treat" priority funding awards (OOP-110788; grant awarded to S. T. Leatherdale) and an operating grant from the CIHR Institute of Population and Public Health (IPPH) (MOP-114875; grant awarded to S. T. Leatherdale). Dr. Leatherdale is a Chair in Applied Public Health funded by the Public Health Agency of Canada (PHAC) in partnership with the CIHR Institute of Neurosciences, Mental Health and Addiction (INMHA) and IPPH.

Conflicts of interest

The authors state that they have no competing interests in this work.

Authors' contributions

KB performed the analyses, interpreted the results, wrote the first draft of the introduction and methods, and worked on drafting sections of the discussion for this manuscript. SL conceived the manuscript idea, led the COMPASS host study, wrote sections of the discussion, and edited all portions of the manuscript.