The section below summarizes scientific evidence on the impact of COVID-19 on the behavioural risk factors for chronic disease (i.e., nutrition, physical activity (PA), alcohol use, and tobacco use). Evidence documents include systematic reviews (SR), rapid reviews (RR), other types of reviews, and single studies. 

The methodological quality of some of the identified literature was rated using AMSTAR by McMaster Health Forum (please refer to their response document listed in the Methods section). The methodological quality of all other sources identified are included where available, or are unclear as the Research, Analysis, and Evaluation Branch does not have the expertise to make such assessments. 

Nutrition

• The research literature on the impact of the pandemic on nutrition is mixed, indicating both decreases and increases in healthy eating behaviours.
  • Three SRs and one review reported decreases in healthy eating behaviours during the pandemic. For example:
    • A SR (Oct 2021) including 23 longitudinal studies concluded that during the COVID-19 pandemic adherence to healthy diets decreased with a shift towards modified eating behaviours, characterized by increased snack frequency and a preference for sweets and ultra-processed food rather than fruits, vegetables, and fresh food.
    • A SR (Apr 2021) found that snacking increased for a significant portion of the population examined (18.9-45.1%); whereas fast food (15.0-41.3%) and ordered food (33.9%) showed a decreasing tendency.
    • A SR (Apr 2021) reported an overall increase in food consumption, bodyweight (BW), Body Mass Index (BMI), and a change in eating style.
    • A review (Mar 2021) concluded that the COVID-19 lockdown both negatively and positively impacted dietary practices throughout Europe and globally; negative diet habits were associated with weight gain, mental health issues, and limited PA.
  • Single studies from the United States (US) and Japan also reported mixed results. For example, in the US, 59.8%, 16.4%, and 23.4% of study participants reported that their eating habits likely changed, may have changed, and likely did not change, respectively. Of the participants whose dietary habits likely or may have changed, 64.1%, 16.8%, and 19% reported healthier, neither healthier nor less healthy, and less healthy eating habits, respectively.
• Adherence to a Mediterranean Diet (MD): A SR (Dec 2021) concluded that changes in the intake of major food groups, apart from fish intake, were in line with the definition of a traditional MD, indicating a consistent moderate improvement of dietary habits worldwide. Another SR (Oct 2021) found that evidence indicates that consumption of MD food items increased during lockdown but evidence is heterogeneous in study design, quality, and findings.
• Children’s Dietary Changes: A SR (Sept 2021) noted that current evidence does not allow for persuasive conclusions about changes in dietary quality for children during the pandemic so there is an urgent need for more high-quality research in this area.
• Increased BW and BMI in Adults, Adolescents, and Older Adults: A SR (Apr 2021) reported an overall increase in food consumption, BW, BMI, and a change in eating style as a result of the pandemic. Another SR and meta-analysis (Apr 2021) observed a significantly higher BW and BMI in adults and adolescents (>16 years old) in the post-lockdown period (March-May 2020) compared to before lockdown. The SR reported that further studies are needed to assess potential group-specific impacts, regarding weight gain in younger people and risk of weight loss, malnutrition, and loss of muscle tissue in older adults.
• Increased Food Insecurity: A SR (Aug 2021) found that the pandemic impacted diet quality and food security in low- and middle-income countries, raising concerns about the long-term impact on access to and affordability of nutrient-rich, healthy diets and their health implications. Women and individuals with a low socio-economic status are likely to be the most at risk of food insecurity. A RR (Jun 2021) found that food insecurity appears to be more prevalent during the COVID-19 pandemic than before, particularly among low-income populations across studies that included comparisons to pre-pandemic levels: change in prevalence of food insecurity in the general population during the pandemic ranged from -2.8% to 4.1% in Canada and -0.7% to 26.2% in the US. A Canadian study (2021) found that nearly one in five participants worried about having enough food to meet their household’s basic needs in May 2020.
  • Food Insecurity in Vulnerable Populations: The RR (Jun 2021) also reported that change in the prevalence of food insecurity among low-income populations during the pandemic ranged from 10% to 47%.
  • Food Insecurity and Mental Health: The Canadian study (2021) noted that the relationship between food insecurity and mental health was magnified among vulnerable groups, including those in the lowest income category, people with a disability, and racialized and Indigenous peoples. The relationship between food insecurity and mental health is well-established and has shown to be independently associated with experiences of mental distress and mental health conditions.

Physical Activity (PA)

• Four reviews found a decrease in PA levels and/or an increase in sedentary behaviour associated with the COVID-19 pandemic. For example:
  • A SR (Jan 2021) found changes in PA reported in 64 studies, with the majority reporting decreases in PA and increases in sedentary behaviours during their respective lockdowns across several populations, including children and patients with a variety of medical conditions (e.g., eating disorders, diabetes).
  • A single study (May 2021) in the UK found that relative to pre-pandemic levels, participants spent half a day less per week doing ≥30 min of moderate to vigorous physical activity (MVPA), but slightly increased days of strength training.
• Mental Health Impacts: Three SRs found either an increase in sedentary time or a decrease in PA was related to poor mental health outcomes during the pandemic. In particular:
  • A SR and meta-analysis (Oct 2021) found increases in sedentary time were negatively correlated with global mental health, depression, anxiety and quality of life, irrespective of age. Similarly, another SR (Dec 2020) demonstrated an association between mental health distress (e.g., stress, anxiety, depressive symptoms, social isolation, psychological distress) and PA (i.e., adults increased their sedentary time and reduced their PA levels).
  • A rapid SR (Apr 2021) found that people who performed PA on a regular basis with higher volume and frequency and kept the PA routines stable, showed less symptoms of depression and anxiety. For instance, those reporting a higher total time spent in MVPA had 12-32% lower chances of presenting depressive symptoms and 15-34% of presenting anxiety.
• Children and Adolescents: A review (Oct 2021) highlighted a decrease in children and adolescent PA during the pandemic, ranging between -10.8 min/day and -91 min/day. Another review (Jul 2021) that found PA in children and/or adolescents decreased during the pandemic included 18 studies mostly from Europe, but also Canada, the US, and South America. It noted that: 1) the decrease in PA was more prevalent in boys and older children and adolescents; 2) the decrease in PA was less prevalent in children who live in detached houses, houses with more space, rural areas, and with more family members; and 3) parental support and consideration of location and activity types may help children maintain or increase their PA during the pandemic.
  • Canada: A Canadian survey (Apr 2020) found that only 4.8% (2.8% girls; 6.5% boys) of children and 0.6% (0.8% girls; 0.5% boys) of youth were meeting combined movement behaviour guidelines during COVID-19 restrictions.
  • Italy: A study (Jan 2022) of primary school children found weekly and daily minutes time spent in MVPA significantly decreased from before to during pandemic, while the weekly time spent in sedentary behaviour increased.
• University Students: Two SRs found reduced PA among most university students, but mixed results for those who had been active/less sedentary after lockdown. A SR (Sept 2021) found that COVID-19-related lockdowns appear to have negatively affected walking and sedentary behaviour among undergraduate students but not among graduate students. Students who were more sedentary before lockdown increased or did not change their MVPA. In contrast, those who were less sedentary before lockdown decreased their MVPA. Another SR (Jan 2021) found that walking, moderate, vigorous, and total PA levels have been reduced during the COVID-19 pandemic confinements in university students of different countries. Despite the reductions, those who met the current minimum PA recommendations before the lockdown generally met the recommendations also during the confinements.
• People with Chronic Disease (CD): Two SRs and one RR demonstrated reduced PA with people who already experience barriers to PA because of a chronic condition (i.e., those with physical disabilities and/or chronic disease/conditions) across various jurisdictions.
  • A SR (Jun 2021) in Italy found most studies highlighted a significant reduction in the amount of performed PA compared to before lockdown, in both the general population and in individuals with chronic conditions. This outcome had negative consequences on both general health, in terms of increased body mass, and on specific chronic conditions, especially obesity and neurological diseases.
  • A SR (Nov 2021) that included studies from Saudi Arabia, Brazil, Israel, Spain and the Republic of Macedonia demonstrated that PA levels during the COVID-19 pandemic were reduced with respect to previous levels of PA in patients with CD. Some included studies showed an increase of sedentary behaviour during the pandemic, an increment in time spent on social media, a deterioration in mental health and healthy behaviours such as vegetable consumption, and the feeling that in general, people were eating more compared to pre-pandemic levels.
  • A RR (Jun 2021) including 29 studies from 21 different countries (e.g., Italy, India, US, Belgium, China, France, the Netherlands) found that almost all studies reported negative impacts on PA and well-being (e.g., increases in stress, anxiety, depression) in people with health conditions or chronic diseases (e.g., diabetes, Parkinson’s, cardiovascular disease [CVD], cystic fibrosis) during the first wave of the pandemic.
• Professional Athletes: A SR (Sept 2021) on the PA, mental state, and quality of life of professional athletes found a decrease in overall physical fitness and number of days and hours of training, as well as an increase in the occurrence of negative emotions (stress, fatigue, and depression) and a decrease in sleep quality. Women were more likely to experience negative emotions compared to men.

Substance Use

Most of the information identified on the impact of the pandemic on substance use focused on alcohol and tobacco. 

• Alcohol Use: Overall, the evidence from three SRs, one review, and one study showed an increase in alcohol consumption during the pandemic. For example, one SR (Oct 2021) found increased alcohol consumption reported among different countries (e.g., China, Japan, UK). Another SR (Dec 2021) noted an overall trend towards increased alcohol consumption during the pandemic with the proportion of people consuming alcohol ranging from 21.7% to 72.9% in general population samples.
  • Canada: A RR (Jun 2020) noted that low quality evidence from studies conducted in Canada suggests that more people have increased their alcohol intake during the pandemic rather than decreased, particularly in younger people aged 18-34 years. For example, a study from the Canadian Centre on Substance Use and Addiction found that compared to pre-pandemic alcohol intake, a survey of adults (n=1,009) in Canada aged 18 years and older who reported staying home more during the pandemic found: 20% reported an increase in alcohol intake; 10% reported a decrease; and 47% reported no change in alcohol intake.
  • Alcohol Use and Mental Health: A SR (Dec 2021) noted that mental health factors were the most common correlates or triggers for increased use of both alcohol and other substances, including cannabis. Further, a SR (Nov 2021) noted that the clearest negative substance use outcomes in the context of COVID-19 are among people who have a history of problems related to their substance use and concurrent disorders. For example, studies indicated that people who already drank in risky ways before the pandemic were more likely to increase their substance use during the pandemic. International single studies also reported similar findings:
    • Canada: A survey (Nov 2021) of Canadian adults found that 16.2% of women and 15.2% of men self-reported an increase in their alcohol consumption from September to December 2020. During the same period, 4.9% of women and 5.8% of men self-reported an increase in their cannabis consumption. For men and women, screening positive for symptoms of depression was significantly associated with higher odds of increased alcohol and cannabis use. Another survey (Aug 2021) of Canadian adults also found that changes in alcohol consumption were positively associated with anxiety, feeling depressed, and loneliness. People with mild to moderate or severe anxiety had greater odds of increased drinking than did people with no to low levels of anxiety.
    • Australia, UK, and US: Two single studies from the US, one from Australia, and one from the UK found increased alcohol use in adults in the spring of 2020 and that was associated with mental health outcomes. For example, one in ten US adults over the age of 55 (717/6,548; 11%) reported an increase in their alcohol consumption in the past week compared to their usual pre-COVID-19 drinking, which was associated with depression, anxiety, and loneliness. In the UK, of 691 adults, 17% reported increased alcohol consumption after lockdown with a higher proportion being those aged 18-34 years of age. There was also a significant association between increased alcohol consumption and poor overall mental health (e.g., depressive symptoms, mental wellbeing).
  • Indigenous People: A nationally representative Canadian survey (Apr 2021) on self-reported mental health during the first wave of COVID-19 found that within the overall sample, 19.5% indicated that their use of alcohol had increased because of the pandemic, and the group most likely to report increased alcohol use was Indigenous people (24.4%). Similarly, a study (Nov 2021) from British Columbia on marginalized groups (including Indigenous peoples) found increased alcohol use relative to pre-pandemic levels, with women reporting a greater increase than men.
• Tobacco Use: A RR (Nov 2020) found there was no clear direction of effect of the COVID-19 pandemic on use of tobacco or vaping products. Most studies reported a mixed result: some smokers increased their use during the pandemic, some decreased their use, and others did not change their use. The factors associated with an increase versus a decrease in smoking were not clearly identified in the research. The RR also reported that there was no clear effect of the COVID-19 pandemic on cessation or cessation attempts. Similarly, a SR (Mar 2021) found that while two studies reported that tobacco users have successfully quit during lockdown period, three studies suggested that users have become more addictive to smoking due to psychological stress experienced during the pandemic.
  • British Columbia: A study (Nov 2021) on marginalized groups (including Indigenous peoples) found increased cannabis use relative to pre-pandemic levels, with women reporting a greater increase than men.
  • Iceland: In a study (Aug 2021) of adolescents, cigarette smoking, and e-cigarette use declined among 15-18 year olds during COVID-19, possibly due to an unintended benefit of isolation. The study also found an increase in depressive symptoms and worsened mental wellbeing across all age groups during the pandemic compared with same-aged peers before COVID-19. These outcomes were significantly worse in adolescent girls compared with boys.

Future Research

• Protocols for SRs currently underway include topics such as the effects of the COVID-19 pandemic on the general populations’ mental health, alcohol/substance abuse and violence, and lifestyle factors (i.e., smoking, BMI, PA, and dietary habits) and COVID-19. For a list of other protocols on related topics, see Al-Khateeb et al. (2022).

The COVID-19 Evidence Synthesis Network is comprised of groups specializing in evidence synthesis and knowledge translation. The group has committed to provide their expertise to provide high-quality, relevant, and timely synthesized research evidence about COVID-19 to inform decision makers as the pandemic continues. The contents of this Evidence Synthesis Briefing Note are not intended to serve as guidance, but rather reflect the available evidence at the time of writing. The following members of the Network provided evidence synthesis products that were used to develop this Evidence Synthesis Briefing Note:

• Al-Khateeb S, Bain T, Mansilla C, Lavis JN, Wilson MG. COVID-END in Canada existing resource response #14: How has the COVID-19 pandemic (e.g., public-health measures, such as lockdowns) impacted risk factors for chronic disease? Hamilton: McMaster Health Forum, COVID-END in Canada, 6 February 2022.
• Evidence Synthesis Unit, Research Analysis and Evaluation Branch, Ministry of Health. January 31, 2022.

For more information, please contact the Research, Analysis and Evaluation Branch (Ministry of Health).