Consequences of Quarantine During the COVID-19 Pandemic on Food Intake and Body Weight: A Systematic Review

Background: Due to the coronavirus disease (COVID-19) pandemic, some authorities have implemented measures to control the spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), such as quarantine. The aim of this systematic review was to summarize the results of the studies that investigated changes in eating habits, food intake, and body weight during the COVID-19 quarantine. Methods: This review followed the recommendations of the PRISMA protocol and has registration in the PROSPERO under number CRD42020212491. Searches used databases PubMed, Medline, Scielo, and Lilacs. Two authors conducted the selection process blindly and independently using the Rayyan software (QCRI). Of 5,248 papers, we included 28 studies. Results: Most of the included studies in this review presented data on changes in food intake (n = 22). These changes were especially towards the adoption of unhealthy eating habits such as an increase in the consumption of snacks and sweets; and a decrease in the intake of vegetables, fruits, fish, and dairy products (n = 21). Concerning body weight, the main change was towards weight gain (1.5 to 4.5 kg), which was positively associated with age (elderly); socioeconomic level (average socioeconomic level); increase of the intake of snacks, sweets, fried foods, and fast foods; and low consumption of vegetables. Besides, weight gain was inversely associated with physical activity and positively associated with sedentary time (n = 14). Conclusion: In this sense, the summarized evidence points to a change in eating habits, food intake, and body weight, as well as a relevant association between unhealthy eating choices and weight gain during quarantine. The COVID-19 quarantine caused an interruption in the routine of daily life, which generated an impact on mental health,


Introduction
In December 2019, an unknown disease first identified in Wuhan, Hubei, China, named as 2019-nCoV and later renamed COVID-19 by the World Health Organization (WHO), warned the medical and scientific communities (1,2). This disease quickly spread in several countries and on 11 March 2020 was declared as a pandemic by the WHO (3). The statistical data of the COVID-19 of July 2021 show that more than 184 million people already were infected and more than 3,9 million died worldwide (4). Its symptoms range from those most common such as cough and fever to those more severe such as shortness of breath, and other uncommon ones, such as loss of taste and smell (5).
The COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that spreads from person to person through droplets generated by coughing, sneezing, and talking. Containment strategies in the face of the growing number of cases revolve around social distancing, quarantine, and public places' closure. Despite the benefits provided by such strategies in combating the spread of the virus, these measures can favor the occurrence of adverse health effects, especially because they can cause an interruption in the practice of physical activity, an increase of the risk of anxiety and boredom due to social isolation, as well as can negatively affect food choices. (3,(6)(7)(8)(9).
Quarantine is describing as a measure to isolate those who have contact with an infectious disease and, subsequently, to prevent its spread. There is also the reverse quarantine, a measure that isolates those belonging to the greatest risk of contracting the disease. These measures differ from isolation, a measure of distance from those affected by the infectious disease during the disease incubation period (10).
The lifestyle has undergone many changes in the face of COVID-19 quarantine, with emphasis on the increase of food consumption, decreased physical activity, increased sedentary time, excessive screen time, and poor sleep quality (11)(12)(13). These changes can have been generated by the psychological and restrictive impact caused by this measure. The quarantine can have a direct impact on mental health, especially on the development of anxiety, distress, a feeling of loss of control, loneliness, depressive symptoms, and post-traumatic stress disorder (14). All these feelings contribute to the worsening of the quality of food, with an increased risk of developing "emotional eating" and weight gain (15).
Although the WHO published that good nutrition is crucial for health, particularly when the immune system might need to fight back (16), changes in food intake and eating habits during COVID-19 quarantine may not be in line with the recommendation. Some studies have demonstrated that COVID-19 quarantine contributed to increased intake of energy, sodium, and fat; and decreased fruits and vegetables consumption (3,6,17). These negative changes in dietary patterns may result in weight gain, activation of the innate immune system and inhibition of the adaptive, increase in the production of inflammatory mediators, and other factors that can influence COVID-19 (17,18). On the other hand, healthy dietary patterns including a high intake of fruits and vegetables and low consumption of sugar and saturated fats can prevent chronic diseases and improve related-chronic low-grade inflammation (19)(20)(21).
In addition to changes in food intake, some studies also have shown that during COVID-19 quarantine there was a change in body weight, especially towards to increase of the self-reported weight (22,23). Excessive weight gain can lead to obesity that is increased worldwide and characterized by an increase of body fat (24) and low-grade inflammation, which is a recognized link between obesity and other chronic diseases (25,26).
Emerging evidence shows that obesity can be a risk factor for poor outcomes by COVID-19 and still a predictor of mortality (27)(28)(29). This occurrence can potentiate the aggravating factors of COVID-19 due to the increase of pro-inflammatory adipokines that contribute to establishing inflammation and oxidative stress. Moreover, obesity seems to impact lung function and immune responses (30,31). Besides, obesity is associated with some comorbidities, such as hypertension and diabetes, which also have been considered risk factors for complications of the COVID-19 (32). However, it's important to emphasize that there are other factors important that influence the mortality by COVID-19, such as age, e.g. elderly individuals are more likely the complications and mortality when compared with younger individuals (33).
In this sense, the aim of the present systematic review was to compile the studies that investigated changes in eating habits, food intake, and body weight during the COVID-19 quarantine. We summarize the main changes in eating habits, food intake, and body weight resulting from quarantine, as well as the factors that impacted these changes. In addition, we investigate whether changes in the food intake were associated with the change in weight body.

Methods
This is a systematic review guided by the following question: What are the Two authors (PMP and NMCO) independently made the paper selection using the Rayyan QCRI website, the Systematic Reviews web app. This selection is according to a protocol previously established by the authors, where authors selected the articles by reading the titles and abstracts and later by reading them in full. The inclusion criteria were original articles, published in English, Portuguese or Spanish, conducted with adolescents, adults, and elderly individuals with or without underlying diseases, and in whose paper the main objective was to assess the influence of quarantine on changing food intake and/or body weight. The exclusion criteria were reviews, studies conducted with children, original studies conducted with animals, and those that did not obtain relevant information to clarify the guiding question. These criteria were adopted so that the objectives previously established were achieved ( Table 1).
The following data were extracted and compiled independently by 2 authors (PMP and NMCO): first author, year of publication, country, study design, sample, sample size, objectives, and outcomes concerning changes in food intake and body weight. The data are in alphabetical order followed by the name of the first author of the study.
Two authors (PMP and NMCO) also evaluated the article's methodological quality. The cross-sectional studies were assessed using a checklist with questions focused on cross-sectional studies, Checklist for analytical cross-sectional studies, Joana Briggs Institute (34). Then, the same authors classified articles as low (<50%), moderate (50-70%), and high quality (> 70%), according to the degree of contemplation of criteria related to the clarity of the inclusion of individuals in the study, description of the scenario, the measurement made validly and reliably. The observational and longitudinal studies were assessed by the tool for assessing Risk of bias in nonrandomized studies of interventions (ROBINS-I). The authors classified the articles as moderate or low risk, according to the domains specified in ROBINS-I, which include (1) bias due to confounding, (2) bias in the selection of participants into the study, (3) bias in classification of interventions, (4) bias due to deviations from intended interventions (5) bias due to missing data, (6) bias in the measurement of outcomes, (7) bias in the selection of the reported result and (8) overall risk of bias (35).

Selected Studies
The search identified 5,248 articles. Of these, 28 articles composed this review.
The adoption of healthy eating habits reported by some studies (n = 11) it concerns the increased consumption of fruits, vegetables, fish, dairy products, grains, water, and decreased consumption of fast food, sweets, sweet drinks, and ready-made foods. The consumption of fruits and vegetables increased by up to 37% and 43%, respectively, fish and dairy products by 30%, grain by 37%, and water by 3.7%, while reduction in fast food consumption went from 44.6% to 64%, ready-to-eat foods in 2%, sweet foods in 50% and sweet drinks in 30% during quarantine (2,17,18,22,36,39,42,44,46-50,53-55) ( Table 2).
Some studies have found changes in alcohol intake (n = 7), with a decrease during quarantine by up to 57.3%, and an increased by up to 18.3% (17,22,36,39,46,55,58). Some articles evaluated factors that impacted food intake. The reported factors were boredom/solitude by 36% and anxiety/depression by 34.7% of those who participated in one study (44); eating in response to the sight and smell of food by 65%, eating when stressed by 52%, anxious by 41%, and bored by 73% of the respondents in another study (52); and the increased mental stress in a third study (48). The study of Zachary et al. (52) found that a large increase in eating in response to stress is one of the risk factors for weight gain, ranging from 5 to 10 pounds and the study of Huber et al. (48) found that mental stress was associated with increased of the amount of food during quarantine.  (Table 3). Weight loss was reported by a smaller portion of 4% to 31.1% and with an average loss greater than 4.5 kg, with the reported weight maintenance being up to 68.5% of respondents (36, 52,53).

Quality Assessment of Articles
The articles included obtained a positive evaluation in general, and all obtained a positive evaluation, none of the criteria related to the analysis performed (n = 25),

Discussion
To our knowledge, this is the first systematic review that compiled evidence about the influence of COVID-19 quarantine on changes in food intake, body weight, and its inter-relationship. In this sense, eating habits were healthier or unhealthier than those observed before quarantine, which was related to body weight changes (Figure 2).
The adoption of healthy eating habits found in this review may be an essential strategy for strengthening the immune system, in order to improve response to infections (59). The Food and Agriculture Organization of the United Nations (FAO) recommends that during the COVID-19 pandemic, people adopt a healthy diet to support the immune system functions. In this sense, this agency recommendations the consumption of a diet rich in fruits, vegetables, whole grains, nuts, and healthy fats such as oils rich in unsaturated fatty acids; a limited intake of foods with high amounts of fats, sugar, and salt; a regular water consumption; and limited alcohol consumption (60).
The immunological system is active full-time, thereby, when pathogens agents, such as the SARS-CoV-2, infect a human cell, innate and adaptive immune response, as well events mediated by the complement system may be a trigger to control the infection and eliminate the pathogen. In this perspective, the induction of an adequate host immune response can protect the organism against more severe complications of diseases such as COVID-19. On the other hand, if the generated immune response is insufficient, may occur, for example, increased viral replication, resulting in tissue damage (61). Several nutrients are involved with the adequate immune response, thus, the adoption of a healthy diet is important for the adequate supply of these nutrients (62).
Considering this context of immunity, the increased consumption of fruits, vegetables, fish, and dairy products found in this review was beneficial. For example, fruits and vegetables contain micronutrients that act on the adaptive immune system, production of antibodies, anti-inflammatory regulation through antimicrobial activity, among other aspects of combating viral infections (63,64). Interestingly, Hermsdorff et al. (25) showed that higher consumption of fruits and vegetables was associated with a lower mRNA expression in peripheral blood mononuclear cells (PMBC) of certain proinflammatory markers, including the transcription of nuclear factor-κB (NF-κB). In addition to essential vitamins and minerals, fruits and vegetables are also important sources of antioxidants, which allow the maintenance of immune cell function, through protection against oxidative stress (19,(65)(66)(67).
In turn, fish contains unsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) that prevent lung damage, mainly through antiinflammatory pathways (63). The anti-inflammatory activity of these essential fatty acids can reduce the eicosanoids formation, which has pro-inflammatory characteristics, derived from arachidonic acid metabolism (68). On the other hand, dairy products could influence the immune system response to COVID-19 through vitamin D, which reduces the risk of viral infections through physical barriers and natural immunity and induction of the innate immune system (64,69).
Therefore, the evidence with animal models and human studies indicates that specific nutrients participate in the differentiation and maturation of immune cells; guarantees the integrity of physical, chemical, and biological resistant barriers; increases the activity of natural killer cells and T lymphocytes; improves the production of antibodies and favors the phagocytosis process (62). In this sense, the consumption of a diversified and varied diet, as recommended by the healthy eating guidelines, is essential to support the immune system's functioning. Furthermore, considering the benefits of these foods, especially for the immune system, governments must reinforce the food guides and food and nutrition policies to guarantee healthier food choices in a pandemic situation such as COVID-19. In relation to alcohol consumption, some studies reported a decrease in the intake of alcoholic beverages (17,22,39,55,58), while others showed an increased (22,36,46). In the COVID-19 pandemic, the excess consumption of alcohol, 20-40 and 30-60g / day for women and men respectively, could increase the risk of infections, promotes apoptosis of T cells, increases symptoms of bronchitis, in addition to being a risk factor for pneumonia (78,79).
In this review, we observe that emotional factors impacted the food choices and eating behavior during COVID-19 quarantine. Being bored contributed to eating unhealthier and for increased food intake, anxiety/depression influenced the eating habits, and the increased mental stress led to changes in food amount (44, 48,49,52).
Quarantine is associated with interruption of the routine, which could result in boredom.
Besides, continuously hearing or reading about the COVID-19 pandemic can lead to stress. Boredom has been associated with high consumption of protein, fats, carbohydrates, and energy, while stress can contribute to the greater desire for specific foods, known as "food craving" (1). Ruiz-Roso et al. (2) evaluated this desire for food in your study and showed that the increased consumption of snacks, vegetables, and dairy products significantly related to food cravings among the study population during the lockdown.
Regarding changes in body weight during COVID-19 quarantine, most studies revealed an increase in self-reported body weight and a greater perception of weight gain. This weight gain observed during the quarantine was associated with mood changes; psychological stress; increased consumption of sweets, sugary beverages, alcohol, and homemade pastries; consumption of fried foods and junk food ≥ 3 times / showed that overweight and obesity were independent risk factors of severe COVID-19 (81). Another study with 770 adult patients with COVID-19 demonstrated that obesity was associated with a significantly higher rate of intensive care unit (ICU) admission or death (27). In addition, a prospective cohort study including 5,795 adults and elderly hospitalized with COVID-19 found that mortality was significantly major in higher body mass index (BMI) (82). Studies have also been associating diabetes with the severity of SARS-CoV-2 infection and mortality by COVID-19 (83,84).
Obesity contributes to establishing a low-grade chronic inflammation. The exacerbated release of cytokines such as interleukin-8 and tumor necrosis factor can aggravate lung parenchyma injury. Moreover, this situation influences the development of several disorders such as insulin resistance and oxidative stress, which also lead to a greater propensity to infections, therefore, it has direct impacts on the worsening of the disease in question (32,81,85).
Finally, in this review was observed that individuals with overweight and obesity were more likely to show negative changes in food intake and weight body during quarantine when compared to individuals with normal weight. Thus, high BMI was correlated with a greater desire for food, eat unhealthier, eat more than usual, lower diet quality, and weight gain (2,22,49,56). In addition, individuals with depression were 49% more likely to elevated frequency of ultra-processed foods consumption incidence when compared with individuals without depression (57). Those findings show that individuals with overweight, obesity, and depression during adverse situations, such as quarantine can need more support and encouragement to maintain or adopt healthy habits. Moreover, it was noticed that studies carried out at the beginning of the quarantine period already pointed to a significant change in food intake and body weight. Thereby, it is suggested that quarantine was able to quickly promote changes in the behavior of the individuals in general (2,18,44,58).
This review has limitations. The selected papers are mostly cross-sectional studies, thus, the outcomes cannot reflect the cause-effect between quarantine and changes in eating habits and body weight. Most of the studies included in this review were online surveys, consequently, participated of the studies individuals who had access to the internet, therefore, the total sample of this review may not reflect the population in general. The data on food intake and body weight were self-reported, however, in our experience, self-reported data showed good reliability (86). The studies included in this review were heterogeneous in terms of methods of assessment of the food consumption, as well as about the study population, that presented demographic characteristics and medical conditions different.
From an epidemiological perspective, the data found in this review are of great importance, since allowed us to observe that quarantine was capable of promoting negative changes in food intake and body weight in different populations. These changes can affect the metabolic control of several chronic diseases and create an overload even bigger for the public health system. Although events that require authorities to adopt quarantine as a restrictive measure are rare, these events can be unexpected and have a variable duration. In this sense, the knowledge of these changes becomes important for authorities to direct public health policies in quarantine situations. Concerning COVID-19, future studies should be conducted to assess the long-term effects of quarantine on food intake, eating habits, and body weight.

Conclusions
The evidence found points to a change in eating habits and body weight during quarantine, mainly towards the adoption of unhealthy habits and weight gain. Some countries may still need to adopt quarantine as a control measure of the COVID-19, in these cases, public policies that encourage healthy lifestyle habits are necessary to prevent the population from changing above all their eating habits and body weight. The adoption of healthy eating habits and the maintenance of weight can be important allies of the vaccine and other treatments of the COVID-19.

Acknowledgments
We

Availability of data and materials
Data sharing does not apply to this article as no datasets were generated or analyzed during the current study.

Competing interests
PMP, NMCO, LCVC, and HHMH, no conflicts of interest.  * Other objectives: studies that did not contribute to the answer to the question raised in this review, those referring to food insecurity in this quarantine period, others that dealt with specific nutrients and not changes in food consumption in a more general way as proposed by this review.

Original articles Published in English, Portuguese or Spanish
Conducted with adolescents, adults, and elderly individuals with or without underlying diseases Whose paper the main objective was to assess the influence of quarantine on changing eating habits and/or body weight

Reviews Studies conducted with children
Original studies with animals Those that did not obtain relevant information to clarify the guiding question  To quantify the impact that COVID-19 quarantine has on behavior associated with weight gain Maintenance of weight (59%), ↑ of weight in 5 to 10 pounds (22%), and ↓ of weight in more than 10 pounds (4%) Individuals who increased the weight reported the highest increase in relation to food, in relation to vision and smell, compared with those who declared that they did not change everything (p = 0.048) Figure 1 Flowchart based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (Moher et al. 2009). * Other objectives: studies that did not contribute to the answer to the question raised in this review, those referring to food insecurity in this quarantine period, others that dealt with speci c nutrients and not changes in food consumption in a more general way as proposed by this review.

Figure 2
Changes in food intake, eating behavior, and body weight during COVID-19 quarantine