Background: Due to the spread of COVID-19 infections around the world, in early 2020, the World Health Organization (WHO) announced a global pandemic, i.e. an epidemic of particularly large dimensions affecting countries and entire continents. Long-term stay at home and self-isolation may have significantly impacted lifestyle, diet, food choices and access to food, as well as physical activity in the entire population, including students. Objective: The aim of the study was to examine the impact of social isolation caused by the coronavirus pandemic on changes in diet, lifestyle and body mass index in a group of students, so that we would be better prepared for future new viral infections with characteristics similar to Covid-19. Material and Methods: he study was conducted in 2021 using a cross-sectional online survey (using the CAWI technique). The survey was addressed to students of universities in Poland who were over 18 years of age. After excluding forms completed incorrectly or with incorrect data, the final analysis of the results included the responses of 196 respondents. Statistical analyzes were performed in STATISTICA 13.3. Statistical significance was assumed at the level of p ≤ 0.05. Results: The study involved 136 women and 60 men with an average age of 23. The majority of respondents were residents of cities with over 500,000 inhabitants (50%), were students of 1st degree (45%) in medical/natural sciences (36%). The largest percentage of respondents (above 70%), before the pandemic and during isolation, had normal body weight, according to the BMI. There were significant statistical differences between gender and changes during COVID-19 pandemic in sleeping (p=0.013), physical activity (p=0.028), as well as the consumption of tea (p=0.047), milk and dairy products (p=0.041), alcohol (p=0.001) and red meat (p=0.003), vegetables (p=0.049), sweets (p=0.029) and fast food (p=0.004). Conclusions: Due to the fact that the impact of the coronavirus pandemic on the diet and lifestyle has been demonstrated, it is very important that the recommendations of public health organizations spread the message about rational nutrition and physical activity in the event of new viral infections among young people, including students.