Patterns of food preparation

Regarding food preparation patterns, the findings of this study indicate that nearly three-quarters (71.7%) of Portuguese residents eat foods and beverages prepared and/or procured mainly away from home, that is, originating from the foodservice or the food processing and retail sectors rather than prepared at home. Indeed, household expenditure data place the share of away-from-home food spending in Portugal at 10.6% in 2022, well above the European Union average of 6.7%.⁽⁵⁶⁾ Despite Portugal’s disposable income per capita being lower than the European Union average, work schedules, better weather conditions, and cultural preferences for dining out, together with the increasing availability and convenience of foodservice options may contribute to the Portuguese higher spending on food away from home. A comparable analysis of adult food intake data from the United Kingdom National Diet and Nutrition Survey 2008/16 reveals the consumption of food prepared at home to be low.^{(Reference Clifford Astbury, Penney and Adams24)} On the contrary, analyses of adult intakes from the North/South Ireland Food Consumption Survey 1997/99,^{(Reference O’Dwyer, Gibney and Burke37)} the US National Health and Nutrition Examination Surveys 2003/04 and 2007/08,^{(Reference Smith, Ng and Popkin6)} the Republic of Korea National Health and Nutrition Examination Survey 2007/09,^{(Reference Lee, Song and Cho29)} as well as of intakes from the Republic of Ireland National Children’s Food Survey 2003/04,^{(Reference Burke, McCarthy and O’Neill36)} indicate that the consumption of food prepared at home is largely prevalent in these regions. Aside from variation in food preferences and habits attributable to culture, such disparity in extant findings likely stems from underlying methodological differences in the timeframe, sampling, age group, dietary assessment protocol, and food intake classification applied.^{(Reference Bezerra, Curioni and Sichieri57,Reference Wellard-Cole, Davies and Allman-Farinelli58)}

Demographic and socio-economic characteristics

Respecting individual demographic characteristics, the results of this study show that adult men are less likely than women to consume foods prepared at home by themselves, underscoring their traditional lower involvement in domestic cooking and suggesting a possibly higher reliance on others for food preparation and supply.^{(Reference Cerrato and Cifre59)} Adult men are also found to consume less home-prepared food than women in the United Kingdom, albeit the difference here being small.^{(Reference Clifford Astbury, Penney and Adams24)} Similarly, adult men have lower odds to eat meals prepared at home than women in the Republic of Korea.^{(Reference Lee, Song and Cho29,Reference Choi, Kim and Yoon30)} Meanwhile, in the present study, adolescents are more likely than children to consume foods prepared at home by themselves, relatives, or friends. Being more autonomous and independent than younger children, adolescents may more often leave school and return home at noon to eat a cooked lunch, rather than doing so in school premises.^{(Reference Cordovil, Lopes and Neto60,Reference Marzi and Reimers61)} This might explain why they eat relatively more food prepared at home. In the Republic of Ireland, where a cooked lunch is generally not provided at primary schools, older children (9–12 years) are found to be more likely to eat food prepared away from home than younger children (5–8 years), particularly products acquired from food retail and takeaway outlets.^{(Reference Burke, McCarthy and O’Neill36)} Furthermore, older adults in the present study are less likely to consume foods prepared at home by relatives or friends or prepared at restaurants, canteens, and other away-from-home establishments, than other adults, indicating a likely higher involvement in grocery shopping and domestic food preparation activities. Lower time and effort demands from work-related activities and the loss of income that accompany ageing and retirement probably explain why older adults resort more often to food prepared at home.^{(Reference Crompton and Lyonette62)} For instance, younger adults tend to consume more commercially prepared meals than older adults in the Republic of Korea.^{(Reference Choi, Kim and Yoon30)} Nevertheless, the consumption of home-prepared food by older adults in the United Kingdom is found to be similar to that of younger adults.^{(Reference Clifford Astbury, Penney and Adams24)} Lastly, although married/cohabiting adults are found to have higher odds of eating meals prepared at home than unmarried ones in the Republic of Korea,^{(Reference Lee, Song and Cho29,Reference Choi, Kim and Yoon30)} no associations between marital status and patterns of food preparation are observed in the present study.

Regarding household demographics, findings show that adults and older adults living in predominantly rural areas, as well as children and adolescents living in medium urban areas, are less likely to consume foods prepared away from home (by foodservice and food retail, respectively) than those living in predominantly urban areas. In line with this, European adults with the highest access to restaurants and medium access to grocery stores, both typical of predominantly urban areas, are shown to have the lowest likelihood of preparing meals at home daily.^{(Reference Pinho, Mackenbach and Charreire63)} Moreover, the adults and older adults in the present study who live in households with children or adolescents are more likely to consume food prepared by restaurants, canteens, and other away-from-home establishments than the remainder. Similarly, results from the US Department of Agriculture’s 2012/13 National Household Food Acquisition and Purchase Survey show that the presence of children (<18 years) in households increases their expenditures in fast-food and full-service restaurants.^{(Reference Saksena, Okrent and Anekwe64)} The food provisioning strategies of contemporary families may be a relevant explanation for the higher consumption of meals from out-of-home sources by households with children or adolescents. In particular, the purchase of convenience foods and ready-to-eat meals may be favoured as the consumption of such products typically lowers preparation, cooking, and kitchen clean-up times.^{(Reference Carrigan, Szmigin and Leek65)}

With respect to socio-economic variables, the adults and older adults with higher education or from households with higher income in this study are more likely to consume food prepared away from home than the remainder, whereas the opposite is true for those living in food-insecure households. High-income adults in the United States,^{(Reference Smith, Ng and Popkin6)} as well as adults who are employed, more educated, and of a higher economic status in the Republic of Korea,^{(Reference Lee, Song and Cho29,Reference Choi, Kim and Yoon30)} equally tend to consume less food from home sources. Conversely, university-graduated adults in the United Kingdom tend to eat slightly more home-prepared food.^{(Reference Clifford Astbury, Penney and Adams24)} All evidence considered, the balance between at-home and away-from-home food consumption is likely to constitute a fairly good indicator of the type and rate of socio-economic development of regions and countries; the distribution of income, labour, time, and expense within and between households; and the prevalence of gender and social inequalities in societies.^{(Reference Virudachalam, Long and Harhay26,Reference Adams, Goffe and Adamson66)}

Health and nutritional status, physical activity, and diet quality

Concerning nutritional and health status, the results of this study indicate that adults and older adults with higher consumption of food prepared by restaurants and other foodservice establishments are less likely to be overweight or obese than those more reliant on the food they prepare at home themselves. There are further no associations between food preparation patterns and weight or health status after adjustment for total energy intake, sex, age group, area of residence, and education. Extant systematic reviews and meta-analyses generally conclude for the existence of a positive link between the consumption of food away-from-home consumption and markers of NCDs, particularly BMI.^{(Reference Nago, Lachat and Dossa15,Reference Bezerra, Curioni and Sichieri57,Reference Godbharle, Jeyakumar and Giri67)} However, they also highlight that high variation as well as important limitations in how associations between eating out, diet quality, and nutritional status are typically studied weaken such conclusion,^{(Reference Mancino, Todd and Lin68)} with several cross-sectional and prospective cohort studies finding no or negative associations.^{(Reference Bezerra, Curioni and Sichieri57,Reference Wellard-Cole, Davies and Allman-Farinelli58,Reference Godbharle, Jeyakumar and Giri67)} On the other hand, cohort studies conducted in the United States and the United Kingdom suggest there is a preventive effect of increasing the frequency of consumption of homecooked meals, at the expense of eating out, on the risk of overweight, obesity, and type 2 diabetes, likely to be mediated by an improvement of diet quality.^{(Reference Mills, Brown and Wrieden34,Reference Taillie and Poti69,Reference Zong, Eisenberg and Hu70)} Findings from the present study, as well as from a French prospective cohort,^{(Reference Méjean, Lampuré and Si Hassen31)} do not support these hypotheses, however. Furthermore, several studies point out that the protective effects of increasing engagement in meal preparation activities at home on diet and health may be higher for household members than caregivers themselves.^{(Reference De Ridder, Lebacq and Ost71–Reference Chu, Addo and Perry74)} Meanwhile, aspects related to disposable income and lifecycle, such as household income class, size and composition, and engagement in the workforce are likely important moderators of the effects of food preparation and consumption practices on diet quality and BMI.^{(Reference Choi, Kim and Yoon75–Reference Crespo-Bellido, Grutzmacher and Takata77)} Beyond the regression analyses conducted in the present study, future studies should address the roles played by the aforementioned mediating and moderating factors.

With respect to lifestyle factors, the present study shows that, irrespectively of age group, individuals with a high intake of food they do not prepare themselves (i.e. meals prepared at home by relatives or friends or away-from-home by restaurants, canteens, and other foodservice establishments) are less likely to adhere to the Mediterranean diet and more likely to report low physical activity. Somewhat in line with this, adherence to DASH (Dietary Approaches to Stopping Hypertension) in the United Kingdom is linked to higher consumption of homecooked food among adults.^{(Reference Clifford Astbury, Penney and Adams24)} Noticeably, a previous pan-European study has also found evidence of a positive association between eating out of home and sedentarism.^{(Reference Orfanos, Naska and Trichopoulos42)} An important gap in research relating food preparation and consumption practices with physical activity remains, nonetheless, as most studies so far look exclusively at associations with diet quality and nutritional status.^{(Reference Mills, White and Brown17)}

Strengths and limitations

To the best of the authors’ knowledge, this is the latest of the very few studies to date that draw on a cross-sectional analysis of nationally representative food intake data, from both adults and non-adults, to investigate the demographic and socio-economic determinants of food preparation practices, as well as the putative associations of such practices with nutritional status, the prevalence of NCDs, and lifestyle choices.

Further longitudinal research is necessary to determine the direction of any causation between patterns of food preparation and correlates uncovered. Improving diet quality and increasing physical activity are essentially volitional, short-term behaviours, while the effects of such lifestyle changes on weight and, subsequently, health status are much less under the control of individuals and span across the course of years or even decades. This might help explain why, in the present study, a higher consumption of food prepared out of home, or at home by caregivers, correlates to poor diet quality and sedentarism, but not necessarily to a heightened risk of overweight/obesity or chronic NCDs. Historic individual data on nutritional status, any prior attempts to modify it (e.g. by dieting, increasing exercise and other means), and related outcomes are also likely to impact present-day food preparation and consumption choices and should thus be duly accounted for in future studies.^{(Reference Mancino, Todd and Lin68)}

The use of data from the IAN–AF 2015/16, which are now 8–9 years old, may not necessarily reflect the current situation in Portugal, especially after the onset of the COVID-19 pandemic. The pandemic may have significantly altered the dietary habits of the Portuguese population, potentially increasing at-home consumption due to lockdown and social distancing measures. Nevertheless, these are the most recent and comprehensive data from Portugal we are aware of on this topic. The MAI has not been validated in Portugal; however, this index has been indicated as good as the most utilised indexes or scores in Europe.^{(Reference Alberti, Fruttini and Fidanza44)} Even though residual confounding remains possible, logistic regression models were adjusted for a number of relevant potential confounders. Moreover, this survey followed a harmonised methodology of dietary assessment proposed by the EFSA,⁽⁷⁸⁾ allowing the collection of extremely detailed food consumption-related variables — which, consequently, enabled us to explore the food and beverage preparation places, regardless of the absence of a descriptor variable that exclusively had evaluated it. The food and beverage preparation place classification applied in this study has the advantage of internal consistency, because consistently defines what is prepared at home or away from home for all participants, based on data collected about food consumption — which may be less subject to desirability bias than the data collected about cooking behaviour (such as one’s ability to complete specific a priori food preparations or cooking frequency), mostly used in other studies.^{(Reference Virudachalam, Long and Harhay26–Reference Wolfson, Leung and Richardson28,Reference Adams, Goffe and Adamson66,Reference Raber and Wolfson79)} In addition, our system classification was informed by previously literature,^{(Reference Costa, Dekker and Beumer20,Reference Clifford Astbury, Penney and Adams24)} and this approach, in contrast to considering only the place of consumption reported for each eating occasion, holds the potential to acknowledge the intake of foods and beverages at home that were not homemade.