Changes in Diet, Physical Activity, Alcohol Consumption, and Tobacco Use in Adults During the COVID-19 Pandemic: A Systematic Review

Abstract

The COVID-19 pandemic changed various lifestyle habits worldwide due to the prevention measures implemented in each country, these changes may affect or benefit people’s health. We aimed to systematically review changes in diet, physical activity (PA), alcohol consumption, and tobacco use habits during the COVID-19 pandemic in adults. Two databases: PubMed and ScienceDirect, were used for this systematic review. The research was limited to open-access, peer-reviewed original articles published in English, French, or Spanish from January 2020 to December 2022 and investigated diet, PA, alcohol consumption, and tobacco use habits before and during the COVID-19 pandemic in adults. Excluded studies were review studies, intervention studies with a sample size of fewer than 30 participants, and poor-quality articles. This review followed PRISMA 2020 guidelines (PROSPERO: CRD42023406524), whereas to assess the quality of the studies, we used the quality assessment tools developed by the BSA Medical Sociology Group for cross-sectional studies and the QATSO for the longitudinal studies. Thirty-two studies were included. Some studies reported changes to promote healthy lifestyles; 13 out of 15 articles reported an increase in healthy diet consumption habits, 5 out of 7 studies reported a decrease in alcohol consumption, and 2 out of 3 studies reported a decrease in tobacco use. On the other hand, the other studies reported changes to promote unhealthy lifestyles: 9 out of 15, and 2 out of 7 studies reported an increase in unhealthy diet and alcohol consumption habits respectively, 25 out of 25 reported a decrease in physical activity, and 13 out of 13 reported an increase in sedentary behavior. During the COVID-19 pandemic, there have been changes to promote a healthy and unhealthy lifestyle; the latter can affect people’s health. Therefore, effective responses are needed to mitigate the consequences.

• What do we already know about this topic?

• ● Lifestyle has a significant influence on physical and mental health. An unhealthy lifestyle is a risk factor for various diseases, and a healthy lifestyle is recommended for preventing various diseases and maintaining good health.

• How does your research contribute to the field?

• ● This systematic review highlights diet, physical activity, alcohol consumption, and tobacco use habits changes during the COVID-19 pandemic in adults worldwide and shows the changes that may promote healthy or unhealthy lifestyles.

• What are your research’s implications for theory, practice, or policy?

• ● Following this thread, public health institutions will have evidence-based information to know where to focus efforts that help mitigate unhealthy lifestyles. The strategies could be implemented considering the health consequences in the short and long term.

Introduction

The COVID-19 pandemic was caused by a new coronavirus SARS-CoV-2. ¹ Due to its rapid spread and increased morbidity and mortality worldwide, many countries implemented various preventive measures. ² These actions may affect lifestyle habits, and consequently, the population’s health.

A healthy lifestyle is important for the prevention of various diseases and for maintaining good health. According to the World Health Organization, eating healthy food helps prevent malnutrition and chronic diseases. On the other hand, unhealthy foods such as high-calorie foods, insufficient fruits and vegetables, and low fiber and high salt content consumption have been associated with several chronic diseases. ⁵⁰ During the pandemic, an increase in stress, anxiety, depression, and insomnia was observed, as well as a decrease in concentration or work performance, and these changes could also affect dietary behavior. A study reported by Ramón-Arbués et al ⁴ in Spain showed that the presence of anxiety, depression, stress, and low-quality sleep affects food choices and is also associated with an elevated consumption of unhealthy foods such as products high in carbohydrates and fats.

Regular physical activity is beneficial for physical and mental health, preventing various diseases like type 2 diabetes, hypertension, anxiety, and depression, among others. The World Health Organization recommends that all adults perform physical activity for at least 75 min of high intensity or at least 150 min of moderate-high intensity combined per week to be physically active and get this benefits. ⁵¹

Alcohol consumption is related to a whole series of health problems, including mental and behavioral disorders. Alcohol dependence is associated with severe non-communicable diseases, such as liver cirrhosis, some types of cancer, and cardiovascular diseases, and is also associated with injuries and deaths due to violence and traffic accidents.^52,53

Tobacco use causes a series of widely known alterations, such as coronary heart disease, cerebrovascular disease, and cancers of the lung, oral cavity, larynx, esophagus, stomach, kidney, pancreas, and cervix, among others. ⁵³

It seems that the COVID-19 pandemic had an impact on lifestyle factors such as changes in physical activity, eating behaviors, alcohol consumption, and tobacco use. ³ Confinement at home, coupled with an unhealthy lifestyle, may cause mental health problems such as anxiety, stress, and depression, which may be associated with eating disorders and alcohol consumption.^4,5 On the other hand, the pandemic of COVID-19 may promote a healthy lifestyle due to the longer time that people stay at home, compared to the pre-pandemic period. ⁴² Currently, there is interest in knowing and evaluating whether the various restriction measures due to the pandemic caused lifestyle changes and whether these changes are healthy or unhealthy.

Currently, no systematic review has addressed changes in lifestyle habits comparing the periods before and during the COVID-19 pandemic in adults, nor the type of changes that occurred. Therefore, this review aims to understand to what extent diet, alcohol consumption, tobacco use, and PA habits have changed due to the COVID-19 pandemic and to assess whether these changes are healthy or unhealthy. Following this thread, strategies can be visualized to prevent the health consequences that lifestyle changes may have in a short-, medium-, and long-term period.

Methodology

This review was designed and conducted based on the PRISMA 2020 statement. ⁶ Additionally, the manuscript was registered in the International Prospective Register of Systematic Reviews database (PROSPERO) (registration number CRD42023406524). The 2 potential electronic databases, PubMed and Science Direct were used by 2 independent researchers. The first researcher applied eligibility criteria, selected studies for inclusion in the systematic review, and performed the data extraction; the second researcher checked the decisions. The disagreements between researchers’ judgments were resolved based on each researcher’s justification and the study’s aim, and Mendeley was used to record the decisions. The data extracted were: authors, publication year, location, study design, participant number, median or range of age, variables evaluated in each study before and during the COVID-19 pandemic related to diet, physical activity, tobacco use, and alcohol consumption habits, and a P value. The Excel spreadsheet was used to record data.

Quantitative and narrative methods were used for data synthesis. The data for each lifestyle reviewed were synthesized separately. In each lifestyle, we analyzed how many articles reported changes to promote healthy or unhealthy lifestyles and whether there was an increase or decrease in variables studied in each article related to diet, physical activity, tobacco use, and alcohol consumption habits reported in articles from before compared to during the COVID-19 pandemic. The measures considered are the means, frequencies, or percentages of variables studied in each lifestyle.

The following keywords were used to find the relevant articles: dietary habits (title/abstract) OR physical activity (title/abstract) OR alcohol consumption (title/abstract) OR tobacco consumption (title/abstract) AND COVID-19 pandemic (title/abstract). Based on these keywords, we reached the following advanced search strategies in PubMed: Search (( OR (alcohol consumption [title/abstract]))((dietary habits [title/abstract]) OR (physical activity [title/abstract])) OR (tobacco consumption [title/abstract])) AND (COVID-19 pandemic [title/abstract]). The full search strategies for all databases are in the supplement material.

The inclusion criteria applied in this study focused on the characteristics of the article, study design, sample size, study population, publication year, and type of lifestyle habit. The research was limited to open access and peer-reviewed original articles published from January 2020 to December 2022 that reported on dietary habits, PA, consumption of alcohol, and tobacco use before and during the COVID-19 pandemic. In addition, participants must be 18 years of age or older, and cross-sectional and longitudinal studies published in English, French, or Spanish, from any country, were allowed. The translation of Spanish and French articles into English was made by the researchers. Studies excluded were those reporting the lifestyle changes mentioned above based on a diagnosed condition, intervention or studies focused on a specific group of people. We excluded studies assessing lifestyle during the pandemic but did not show how the lifestyle habit was before the pandemic. We also excluded qualitative studies, systematic, narrative, meta-analysis review studies, and those that had a sample size of fewer than 30 participants. We also excluded short communication articles.

The quality assessment tools developed by the BSA Medical Sociology Group were used for the quality assessment of cross-sectional studies, where the quality indicators met out of 7: 1 to 2 (low), 3 to 5 (moderate), and 6 to 7 (high). The QATSO was used for the longitudinal studies, where the quality indicators met out of 100%. Studies achieving 67% or more in the score were regarded as “good” quality, 34% to 66% (fair), and below 33% (poor).^48,49 The articles of low or poor quality were removed. The PRISM diagram for the systematic review process for identifying articles included in this review is presented in Figure 1.

Figure 1.

PRISMA 2020 flow diagram of the study selection process.

Results

A total of 4037 articles from 2 databases were initially identified, and finally, 32 peer-reviewed original articles were selected as eligible to be included in this study (Figure 1). The characteristics of the articles are presented in Table 1. We included 28 cross-sectional studies^{7,8,10,12-24,26-31,33-38},4 longitudinal studies.^9,11,25,32 There is one global study, ³⁸ and 2 or more studies covered different countries: 2 from Saudi Arabia.,^7,24 5 from Spain^{10,25,33,34,36},4 from USA^11,14,27,29,2 from the UK^17,32,3 from Italy,^20,26,37 and 2 from China.^13,28 Other countries that were included in one study were Japan, ⁹ Lithuania, ¹² Canada, ¹⁶ Germany, ¹⁸ Australia, ²¹ Finland, ²² Hong Kong, ³⁰ Sweden, ³¹ Rusia, ³⁵ Thailand, ⁸ Mexico, ¹⁵ Brasil, ¹⁹ and Turkey. ²³

Table 1.

Studies and Participants’ Characteristics.

Ref. Num	First author/Year	Location	Study Type	Participants number	Median age or range	Study quality	Study language
24	Abdulsalam et al (2021)	Saudi Arabia	Cross-sectional study	472 GP	18-59	Moderate	English
15	Alarcón Meza and Hall-López (2020)	Mexico	Cross-sectional study	32 US	21	Moderate	Spanish and English
38	Ammar et al (2020)	World	Cross-sectional study	1074 GP	18 and above	Moderate	English
27	Barbosa et al (2021)	USA	Cross-sectional study	555 GP	21 and over	Moderate	English
16	Bertrand et al (2021)	Canada	Cross-sectional study	125 US	18-64	Moderate	French and English
23	Bosi Bağcı et al (2021)	Turkey	Cross-sectional study	340 US	24.89	High	English
21	Callinan et al (2021)	Australia	Cross-sectional study	2307 GP	18 and above	Moderate	English
29	Chen et al (2021)	USA	Cross-sectional study	2709 GP	18 and over	Moderate	English
32	Dicken et al (2021)	UK	Longitudinal study	1733 GP from before March 2020 to November 2020	18 and above	Good	English
31	Elvén et al (2022)	Sweden	Cross sectional study	1035 GP	18-79	High	English
10	Franco et al (2021)	Spain	Cross-sectional study	297 GP	24-63	Moderate	English
37	Gallè et al (2020)	Italy	Cross-sectional study	1430 US	22.9	Moderate	English
18	Helbach and Stahlmann (2021)	Germany	Cross-sectional study	884 GP	18-26	Moderate	English
25	Imaz-Aramburu et al (2021)	Spain	Longitudinal study	264 US from September 2019 to September 2020	20.19	Fair	English
8	Katewongsa et al (2020)	Thailand	Cross-sectional study	4460 GP in March 2019 & 4482 in March 2020	18-64	Moderate	English
35	Kontsevaya et al (2021)	Russia	Cross-sectional study	2432 GP	18 and above	Moderate	English
9	Koohsari et al (2021)	Japan	Longitudinal study	2466 GP in February 2019 and 1086 in July 2020	20-59	Fair	English
34	Maestre et al (2021)	Spain	Cross-sectional study	1640 GP	18 and above	Moderate	English
26	Mascherini et al (2021)	Italy	Cross-sectional study	1383 US	31.5	Moderate	English
17	Rao et al (2022)	UK	Cross-sectional study	366 GP	55-74	Moderate	English
11	Rees-Punia et al (2021)	USA	Longitudinal study	1992 GP from summer 2018 to summer 2020	57	Good	English
33	Rodríguez-Larrad et al (2021)	Spain	Cross sectional study	13754 US	18-54	Moderate	English
20	Roggio et al (2021)	Italy	Cross-sectional study	1654 US	22.51	Moderate	English
36	Sánchez-Sánchez et al (2020)	Spain	Cross sectional study	1073 GP	38.7	Moderate	English
22	Sandell and Saltychev (2021)	Finland	Cross-sectional study	76 US	21	High	English
19	Schuch et al (2022)	Brazil	Cross-sectional study	877 GP	18-65	Moderate	English
14	Sidebottom et al (2021)	USA	Cross-sectional study	291 CS	18-24	Moderate	English
12	Skurvydas et al (2021)	Lithuania	Cross-sectional study	6369 GP in October 2019 & 2392 in November 2020	18-74	High	English
7	Sultan et al (2021)	Saudi Arabia	Cross-sectional study	338 GP	40	Moderate	English
28	Wang et al (2021)	China	Cross-sectional study	1028 GP	19-59	Moderate	English
30	Wang et al (2021)	Hong Kong	Cross-sectional study	724 GP	18 and above	High	English
13	Yang and Ma (2021)	China	Cross sectional study	6659 GP	38.45	Moderate	English

Note. Ref = Reference; GP = General Population; US = University Students; CS = College Students; UK = United Kingdom; USA = United States of America.

Some studies reported on more than one lifestyle habit. The included studies focused on the habit changes of:

• Diet: 15 studies^{7,10,12,14,16,23-26,29,30,32,34,36,38}

• Physical activity (PA): 25 studies^{7-12,14-16,18-20,22,24-26,28-31,33,35-38}

• Alcohol consumption: 7 studies^{12,14,17,21,22,27,29}

• Tobacco use: 3 studies^7,13,24

During the analysis of these lifestyle changes, 8 research themes were generated. These include dietary habits changes (food groups recommended for daily consumption and food groups not recommended for daily consumption), PA changes (PA level and sedentary behavior), alcohol consumption changes (frequency and quantity), and tobacco use changes (frequency and quantity of cigarette use habits).

Changes in Dietary Habits During the Pandemic of COVID-19

In this review, we analyzed changes in dietary habits during the pandemic based on the change in consumption frequency of foods, and the number of populations that consumed each food group (the recommended and non-recommended food groups for daily consumption).

Food groups recommended for daily consumption are defined as those for which there is evidence that daily consumption is not associated with chronic diseases or a high risk of being overweight or obese. These groups are fruits, vegetables, legumes, unprocessed meats, water, eggs, and dairy. The food groups not recommended for daily consumption are those whose frequent consumption is associated with a high risk of obesity and overweight, as well as chronic diseases. These groups are fast foods, snacks, processed meats, sweet cereals, sweetened non-dairy beverages, and sweet ened dairy beverages. ³⁹

Fifteen studies reported changes in diet habits during the COVID-19 pandemic (Table 2). Thirteen studies^{7,10,12,14,16,23-26,30,32,34,36} reported a significant change in the frequency of consumption and the proportion of individuals who consumed food groups recommended for daily consumption. Eleven out of thirteen studies reported changes toward a healthy lifestyle where there was an increase in fruit consumption, legumes, vegetables, adherence to the Mediterranean diet, water, and homemade meals during the pandemic compared to before the pandemic. Mascherini et al ²⁶ reported an increase in consumption frequency per week of fruits, legumes, vegetables, and the Mediterranean diet during the pandemic. These results are supported by 2 other studies.^14,30 Sultan et al ⁷ reported an increase in people who consumed fruits or vegetables every day from 47.2% before the pandemic to 60.2% during the pandemic. This result was supported by 7 other studies that reported an increase in the percentage of individuals consuming fruits, vegetables, legumes, a Mediterranean diet, water, and homemade meals every day during the pandemic.^{10,12,23-25,34,36} By contrast, only 2 out of 13 studies reported changes toward unhealthy lifestyles, such as a decrease in the consumption frequency of fruits, vegetables, and dairy products during the pandemic of COVID-19.^16,32

Table 2.

Changes in Dietary Consumption Habits During the Pandemic of COVID-19 (n = 15).

Articles references	Findings
	Variables Evaluated in each Study	Before	During	P value
Sultan et al 7	Participants ate fast food	71.9%	47%	<.001
	Participants ate fruits or vegetables every day	47.2%	60.2%	<.001
	Adults consumed caffeinated beverages(≥7 times per day)	0.9%	3%	<.001
	Participants consumed water (≥8 cups of water per day)	11.9%	18.4%	<.001
Franco et al 10	Participants had adherence to the Mediterranean diet	54.5%	76.4%	<.001
Skurvydas et al 12	Participants never over eat	18.2%	20.8%	>.05
Sidebottom et al 14	Consumption frequency of meals at home per week	4 times	6 times	<.001
	Consumption frequency of meals outside of home per week	3 times	2 times	.884
	Consumption frequency of fruits per week	4 times	5 times	.034
	Consumption frequency of vegetables per week	1 time	2 times	.981
Bertrand et al 16	Beverages (frequency/day)	1.2 times	0.6 time	<.005
	Coffee and Tea (frequency/day)	3.3 times	2 times
	Grains (frequency/day)	1 time	.9 time
	Fruits (frequency/day)	1 time	.8 time
	Vegetables(frequency/day)	1.3 times	.7 time
	Dairy (frequency/day)	1.7 times	.9 time
	Nuts (frequency/day)	0.8 time	.3 time
	Meat (frequency/day)	1.5 times	1.2 times
	Snacks (frequency/day)	1.1 times	.8 time
Bosi Bağcı et al 23	Students described their dietary habits as healthy	30%	48.8%	<.001
	Students had breakfast regularly	50%	80.9%	<.001
	Students ate snacks regularly	16.8%	38.2%	<.001
	Students eating outside	97.6%	19.4%	<.001
	Students order food from outside	91.8%	32.8%	<.001
Abdulsalam et al 24	Participants ate healthy food	2.1%	3.6%	.865
	Participants ate homemade meals every day	26.9%	56.4%	.000
	Participants ate always snacks or meals late at night	8.9%	16.5%	.000
Imaz-Aramburu et al 25	Students had adherence to the Mediterranean diet	61.4%	68.2%	.005
	Students ate vegetables daily	59.8%	65.8%	.048
	Students ate red meats daily	68.8%	75.9%	.061
	Students ate nuts daily	56.2%	62.2%	.076
Mascherini et al 26	Med Diet Score per week	31 points	31.1 points	.153
	Consumption frequency of cereals per week	1.7 times	1.9 times	<.001
	Consumption frequency of fruits per week	2.4 times	2.5 times	<.001
	Consumption frequency of vegetables per week	2.5 times	2.5 times	.283
	Consumption frequency of legumes per week	2 times	1.9 times	.001
	Consumption frequency of red meat per week	3.4 times	3.5 times	.002
Chen et al 29	Consumption frequency of fast food per week	1.4 times	0.9 time	<.001
Wang et al 30	Frequency of dining out per week	2.3 times	1.1 times	<.001
	Frequency of ordering takeaway per week	0.5 time	1 time	<.001
	Frequency of cooking at home per week	9.5 times	10.5 times	<.001
	Consumption frequency of sugary drinks per week	3.5 times	3.6 times	.037
	Consumption frequency of fast food per week	0.4 time	0.4 time	.94
	Consumption frequency of fruits per week	8.5 times	8.6 times	<.001
	Consumption frequency of vegetables per week	9.9 times	10 times	.008
Dicken et al 32	High fat, salt, and sugar snacks intake frequency per month	48.3 times	49.2 times	.297
	High fat, salt, and sugar meals intake frequency per month	7.1 times	6.6 times	.007
	Participants consumed few portions of fruits and vegetables per day	70%	67%	.034
Maestre et al 34	Participants ate fruit more than one time per day	66.3%	66.0%	.788
	Participants ate vegetables and salads more than one time per day	41.2%	58.3%	<.001
	Participants ate bread and cereals more than one time per day	85.8%	58%	<.001
	Participants ate red meat more than one time per day	7.9%	13.3%	<.001
	Participants ate fast food more than one time per day	1.1%	0.8%	.233
	Participants ate snacks more than one time per day	1.2%	3.6%	<.001
Sánchez-Sánchez et al 36	Participants with high adherence to the Mediterranean diet	4.7%	8%	<.001
	Participants ate homemade baking	0.3%	4.6%	<.001
Ammar et al 38	Participants consume most of the time unhealthy food	18.4%	23.3%	<.001
	Participants consuming unhealthy food always	6.2%	10.9%	<.001
	Participants have most of the time a snack between meals or late-night	13.9%	24.4%	<.001
	Participants having always a snack between meals or late-night	6.4%	15.4%	<.001

Twelve studies reported a significant change in the frequency of consumption and the proportion of individuals who consumed food groups not recommended for daily consumption.^{7,14,16,23-26,29,30,32,34,38} Nine of them reported changes toward a healthy lifestyle where there was a decrease in the consumption frequency and proportion of people who consumed fast foods, sweet beverages, red meat, snacks, sweet cereals, and ate outside of the home.^{7,14,16,23,26,29,30,32,34} Sidebottom et al ¹⁴ reported that the frequency of people who consumed meals at home increased significantly during the pandemic. These results are supported by 2 other studies.^23,29 Only 2 studies showed a decrease in sweet cereal intake,^32,34 and the other 2 reported a decrease in the frequency of consumption of red meat.^16,26 Bertrand et al ¹⁶ only reported a decrease in sweet beverage intake, snacks, and nuts during the COVID-19 pandemic. On the other hand, 9 out of 12 studies reported changes toward unhealthy lifestyles, such as an increase in the frequency of consumption as well as in the number of people that consumed snacks, sweet beverages, processed meats, nuts, and sweet cereals.^{7,23-26,30,32,34,38}

Ammar et al ³⁸ reported an increase in the proportion of people (13.9%-24.4%) that ate snacks between meals or late at night. These results are supported by 4 other studies that reported an increase in the consumption frequency and in the number of persons that consumed snacks and processed meat during the COVID-19 pandemic.^23,24,32,34 Similarly, Imaz-Aramburu et al ²⁵ reported a rise (68.8%-75.9%) in the percentage of individuals that ate processed red meats daily. These data are similar to the results obtained in the other 2 studies.^26,34

Changes in Physical Activity During the COVID-19 Pandemic

Changes in physical activity were reported in 25 studies (Table 3). We analyzed the changes in PA habits in 2 ways: (a) changes in PA level and time spent doing PA, and b) changes in time spent in sedentary behavior. Almost all the 25 studies that reported physical activity habits showed the same results: there have been changes in physical activity behavior that promoted unhealthy lifestyles during the COVID-19 pandemic, such as a decrease in PA level, less time spent doing PA, and an increase in sedentary behavior. The decrease in PA level is reported in 13 studies: Franco et al ¹⁰ showed a decrease in the proportion of people with low and medium PA in Spain, from 48.8% before to 36% during the pandemic, and similar results are reported in 12 other studies.^{7,11,12,14,16,18,20,24,25,28,35,36} Fifteen studies reported a decrease in people’s time doing PA during the COVID-19 pandemic: Bertrand et al ¹⁶ reported a decrease in time spent in moderate-vigorous PA per week from 85 min before to 65 min during the pandemic; these results are similar to those reported in other 14 studies.^{8,9,15,19,22,26,28-31,33,35,37,38}

Table 3.

Changes in Physical Activity (PA) and Sedentary Habits During the Pandemic of COVID-19 (n = 25).

Articles References	Findings
	Variables evaluated in each study	Before	During	P value
Sultan et al 7	Participants did not exercise	5.3%	19%	<.001
Katewongsa et al 8	Thai adults who meet recommended PA per week	74.6%	54.7%	<.001
	Average time of moderate-vigorous PA per week	580.4 min	420.2 min	<.001
Koohsari et al 9	Total PA time per day	1.7 h	1.5 h	= .01
	Total sitting time per day	8.9 h	9.5 h	<.001
Franco et al 10	Participants had low and medium PA level	48.8%	36%	<.001
	Participants had sedentary behavior	66.7%	83.5%	<.001
Rees-Punia et al 11	Participants met US aerobic PA guidelines	52.5%	43.3%	<.001
	Total sitting time per day	7.5 h	9.2 h	<.001
Skurvydas et al 12	Participants did not exercise	33.3%	36.2%	>.05
Sidebottom et al 14	Frequency of vigorous PA per week	2 days	1 day	<.001
	Frequency of moderate PA per week	4 days	1 day
	Frequency of light PA per week	4 days	2 days
	Total sitting time per day	4 h	7 h	<.001
Alarcón Meza and Hall-López 15	MET-minutes per week	6473 min	4297 min	.005
Bertrand et al 16	Participants met the guidelines of 150 min of MVPA per week	16%	9.6%	<.001
	The time spent in MVPA per week	85 min	65 min	<.001
	Participants met adults’ guidelines for SB (≤8 h per day)	54%	30%	<.001
	The time spent in SB per day	8.3 h	11 h	<.001
Helbach and Stahlmann 18	The frequency of PA per week is at least 30 min once	3.7 days	3.6 days	>.05
	Participants met PA recommendations according to the WHO guidelines	37.4%	36.7%	>.05
Schuch et al 19	Time spent on MVPA per day	107.8 min	43.4 min	<.001
	Time spent on sedentary behavior per day	6 h	8.5 h	<.001
Roggio et al 20	Participants did not do PA (0 min/week)	19.9%	30.6%	<.001
	Participants did light PA (<140 min/week)	30.1%	48.1%
	Participants did MPA (>150 min/week)	21.5%	10.9%
	Participants did high PA (>200 min/week)	28.5%	10.5%
Sandell and Saltychev 22	The average MET value used per week	31.6 MET	32.2 MET	.4487
Abdulsalam et al 24	Participants did not do physical activity	31.6%	35.2%	.000
Imaz-Aramburu et al 25	Students did not practice any PA	4.2%	7.2%	.182
Mascherini et al 26	Total MET-minutes per week of participants	1831.6 min	1684.5	<.01
	Time spent on sedentary behaviors per day	7 h 22 min	8 h 49 min	<.001
Wang et al 28	Time spent in MVPA per week	139 min	120 min	= .01
	Participants reaching the PA guidelines	36%	32%	= .01
Chen et al 29	Total exercise time per day	38.6 min	32.1 min	<.001
	Total screen time per day	5.1 h	6.7 h	<.001
Wang et al 30	Time spent in high-intensive PA per week	155.4 min	102.2 min	<.001
	Time spent in MPA per week	137.6 min	108.5 min	<.001
	Time spent walking per week	328.1 min	236.4 min	<.001
	Time spent sitting or lying per week	1410.0 min	1897.8 min	<.001
Elvén et al 31	Total METs - minutes per week of participants	2400 min	1960 min	<.001
	Vigorous PA MET minutes per week	480 min	32 min	<.001
	Moderate PA MET minutes per week	480 min	240 min	<.001
	Time spent in sedentary behavior per week	2520 min	3150 min	<.001
Rodríguez-Larrad et al 33	Time spent in VPA per week	327 min	267 min	<.001
	Time spent in MPA per week	376 min	265 min	<.001
	Time spent walking per week	766 min	120 min	<.001
	Time spent in sedentary behavior per day	357 min	545 min	<.001
Kontsevaya et al 35	Time spent in MPA per day	42.4 min	30.4 min	<.001
	Time spent in VPA per day	37.79 min	26.56 min	<.001
	Time spent walking per day	60.5 min	40.83 min	<.001
	Participants meet PA Guidelines	67.6%	48.8%	<.001
Sánchez-Sánchez et al 36	Participants that did not practice exercise	28.8%	29.4%	.004
	Participants spent more than 1 h doing exercise	26.6%	14.7%	<.001
Gallè et al 37	Total time spent in PA per week	520 min	270 min	< .05
	Total time spent in sedentary behavior per day	240 min	480 min	< .05
Ammar et al 38	Frequency of PA per week	5 days	3.8 days	<.001
	Time spent in PA per week	108 min	71.8 min	<.001
	Time spent sitting per day	5.3 h	8.4 h	<.001

Note. MET = Metabolic Equivalent of Task, MVPA: Moderate to Vigorous Physical Activity, MPA: Moderate physical activity, VPA: Vigorous physical activity.

The increase in time that people spent on sedentary behavior was reported in 13 studies.^{9-11,14,16,19,26,29-31,33,37,38} Rees-Punia et al ¹¹ found an increase in the time that people spent sitting per day from 7.46 to 9.19 h before and during the pandemic, respectively. Similar results are reported in the other 12 studies.

Changes in Alcohol Consumption During the Pandemic of COVID-19

Seven studies included in this review were related to alcohol consumption before and during the pandemic (Table 4). Five of them^{12,14,17,21,22} reported changes to promote healthy lifestyles where there was an increase in people who did not drink alcohol during the pandemic, as well as a decrease in the frequency of alcohol consumption per week and average drinks per day. Skurvydas et al ¹² reported an increase in people who did not drink alcohol in Lithuania from 14.5% before to 16.6% during the pandemic. On the other hand, only 2 out of 7 studies reported changes toward an unhealthy lifestyle where there was an increase in people exceeding alcohol drink limits, as well as an increase in the alcohol consumption frequency per week during the pandemic of COVID-19.^27,29 Barbosa et al ²⁷ reported in their study an increase in people who exceeded drinking limits from 30.11% before to 36.11% during the pandemic. Similarly, Chen et al ²⁹ reported an increase in the consumption frequency of alcohol from 3.01 to 4.24 times per week, during the pandemic in the USA.

Table 4.

Changes in Alcohol Consumption Habits During the Pandemic of COVID-19 (n = 7).

Articles references	Findings
	Variables evaluated in each study	Before	During	P value
Skurvydas et al 12	Participants did not drink alcohol at all	14.5%	16.6%	>.05
Sidebottom et al 14	Consumption frequency of alcohol per week	once	Less once	.001
Rao et al 17	Participants did not drink alcohol	4%	9%	>.05
Callinan et al 21	Average consumption of drinks per day	3.53 drinks	3.52 drinks	>.05
Sandell and Saltychev 22	Average consumption of alcohol per week	60 g	24 g	<.001
Barbosa et al 27	The average number of drinks per drinking day	2.47 drinks	2.72 drinks	>.001
	Participants exceeded drinking limits	30.1%	36.1%	>.001
Chen et al 29	Frequency consumption of alcohol per week among drinkers	3 days	4.2 days	<.001

Tobacco Use Changes During the COVID-19 Pandemic

In this review, we found only 3 studies^7,13,29 that estimated tobacco use before and during the pandemic (Table 5). Two of them reported changes to promote a healthy lifestyle where there was a decrease in people who smoked and a decrease in the number of cigarettes used before versus during the pandemic. Sultan et al ⁷ in their study in Saudi Arabia, reported a decline in people who smoked from 18.3% before to 15.7% during the pandemic. Similarly, Yang and Ma ¹³ in their study in China reported a decrease in the number of cigarettes smoked per day from 11.02 before to 2.25 during the pandemic. Only one study from the United States of America reported a slight increase in the proportion of individuals who increased their smoking frequency per day, from 9.28% before to 9.8% during the pandemic. ²⁹

Table 5.

Changes in Tobacco use Habits During the Pandemic of COVID-19 (n = 3).

Articles references	Findings
	Variables evaluated in each study	Before	During	P value
Sultan et al 7	Participants smoke	18.3%	15.7%	.049
Yang and Ma 13	Cigarettes smoked per day	11	2.2	<.001
Chen et al 29	Cigarettes smoked per day	9.3	9.8	<.001

Discussion

This study aimed to systematically review the changes in diet, PA, alcohol consumption, and tobacco use habits before and during the COVID-19 pandemic in adults. The overall quality of studies in the present review is moderate. In general, we found changes in lifestyle habits during the COVID-19 pandemic that may promote healthy and unhealthy lifestyles.

Regarding the changes in dietary habits during the pandemic, we found an increase in the intake of food groups recommended for daily consumption, such as legumes, vegetables, fruits, and water, as well as the Mediterranean diet in most countries. These changes can be explained by an increase in the time people spent at home to prevent COVID-19 propagation. Therefore, people had more time to buy, cook, and eat a healthy diet, which can increase the consumption of fresh and accessible food. ⁴² Also, there was a decrease in the consumption of food groups not recommended for daily consumption, like high-calorie-rich foods such as fast food; this decrease could be due to the closing of most fast-food restaurants during the pandemic. ⁴⁴ On the other hand, we found a decrease in the consumption of food groups recommended for daily consumption and an increase in the consumption of food groups not recommended for daily consumption (snacks, sweet beverages, and cereals). This behavior can be explained by the time that individuals spent at home during the pandemic watching movies or doing other sedentary activities. The increase in high-calorie food intake is associated with overweight and obesity, as well as with other chronic diseases.^40,41 De Luis Roman et al ⁴³ reported an increase in body weight in people who raised their consumption of snacks compared to people who did not consume snacks during the 7 weeks of the COVID-19 pandemic in Spain.

Regarding physical activity behavior, we found that during the COVID-19 pandemic, the physical activity level and time people spend doing PA decreased, and sedentary behavior increased in most parts of the world. These changes were due to different COVID-19 prevention measures implemented, especially confinement, which may be associated with stress, anxiety, and depression. These mental health problems could also impact eating behavior, which was associated with elevated intake of high-calorie foods and consumption of alcohol and tobacco.^3-5 Physical inactivity and an unhealthy diet were also reported to be associated with weight gain, overweight, obesity, and non-communicable diseases. ⁴⁵ De Luis Roman et al ⁴³ reported an increase in body weight in people who did not perform physical activity compared to people who performed regular PA during the pandemic in Spain.

Changes in alcohol consumption habits during the COVID-19 pandemic were positive in most countries, where there was a decrease in the quantity and frequency of alcohol consumption, except in the United States of America. Social distancing and home isolation could explain these findings and also the possible economic consequences. ⁴⁶ However, more research is needed in different countries to confirm this hypothesis, as there are only a small number of studies on alcohol consumption before and during the COVID-19 pandemic. The increase in alcohol consumption in the USA can be explained by the rise in alcohol sales by more than 20% during the COVID-19 pandemic in the country.^54,55,56

Regarding tobacco use habits during the COVID-19 pandemic, the results show a decrease in the number of people who smoked, the number of cigarettes, and the frequency per day. This decrease may be related to the knowledge that people received from communication media, and also due to economic consequences.^46,47 More research is required to know the smoking situation in many countries and the reason behind it, as there are only 3 studies in this review about tobacco use. Thus, this smoking reduction may have a positive health impact not only for those who reduced or stop smoking but also for those who are exposed to secondhand smoke.

Generally, the results in this study show changes in diet, physical activity, alcohol consumption, and tobacco use before/during the COVID-19 pandemic that may promote healthy or unhealthy lifestyles. This information may help public health directors and staff to develop strategies that could prevent the health consequences that changes in lifestyle due to COVID-19 or future pandemics can cause in physical and mental health status in the short, medium, and long-term periods.

Limitations and Strengths of the Study

One limitation is that most studies included in this review were cross-sectional and used online self-reported data, which can lead to misreporting or underreporting. In most of the studies, the people who participated before and during the pandemic were not the same, and the sampling technique was not random. Therefore, the risk of bias, such as sampling bias and self-reporting bias in each study included in this review was high, so the results are difficult to generalize. The other limitation is that only 2 databases were used in this review. As a strength, this review focused on the analysis of 4 lifestyle habit changes during the COVID-19 pandemic. The study not only shows changes that promote unhealthy lifestyles but also shows changes toward a healthy lifestyle. The evidence included in this review is from before and during the pandemic. Another strength is that peer-reviewed articles in English, French, and Spanish were included and came from all over the world.

Conclusion

We found changes before versus during the COVID-19 pandemic, which promote healthy lifestyles, such as an increase in the consumption of the Mediterranean diet, vegetables, and fruits, and a decrease in the consumption of fast foods. Also, an increase in the consumption of homemade diets and a decrease in alcohol intake and tobacco use in most countries. On the other hand, there was an increase in the consumption of processed red meat and caloric-rich food products, a decrease in physical activity, and an increase in sedentary behavior, related to unhealthy behavior. The latter may affect people’s mental and physical health in the short and long term. Emergency responses are needed to mitigate the consequences of an unhealthy lifestyle.