Background

The rapid development of the new “Internet Plus” economic form and the increase in broadband penetration has promoted the continuous expansion of electronic transactions across the world [1,2,3]. Online services are gaining popularity due to the convenience of electronic transactions, the wide range of suppliers, and the expansion of delivery services [4, 5]. As a new form of food consumption that is rapidly develo** worldwide, online food delivery (OFD) provides consumers with online food ordering and delivery services, thereby changing traditional food production and retail practices. While solving the problem of time cost for individuals and families in food acquisition and preparation, OFD has also gradually changed consumer dietary consumption patterns. In particular, OFD has become more popular in the midst of the COVID-19 pandemic [6,7,8,9]. For example, although the size of the restaurant industry in China did not change significantly from 2019 to 2021, the size of OFD increased by 61.62% in the same time frame. In addition, the penetration rate of OFD increased from 3.87% in 2015 to 19.92% in 2021 [10]. In 2021, there were 544 million OFD users in China [3], and more than 40% of restaurants in China provide both online and in-person food services [11].

The global OFD market will reach USD 339.3 billion by 2022, and it is further estimated that the global OFD market will see its average annual growth rate remain at 8.28% from 2022 to 2026 [12]. The rise of OFD has greatly changed the food environment,Footnote 1 triggering changes in the practices of food production, transportation, and consumption worldwide. Consumers are increasingly buying food through online platforms, which has partially replaced traditional home cooking or dine-in patterns.Footnote 2

However, OFD may have negative effects. For example, by saving time spent on food shop** and home cooking, OFD may also reduce physical activity time, resulting in an increase in health problems associated with sedentary lifestyle [8, 13, 14]. Moreover, due to lack of information or labeling, it is difficult to guarantee the nutritional quality of OFD food [15,16,17], not to mention meeting the individualized nutritional needs [18, 19]. These may lead to a negative impact on public health. The increasing prevalence of chronic diseases in younger age groups due to dietary and nutritional health problems has become a widespread social problem in countries including China [20,21,22,32], resulting in the increasing and serious public health problems [4]. Zang et al. (2018) [33] found that the low nutritional quality of FAFH was manifested in increased intake of energy, fat, and carbohydrates by consumers. Goffe (2020) [15] pointed out that the convenient meals available via OFD ordering platforms popular with the global public were generally characterized by high energy and low nutritional quality. Based on data from three countries, Poelman et al. (2020) [16] suggested that the majority of foods through OFD were unhealthy, and that consumers living in communities with lower socioeconomic levels only had access to a smaller proportion of healthy food types. Partridge et al. (2020) [5] used data from two international cities to evaluate the characteristics and nutritional quality of foods on OFD platforms, concluding that the most popular foods on the platforms were unhealthy. Brar and Minaker (2021) [18] also reported that foods available on OFD platforms in Canada were of low nutritional quality and did not meet the requirements of healthy dietary guidelines. After assessing the nutritional quality and marketing attributes of food on Australian OFD platforms, Wang et al. (2021) [17] speculated that OFD platforms promote unhealthy food, and strongly suggested scholars to further conduct specific research on the nutrition of OFD foods. Similarly, Keeble et al. (2020) [34] emphasized the necessity to investigate how OFD affects dietary patterns and public health in their research.

Moreover, some studies have investigated specific health problems caused by changes in the food environment as a result of OFD. For example, FAFH, which is closely supported by OFD, has been shown to be generally high in calories, added sugar, saturated fat, salt, and low in nutritional value [26, 35,36,37,38]. These food characteristics have been proven as key risk factors for chronic diseases such as obesity, high cholesterol, diabetes, and hypertension [20,21,22,46], the evaluation in this study is based on the Dietary Guidelines for Chinese Residents (2022) (referred to as the Guidelines hereafter). The Guidelines were developed by the Chinese Nutrition Society after drawing on the dietary guidelines in other countries and translating the existing evidence on dietary nutrition into food-based dietary guidelines based on the reality of China. The goal is to help individuals maintain health and reduce the incidence of nutrition-related diseases. They are more in line with the characteristics and changing trends of Chinese citizens’ dietary structure and the reality of food production and supply in China. Using the Chinese Guidelines can avoid the bias caused by using the nutritional quality standards of other countries.

According to the Guidelines, the 12 food items that Chinese people need on a daily basis and their daily recommended intake are shown in Table 2. Following the scoring methods used by Reedy et al. (2018) [47] and Bar and Minaker (2021) [18] for the US Healthy Eating Index-2015 (HEI-2015), a maximum total score of 100 was established for a perfect balance of the 12 food items and their recommended daily intake (Table 2). Food combinations were scored accordingly. A higher total score indicates a healthier food combination. Healthier food combinations mean better balanced meals containing items from various categories. The higher the content of a desirable food item in the set meal, the higher the component score. However, the opposite is true for some other items such as sodium and cooking oil; in other words, the lower the content of these items, the higher the overall score.

Table 2 Dietary nutrition evaluation criteria
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The maximum scores for the 12 food items listed in Table 2 are not all the same. For example, the maximum score for poultry and meat (as a combined category) as well as aquatic products is 5, respectively, which are different from the maximum possible score of 10 for most other food items. There are two reasons for this. First, the Guidelines state that poultry, meat, and aquatic products are all animal products, and hence their nutritional components are complementary. Second, the maximum scores for total meats and seafood (as a combined category) and aquatic products set by HEI-2015 are also 5 for each category.

In addition, to evaluate nutritional quality, the following principles were used:

  • If a food item is present in the menu without content description, based on the principle of conservative estimation, it is assumed that the criterion is met and a corresponding score is assigned (for example, if “a serving of vegetables” was stated in the menu, a score of 10 would be assigned to “vegetables”);

  • If there is no set meal in the menu, the top three best-selling food items in the menu is selected and combined for nutritional quality evaluation;

  • If the text description in the menu does not match the picture, the text description prevails;

  • The contents of sodium and edible oil in the food are determined using Boohee.Footnote 6 Specifically, the content of edible oil can be estimated by calculating the sum of saturated, trans, monounsaturated, and polyunsaturated fats. If the content of sodium or edible oil cannot be determined in the software, the median score for that item, i.e., 5, is assigned.

Online survey

Questionnaire design

On the basis of previous qualitative research [9, 28, 46, 48], an online questionnaire was designed to evaluate current OFD consumption status, consumers’ perception of OFD food nutritional quality, and how OFD affects consumers’ health. The questionnaire contains two parts. The first part covers respondent demographics, such as gender, age, education, marital status, personal and family income, occupation, and the amount of OFD expenditure. The second part focuses on how respondents make OFD food choices, their nutritional and dietary needs, their perception of the nutritional quality of OFD food, and their perception of health after OFD food consumption. The detailed questionnaire contents are presented in the online supplementary material (see Additional file 1).

A small pilot test was first conducted to check the quality, accuracy, and readability of the questionnaire. The formal large-scale survey was conducted by creating an online link on a website and sharing the link via a professional marketing firm, which includes venues such as social media. Respondents’ informed consent was obtained on the first page of the questionnaire before commencement of data collection.

Sample demographics

The respondents of this paper must be the consumers with the experience of buying and consuming OFD food. According to this, and the questionnaires submitted by the respondents without such requirements are rejected. Table 3 shows the sample demographics of the survey. A total of 20,430 valid online questionnaires were collected from undergraduates, graduate students, and other young consumers aged 18–30. The majority of the respondents (87.37%) lived in cities of various sizes, which is consistent with the fact that OFD is more popular in urban than in rural areas in China [28, 43, 49]. Students, company employees, and public institution employees accounted for 34.51%, 30.25%, and 12.92% of the sample, respectively. Moreover, more than 80% of the respondents had a bachelor’s degree or above. In addition, 81.75% of the respondents had a personal pre-tax annual income of less than 150,000 yuan.

Table 3 Demographics of respondents
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Results

Results of nutritional quality evaluation of OFD foods

The 345 OFD set meals comprised 143 rice set meals (41.45%), 51 porridge and pastry set meals (14.78%), 49 crayfish and barbecue set meals (14.20%), 38 fast hot pots set meals (11.01%), 25 rice noodles and wheaten food set meals (7.25%), 13 fried chicken and skewers set meals (3.77%), 13 salad set meals (3.77%), and 13 pizzas and hamburgers set meals (3.77%).

The nutritional quality evaluation of three example OFD set meals is given in Table 4. Out of a maximum score of 100, the total score of the three OFD set meals ranged widely from 15 (crispy fried chicken set meal) to 85 (beef and chicken breast salad set meal), with a mean of 36.57 out of 100. In particular, as Fig. 1 displays, of all the set meals considered in this study, 65.05% scored below 40, and 89.56% scored below 50. It is thus clear that most OFD set meals have poor nutritional quality falling far below recommended values. They lacked fruit, milk and dairy products, aquatic products, whole grains and beans, soybeans and nuts, and eggs, and were high in sodium and cooking oils. The only food items with high scores were poultry and meat, and cereals.

Table 4 Nutritional quality of three example meals through OFD evaluated based on the Guidelines
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Fig. 1
figure 1

Distribution of nutritional quality scores of OFD foods (% in total sample)

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Figure 2 shows the nutritional quality scores of different meals ranked according to frequency of purchase. In particular, “salads”, which ranked seventh in terms of frequency of purchase, scored the highest in nutritional quality. “Rice meals” and “porridge and pastry” ranked first and second in terms of purchase frequency, together accounting for more than 50% of the total sampled meals. However, both had a nutritional quality score of less than 40. This suggests that the OFD foods consumed by more than half of the consumers did not meet the Guidelines’ dietary nutritional recommendations.

Fig. 2
figure 2

Nutritional quality scores of OFD meal types ranked by purchase frequency

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Online survey results

Consumer perception of nutritional quality

Based on the online survey results, the popularity of the 13 OFD meal types is illustrated in Fig. 3. Obviously, “rice meals” were the most popular, accounting for 57.56% of the sample. This is in line with the data collected from the OFD platform reported in this study. However, as Fig. 2 suggests, the mean nutritional quality score of this meal type was only 36.14, which was 33.30 points lower than the highest score, which was earned by “salads” (Fig. 2). Because “milk tea and desserts,” which ranked second in popularity, are generally not considered a daily meal type, data were not collected for this category from the OFD platform. Therefore, the nutritional quality of “milk tea and desserts” was not evaluated in this study. However, according to Li and Yang (2017) [50] and Zheng (2021) [51], milk tea is generally an unhealthy food. The nutritional quality scores of “pizzas and hamburgers,” “fried chicken and skewers,” and “crayfish and barbecue,” which respectively ranked third, fourth, and fifth, had nutritional scores of 32.78, 29.58, and 27.43, far from meeting the Guidelines’ dietary nutritional recommendations. In contrast, “salads,” the meal type with the highest mean nutritional quality score shown in Fig. 2, had a very low purchase frequency of 7.34%. It ranked 11th in the list of 13 options in Fig. 3, which is consistent with the data collected from the OFD platform.

Fig. 3
figure 3

Proportion of popular OFD meal types based on online survey data (%)

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As shown in Fig. 4, when making OFD food choices, 52.91% of the respondents paid most attention to taste, followed by price and delivery speed, and lastly nutritional value. This shows that consumers had low concern for dietary nutrition and health. In addition, respondents’ level of attention to dietary nutrition knowledge is shown in Fig. 5. Only 12.97% of respondents paid attention to this knowledge often and 33.43% occasionally paid attention. The majority either rarely or paid no attention at all. This result may indirectly indicate that the general public in China has not been too concerned about dietary nutrition. Young people in China have a low interest in acquiring, understanding, and using dietary nutrition knowledge related to their health. In addition, another possible reason for this result may be that young consumers tend to think they are overall healthy and thus care little about acquiring or using this knowledge.

Fig. 4
figure 4

Concerns when ordering food online (%)

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Fig. 5
figure 5

Level of attention to dietary nutrition knowledge (%)

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Consumer health perceptions

The online questionnaire also included consumer self-evaluated physical health changes after long-term consumption of food through OFD. As shown in Fig. 6, 57.46% of the respondents believed that long-term consumption of food through OFD led to their weight gain. Nearly 50% reported increased blood lipids and gastrointestinal discomfort. Only 17.47% believed that long-term consumption of food through OFD had no effect on their physical health. Therefore, this study supports the notion that popular food ordered through OFD does not meet consumers’ daily nutritional needs. Long-term consumption of food through OFD may have a negative health impact, and should be included in the public discussion on how food through OFD may be related to chronic diseases, such as obesity, hyperlipidemia, hypertension, and type 2 diabetes.

Fig. 6
figure 6

Perceived health changes after long-term consumption of OFD food (%)

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In addition, the respondents who believed that consuming food through OFD had an impact on their health were further asked about the signs and reasons of such a health impact (Fig. 7). The most reported reason was excessive cooking oil (79.00%), followed by high salt content (63.44%), high sugar content (50.32%), and improper balances of different types of food (30.64%). Obviously, the problem of high oil, salt, and sugar intake, which can lead to chronic diseases such as obesity, hyperlipidemia, and hypertension [52, 53], is of concern to consumers. It indicates that consumers are well-educated in this respect. However, the fact that of food ordered through OFD has improper nutrition balances has not been given adequate attention by young consumers.

Fig. 7
figure 7

Reasons consumers believe that food through OFD does not meet health standards (%)

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Robustness test

In order to ensure the robustness of the cross-sectional study method and the representativeness of samples, this paper also collected data of OFD food around other types of ordering places. Similarly, using the Dietary Guidelines for Chinese Residents (2022) as the standard to evaluate the nutritional quality of OFD food by cross-sectional research method. The most popular shop** malls in 20 citiesFootnote 7 in China were selected as the OFD ordering places. The data of set meals from the top three restaurants with monthly sales volume around each shop** mall were selected as samples, that is, the set meals with the largest sales volume in 60 restaurants were selected as samples to evaluate the nutritional quality. The results show that the average score of nutritional quality assessment of the 60 online meals was 37.65 out of 100, among which 63.85% of the meals scored less than 40 out of 100, 89.05% of the meals scored less than 50 out of 100. The types of meals were also relatively single. It is not difficult to find that still be concluded that the nutritional quality of OFD food is generally low after selecting different types of places for ordering OFD food.

Conclusions and policy implications

This study uses the best-selling set meals of the 345 most popular restaurants surrounding 115 universities in China as the basis to gauge the nutritional quality of food through OFD. The study uses data obtained from the super-leading OFD platform provider Meituan and creates the nutritional valuation based on China’s Dietary Guidelines for Chinese Residents (2022). A follow-up online survey was administered among undergraduates, graduate students, and other young groups aged 18–30. The survey investigated consumer choices of food through OFD, as well as their perception of the nutritional quality and health impact of food ordered through OFD. We find that foods acquired through OFD generally had low nutritional quality scores. This is consistent with the findings of Bar and Minaker (2021) [18] regarding the nutritional quality of foods though OFD in North America. Meal types popular with young consumers had low nutritional quality, far from meeting the recommendations of the Guidelines. Relatedly, meal types with high nutritional quality were not common choices for young consumers. Furthermore, the vast majority of young consumers only paid attention to the taste and price of food, but ignored the nutritional value when using OFD. They generally had low awareness and might even lack basic appreciation of dietary nutrition and health. Weight gain, increased blood lipids, and gastrointestinal discomfort were the most common physical health changes perceived by young consumers after long-term consumption of food through OFD.

Our results may provide insights into improving the nutritional quality of food through OFD. The implications can be on both the supply side and the demand side [54]. Like in most countries in the world, a restaurant or food service usually does not make all their food items available for online ordering. For food providers, reducing the amount of unhealthy food and increasing the amount of healthy food offered through the online platform might be an essential component to improve the nutritional quality of food through OFD. However, if such an action reduces profit, food providers may not be willing to commit. This will need the effort from the demand side. Consumer education campaign can promote consumer awareness and knowledge about their nutritional health and reduce the intake of unhealthy or imbalanced food. As far as China is concerned, based on the fact that dietary nutrition and health knowledge has not received widespread attention from young consumers, efforts should be dedicated to this particular group to promote the Dietary Guidelines for Chinese Residents (2022). Many individuals order food through OFD due to its convenience, thus, increasing the convenience of healthy food preparation for consumers might assist consumers making healthier choices. More drastic approaches that may encounter some level of pushbacks but can nevertheless be powerful include limiting the amount of unhealthy food by each customer per order.

Several areas of extension exit. First, an immediate venue is to apply our framework to the broader public to include consumers of all ages. Second, consumer heterogeneity such as age and gender may lead to large variation in their food ordering and nutritional health response to OFD. Further work to explore this heterogeneity and establish situational context of OFD is likely useful. Third, we used respondents’ self-reported health status to describe the impact of food through OFD. Additional investigation can consider tying food nutritional data with the amount and variety of ordered food through a consumer diary. Finally, one can apply the framework and test the general applicability of the conclusions in this study in a non-Chinese context.