In Peru, one of the first interventions to flattened the epidemiologic curve of the pandemic was quarantine that changed eating behavior, physical activity and mental health of the population. Objective: to determine modifications in eating behavior, physical activity and mental health in young adults before and after the quarantine. Methods: cohort study involving 384 adults from 18 to 24 years of age that were subjected to a virtual interview and application of an international questionnaire to evaluate changings in eating behavior, physical activity and mental health contrasted by Chi square. Results: an increase in the distribution of daily foods [breakfast (p<0.001), morning snack (p<0.05), lunch (p<0.001), afternoon snack (p<0.001), dinner (p<0.05)] and an increase in ingestion of fruits (p=0.005) and reduction in the ingestion of fast food (p<0.05) and candies (p...