As the study is regarding seasonal variations, the major changes in the scope of the following months, from January to December, is discussed.
January is a period of both, New Year’s resolution and the carnival period. The first social phenomenon might enhance an individual’s motivation, while the second might attenuate it. A rapid increase in Google searches related to diet, dieticians, dietary supplements, weight loss, and gym, was observed at this time. Cherchye et al. observed that the consumption of healthy foods surges globally in January and gradually decreases over the year . Reports of the International Health, Racquet, and Sportsclub Association confirmed that the highest number of gym membership sales is observed in January . This phenomenon indicates that January might be a period of increased motivation for lifestyle changes. Importantly, previous reports state that the New Year’s resolution might a strong motivator, but the long-term effects of the decisions are poor [10, 27]. Therefore, an individual plans must include further follow-ups to maintain motivation of individuals. Index sales of most of the consumer goods decrease in January as compared to the previous month.
In February, students in Poland have two-weeks of winter holidays. This time may be associated with a decrease in sales due to travel abroad and family journeys. The forty days preceding Easter, known as Lent, begin at this time. Lent is traditionally related to personal resolutions and involves refraining from a pleasure or bad behavior [28, 29]. In Poland, almost 34 million, out of 38 million citizens, are Christian, mostly Roman Catholics . Therefore, it may assumed that both the winter holidays and the tradition of Lent’s resolution may affect consumption. It was observed that in February, the sale of all types of products decreases as compared to previous months and this is consistent with national sale trends of non-durable consumer goods . The decrease in sales was particularly notable for cigarette purchases. Furthermore, the interest in diet, dieticians, dietary supplements, weight loss, and gyms, remains high in comparison to the other months. Therefore, February in Poland, could be another month in which consumers have high motivation for lifestyle changes. In Croatia, there were massive public health campaigns encouraging smoke cessation during Lent with promising results [29, 32]. Such religiously-motivated interventions may be efficient, but further studies are needed to establish the same .
Base on the beginning date (Ash Wednesday), Lent lasts through March and even up to April, till Easter. In March and April, the increase in sales of sweets is most notable, and this may be associated with the tradition of gifting sweets to children for Easter . As compared to February, purchases of other products also increase other than that of processed fishes and food fats, which is the lowest during April. It was observed that Polish Google users were still highly interested in lifestyle-related topics, but the relative search volumes decreased in comparison to January and February. The beginning of the spring may be the period when the hype of the New Year’s and Lent resolutions decreases. Therefore, it is crucial to communicate to individuals, who made a decision to change their lifestyle at the beginning of New Year or Lent, that March and April might be a period when motivation drops.
The highest interest in running is seen in May. Therefore, this period might be promising for pro-running health campaigns. Importantly, the campaign must involve weather forecasting to assist people to choose the optimal period for outdoor activities. At this time, the interest in other lifestyle-related topics continues to decrease from previous peaks, while the sales indexes of products consumed mostly in summer months increases. Furthermore, in May the activity of Polish Internet users is also slightly lower than that in colder months which is observed in monthly surveys of Polish Internet Researches (pl. Polskie Badania Internetu) .
The warmest period in Poland is from June to September. The summer holidays for schools begin in the last week of June till the end of August, while university students have an additional month of holidays, and the academic year begins in October. The consumption of ready-made meals, salty snacks, meats, beer, and cigarettes is the highest during these months. This a period of barbecue parties, holiday trips, and festivals, thus the sales of meat (e.g., sausages), snacks, alcohol, and cigarettes, increases . Holiday activities may tempt individuals to follow an unhealthy diet pattern. Practitioners should encourage patients to maintain a healthy regime at this time. Skutecki et al. found that the triglycerides serum levels peak during summer months in Poland , and this may be because of the consumption of processed meat, snacks, and beer. Interestingly, the dairy sales index also peaks in warm months. The dairy consumption is most useful during cold months as there is limited insolation for Vitamin D. It is estimated that two-thirds of Poles suffer from Vitamin D deficiency . This study speculates that cold dairy from a fridge may be tastier for consumers in summer months as during this period the consumption of dairy products increases . However, it is crucial to promote dairy consumption during the cold season. Furthermore, the interest in healthy lifestyle-related topics is the lowest during the warm period. This drop may be associated with the lower time spent online during summer months as compare to the colder periods .
The second peak of interest in running is observed in summer. The weather is colder and people may be motivated to participate in outdoor activities after returning from holidays. This offers a potential period for the promotion of running.
The consumption of a number of goods decrease in autumn, but the purchase of sweets increases in comparison to summer. In Poland, sales of sweets are seen to peak before important holidays like Christmas and Easter , and during autumn . Notably, most Polish people admit that they consume sweets compulsively and to improve their mood [41, 42]. Therefore, the increase in prevalence of depressive symptoms during this time may drive more people to consume sweets to improve their mood [43, 44]. Moreover, there is an increase in interest in diet, dietitian, dietary, and gyms in autumn, as compared to the summer. The weight gain during holidays could be motivation for a healthy lifestyle after people return to work or school . Therefore, early autumn might be another optimal time for lifestyle interventions.
December is the month of Christmas and winter holidays. During this period, there is a peak in sales of processed fish and food fats. This may be related to the special Christmas time meals. The highest purchases of wine and strong alcohol could be associated with the New Year celebration . Inversely, the interest of Google users in analyzed topics decreases during Christmas. These changes may be related to the lower activity of Web users, which has been suggested in past surveys [35, 47]. Christmas holidays can be a tough period for people who want to consume a healthy diet. Napierała et al. calculated that during Christmas, the average energy intake is approximately 2400 kcal, and the final weight gain after the holidays is estimated to be 420 g . Moreover, an increase in total cholesterol levels has been observed after Christmas . Therefore, it is important to educate the Polish community about traditional meals that should be preferred for health reasons. It may also be crucial to motivate people to increase their efforts to maintain good health after the Christmas holiday period ends and New Year begins.
Among food products, the most dynamic was the increase in sales of ready-made meals and salty snacks. The surge of consumption of processed foods might be related to an increase in unhealthy diet pattern among Polish adults observed in the last years . The changes in sales of food products seem interesting, but they may be affected by the food supply, the introduction of new products, etc. Therefore, in our opinion, a new study should be performed to analyze secular trends in sales, and more chains should be compared.
The Polish Google users became more interested in searches related to dietitians and dietary supplements while less on physical activity and diet. Therefore, it may be related to unfavorable trends to search for an easier solution for losing weight or expansion of the dietary supplementary market and dietitians’ services. However, the problem requires further studies.
Strengths and practical implications
As per our understanding, this is the first study that comprehensively investigates the seasonality of various lifestyle factors together. Previous research primarily focused on exercise and weight loss related searches in GT . This study analyzes both, the sales indexes and the GT queries. It provides useful insights regarding consumption and the seasonal fluctuation in the interest in healthy habits. The findings may have practical implications. Furthermore, periods that might be optimal for lifestyle intervention for the entire population and at the individual level, have been identified. These findings may provide a background for future studies and for designing health promotion campaigns.
This study has several limitations. Firstly, the data does not present information about gender, age, and other characteristics of consumers and Google users. Secondly, commercial data has been collated from only one franchise, and the company did not disclose the number of purchases of consumer goods due to trade secret. Thirdly, the group of products is limited because not all facilities of the retail store chain include stands for fruits, vegetables, and organic (bio/eco) food. Fourthly, documentation about food supply and utilization has not been included. Limited food supply may affect sales indices. However, according to the store chain, “The food supply for the most popular products is practically not limited for franchisees, and we are rarely notified about problems with supplies. The more prevalent problem is a large amount of expired food which requires regular utilization” (personal communication, March 2021). Finally, the interest in different healthy behaviors among Google users does not mean that people tend to visit the gym, dietician, etc. more commonly. The search statistics might reflect general tendencies, but this is not the direct measurement of healthy behavior.