Background: The coronavirus disease (COVID-19) pandemic has promoted changes in lifestyle behaviors, such as food consumption, sleep, and physical activity (PA). Few longitudinal studies have investigated these changes in young adults. Aim: This study aimed to assess lifestyle behaviors before and during the COVID-19 pandemic in young adult males. Methods: 50 young adult males (18–35 years) recruited by posters and social media in Florianopolis, Brazil, provided data on food consumption, PA, and sleep in 2018–2019 (baseline) and during the pandemic in 2020 (follow-up). PA and sleep variables were assessed through self-reported questionnaires. Food records were used to evaluate food consumption. Weight was measured using Bioelectrical impedance analysis at baseline and using self-reported at follow-up. Multilevel linear regression models and generalized linear multilevel were used to test differences between baseline and follow-up. Results: The findings indicated significant changes at follow-up, compared to baseline. Decreased consumption of total fat (β = −13.32, 95% CI (−22.45; −4.18), p < 0.01), sodium (β = −1330.72, 95% CI (−1790.63; −870.82), p < 0.01), cholesterol (β = −212.99, 95% CI (−269.8; −156.18), p < 0.01), total sugars (β = −65.12, 95% CI (−80.94; −49.29), p < 0.01), alcohol, and sugar-sweetened beverage were observed. Despite that, a slight increase in weight was also observed (80.70 ± 16.37 kg vs. 82.99 ± 15.42 kg, p = 0.000748). Sleep duration increased (β = 0.7596, 95% CI (0.41; 1.11), p < 0.01), and occupational PA decreased (β = −1168.1, 95% CI (−1422.33; −913.83), p < 0.01), while domestic (β = 394.04, 95%CI (114.68; 673.39, p < 0.01)) and leisure PA (β = 499.91, 95% CI (245.28; 754.53), p < 0.01) increased. Conclusion: Our results suggest that social distancing policies positively impacted eating habits, sleep, and PA patterns. These changes are possibly linked to increased awareness of the need for a healthy lifestyle.
