This study utilized qualitative research to understand the changes taking place in adolescent dietary behaviors during the COVID-19 pandemic and the current status of school-provided nutrition counseling. These, along with barriers and strategies for improvement, were derived from focus group interviews with 10 nutrition teachers. Throughout the pandemic, adolescents experienced various dietary problems, including frequent meal skipping, unbalanced diets, increased obesity, and difficulties building positive attitudes towards food. To resolve these dietary problems, nutrition teachers recognized the need for school-provided nutrition counseling. However, nutrition teachers faced various barriers, such as a lack of time for nutrition counseling among students, lack of support from parents, and insufficient space and resources. To revitalize school-provided nutrition counseling, strategies such as home-connected nutrition counseling, the development of standardized guidelines, manuals for school-provided nutrition counseling, software support for nutrition diagnosis, and implementation of nutrition counseling in connection with cooking activities were proposed. This is important as school-provided nutrition counseling can help develop the foundation for healthy dietary behaviors and health promotion in adolescents.