1. Introduction
The COVID-19 pandemic required an extraordinarily rapid process of adaptation for both individuals and governments. Since the detection of the first cases, the World Health Organization has estimated that more than 1.1 billion people worldwide have contracted the disease and over 6.9 million have died as a result, although these figures may be underestimated due to variations in testing strategies, reporting criteria, and delays in surveillance systems [
1]. The sheer scale and speed of the pandemic forced countries to implement unprecedented containment measures. In Spain, strict home confinement became a central strategy to slow transmission, leading to profound and immediate changes in daily routines, mobility, and lifestyle behaviors.
Given the rapid transmission of COVID-19 and the difficulties in preventing and treating this type of virus, strict containment measures were adopted in Spain to curb its spread, transforming the lives of citizens in many ways. Although confinement proved effective during the first wave of the pandemic, people’s response to such a stressful and prolonged situation has been linked to multiple physical and psychological consequences, such as increased levels of stress and anxiety [
2,
3]. Likewise, it appears to have modified lifestyle and daily eating habits, which led various organizations to recommend maintaining a healthy diet during confinement [
4,
5]. This change in eating habits as a consequence of confinement has been observed in adult populations in various countries [
6,
7], due in part to overeating, which led to weight gain [
8,
9], especially among those who were previously obese [
10,
11], who seem to show hypersensitivity to non-nutritive cues and desensitization to normal satiety processes [
12].
A growing body of international research has shown that lockdown periods significantly affected dietary patterns and body weight across diverse populations. Studies conducted in Italy, Denmark, Poland, Tunisia, and the United States reported declines in diet quality, higher consumption of ultra-processed foods and snacks, greater snacking frequency, and alterations in meal timing during confinement [
8,
9,
11,
13,
14]. These shifts were frequently accompanied by weight gain, particularly among individuals with pre-existing overweight or obesity, who may have been more reactive to external eating cues and less responsive to physiological satiety signals [
6,
10,
15,
16]. Reduced opportunities for physical activity, increased sedentary time, and disruptions in food access likely contributed to this pattern.
In addition to dietary changes, sociodemographic and psychological factors appear to have shaped the impact of lockdowns across countries. Younger adults tended to experience more substantial alterations in their eating habits, including irregular meal schedules and increased intake, whereas older adults were more likely to maintain stable routines [
12,
13]. Caregiving duties further intensified these challenges: individuals caring for dependent children reported more disorganized routines, higher stress, and greater changes in food consumption [
17]. At the same time, psychological distress increased sharply worldwide. Systematic reviews identified anxiety levels ranging from 6.3% to 50.9% and depression from 14.6% to 48.3% [
18], while a large meta-analysis reported combined prevalences of 28% for anxiety, 27% for stress, 22% for depression, and 33% for post-traumatic stress symptoms [
19]. Stress- and anxiety-related eating—characterized by increased intake of palatable, carbohydrate-rich foods—was widely observed [
20,
21,
22].
Given this background, the aim of the present study was threefold: (a) to examine the impact of confinement due to the COVID-19 pandemic on the eating habits of the adult Spanish population—specifically, whether eating habits were modified in general, as well as the nutritional quality and quantity of intake, and whether mealtimes were modified; (b) to analyze the impact of confinement on participants’ weight; and (c) to study which variables were related to possible changes in eating habits during confinement.
4. Discussion
The aim of this study was to examine the impact of confinement due to the COVID-19 pandemic on the eating habits and weight of the adult Spanish population, and to analyze the variables related to possible changes in eating habits during this period.
First, regarding the impact on eating habits, the results reflect a general worsening of the nutritional quality of the diet in the Spanish population during confinement, as observed in other countries [
6], but contrary to findings from another study in Spain based on the consumption of different foods [
23]. There was also a significant increase in food intake during meals, with percentages similar to those found in studies conducted in other countries [
9,
11,
13,
14], perhaps due to the increased practice of snacking between meals detected during confinement [
11]. In addition, there was a greater tendency to store food, especially canned and ultra-processed products, due to their ease of storage and preparation [
16]. This may partly explain the changes in the quality and quantity of intake detected, although a study suggests that variables such as sex, age, and changes in income are associated with higher consumption of sugary drinks and fast foods during the COVID-19 pandemic [
24].
Second, with regard to the impact on weight, the results indicate that the modifications in eating behavior observed during confinement translated into a noticeable increase in body weight in a substantial proportion of participants, a pattern consistent with findings reported in studies conducted during the same period [
8,
25]. This agreement with previous research reinforces the idea that prolonged restrictions on mobility and changes in daily structure tend to generate similar behavioral responses across different populations. The increase in weight may not only reflect the rise in intake observed in the sample but also the reduction in opportunities for physical activity resulting from staying at home, the closure of public spaces and sports facilities, and the difficulty in maintaining pre-pandemic routines [
16,
26,
27]. Such disruptions have been widely associated with a progressive decline in energy expenditure and a greater likelihood of weight gain [
20,
22,
25,
28]. In addition, confinement may have intensified sedentary behaviors —including increased screen time, teleworking, and prolonged indoor stays— which previous research has linked to adverse metabolic consequences and higher susceptibility to weight gain. Psychological factors may also have contributed: heightened stress, uncertainty, and emotional vulnerability during the pandemic are known to influence appetite regulation, preference for high-calorie foods, and the frequency of snacking.
Taken together, these findings suggest that the observed weight increase was likely the result of an interaction between dietary changes, reduced physical activity, emotional responses, and environmental constraints inherent to lockdown conditions. This multifactorial explanation highlights the importance of integrated public health strategies that simultaneously address eating behaviors and physical activity during future scenarios involving prolonged restrictions.
Third, in relation to variables associated with changes in eating habits and weight, several sociodemographic and personal factors were identified. As in other populations [
7], the youngest participants—those under 35 years of age—were the ones whose overall eating habits worsened and whose mealtimes changed to a greater extent, although the quality of their diet improved, perhaps due to the greater adherence to the Mediterranean diet observed in this age group in other countries [
8]. Likewise, their intake and weight were reduced to a greater extent than in other age groups. In contrast, older participants were those who maintained all the eating habits analyzed to a greater extent, showing a lesser impact of confinement on their diet, although those over 36 years of age experienced greater weight gain, as reported in other studies [
11]. Although the overall trend was toward a decline in dietary quality, there are distinct profiles whose eating habits were able to improve due to specific protective conditions during confinement, such as increased time available to plan and cook, heightened health awareness, more structured family routines, and greater control over the food environment [
8,
11].
In relation to BMI, obese participants worsened their eating habits during confinement to a greater extent than the other groups, as found in other studies in the Spanish population [
21]. They also increased their intake and modified their mealtimes more markedly, followed by overweight participants. Consequently, these groups showed the greatest increase in weight, consistent with previous findings [
10,
11].
Emotional factors were also relevant. As expected from the literature, participants who experienced nervousness or anxiety during confinement saw their eating habits worsen and their weight increase to a greater extent, in line with studies linking higher intake with greater anxiety during this period [
29]. Numerous studies have corroborated how emotions influence eating behavior [
21,
30]; indeed, psychosocial stress appears to affect body weight through biological, behavioral, and psychological mechanisms [
31,
32]. In particular, stress- or anxiety-induced eating can lead to increased food intake —especially of palatable, high-glycemic foods—as well as more frequent snacking [
20,
22,
28], a pattern observed in various populations during the pandemic [
16,
33,
34]. Similarly, studies conducted with individuals with eating disorders show that patients with restrictive eating disorders exhibited poorer family functioning and greater eating psychopathology after the pandemic compared to previous periods, although results differed by age and diagnosis [
35,
36]. Overall, anxiety appears to function as a vulnerability factor that shapes dietary responses in situations of prolonged stress.
Having experienced symptoms compatible with COVID-19 during confinement also seems to have influenced eating habits and weight, as those who reported symptoms were more likely to improve their eating habits and the nutritional quality of their intake, and to lose weight. This could be related to the gastrointestinal symptoms associated with the disease [
37] and the specific diets recommended to address them. The only differences between those who lived with someone with COVID-19 symptoms and those who did not were related to weight, which was reduced in the former and maintained or increased in the latter, possibly because those living with symptomatic individuals may also have contracted the disease.
Likewise, participants who had children in their care during confinement—a situation likely to increase stress, especially when combined with teleworking—reported greater deterioration in their eating habits, including increased intake, later mealtimes, and irregular schedules, which may have contributed to weight gain [
17]. By contrast, those without childcare responsibilities maintained or even improved their eating habits and weight status. Furthermore, anxiety experienced during the confinement period was significantly associated with poorer dietary quality, particularly among individuals with low physical activity, supporting the idea that emotional distress and caretaking burden can combine to worsen eating behaviors [
38].
Work circumstances also impacted eating habits and weight. Participants who continued working outside the home and were able to preserve pre-pandemic daily routines tended to exhibit better overall eating habits and higher nutritional quality of the diet, suggesting that structured schedules and external time cues may help to maintain more stable lifestyle patterns. However, in our sample, this more favorable profile coexisted with an increase in intake, which could be partly explained by stress related to the risk of contagion outside the home and longer or more demanding workdays. Recent studies have shown that changes in work arrangements during the pandemic, including working from home, were associated with both perceived improvements in diet and, paradoxically, higher caloric intake, weight gain, and diet-related health problems, largely mediated by increased sedentary time and psychological strain [
39,
40].
This study allowed us to explore the impact of COVID-19 confinement on eating habits and body weight in the Spanish adult population. It also examined the sociodemographic and personal factors that may have influenced the differential effects of confinement, some of which had not been studied previously. The results are consistent with previous research on the impact of lockdown on eating habits, which has been associated with mental health, gender, and socioeconomic status [
24].
These findings support the development of prevention strategies for future prolonged confinements or periods of high stress. Public health campaigns should specifically promote healthy eating among populations most affected by confinement, discouraging overeating and informing about the risks of excessive consumption of hypercaloric foods during periods of reduced physical activity and challenges in weight management [
14]. Overall, these results underscore the importance of implementing social and communication strategies that promote healthy eating, particularly during health emergency scenarios [
14,
24].
Among the limitations of the present study are a possible social desirability bias and recall bias related to health habits. These were partly mitigated by requesting anonymous participation and using objective measures, such as body weight assessed with a scale. Although the data reflect participants’ subjective experiences, these perceptions are valuable because they influence self-assessed quality of life and, consequently, the promotion or maintenance of healthy habits. The use of a convenience sample limits the generalizability of the results to the Spanish population, and international comparisons must consider cultural and contextual factors. Additionally, the sample included a disproportionately higher number of women and participants with overweight or obesity, which may limit the applicability of findings to more gender-balanced or weight-diverse populations. The cross-sectional design of the study does not allow causal inferences or the assessment of the temporal stability of the observed changes. Future research should employ longitudinal designs to evaluate whether dietary changes during confinement are maintained, intensified, or reversed over time. Data collection was conducted online and relied on retrospective self-reports, potentially introducing recall bias and affecting the accuracy of the information. Furthermore, the ad hoc questionnaire included data on anxiety status without using a validated measure, which may reduce the reliability of anxiety-related results. Finally, this study did not examine the effects of socioeconomic variables such as education, income, and employment status, which can influence eating habits, access to healthy food, and stress management during lockdown. As the study focused on demographic, psychological, and contextual variables, future research should incorporate socioeconomic variables to explore their modulating role in the relationship between stress, diet, and weight changes in crisis situations.
5. Conclusions
Strict COVID-19 confinement in Spain was associated with a general worsening of eating habits, particularly an increase in food intake and a consequent rise in weight among a considerable proportion of the population. The findings indicate that certain demographic and personal characteristics acted as risk factors for these changes, particularly being female, being under 35 years of age, being overweight or obese, caring for dependent children, and experiencing nervousness or anxiety during this period. In contrast, protective variables that favored the maintenance of pre-confinement habits included being male, being 50 years of age or older, having a normal or low weight, working outside the home, and not having dependent minors. These results underscore the heterogeneity of responses to confinement and highlight how specific circumstances modulated its impact on diet, routines, and weight.
Based on these results, several avenues for future research can be proposed. First, longitudinal studies are needed to determine whether the changes observed during confinement were temporary or whether they persisted once mobility restrictions were lifted. Such studies could clarify the temporal stability of the dietary patterns identified and help determine the factors that predict their maintenance or reversal. Second, it would be useful to incorporate validated instruments to assess psychological variables—particularly anxiety and stress—to more precisely determine their relationship with eating behaviors and weight trajectories during prolonged stress situations. Third, future research should include socioeconomic factors such as education level, income, and employment conditions to better understand how inequalities shape access to healthy foods, the ability to maintain routines, and the adoption of coping strategies during crises.
More detailed analyses of family composition, work arrangements, and the interaction between caretaking responsibilities and psychological strain could also provide a better understanding of which subgroups are most vulnerable to lifestyle deterioration during lockdowns. Finally, experimental and intervention studies could help design and evaluate targeted strategies aimed at preventing overeating and weight gain during periods of reduced mobility, particularly in those groups identified as being at higher risk. Taken together, the present findings reinforce the need to develop prevention plans for future health emergencies that integrate nutritional, psychological, and social components, with special attention to the populations most affected by confinement.