Evaluation of research as basis for recommendations about lifestyle is discussed and especially recommendations about nutrition. Nordic recommendations on nutrients and diet with emphasis on sustainability are published 2023. Randomized trials, the strongest background for evidence based knowledge, are sometimes not possible to use when studying the influence of lifestyle on health. A tool applied in the Nordic recommendations 2023 evaluates the strength of relation between exposures (nutrients and food groups) and outcomes (health and environment), where research methods are observed and an organized quality control applied. The Interngovernmental Panel on Climate Change (IPCC) estimates the share of food systems in global anthropogenic GHG emissions is 31% (23%-42%). Nations now work on cutting GHG emissions from food systems by strengthening food based dietary guidelines and including sustainability, which benefits both health and environment. The recommendations about nutrients 2023 use harmonized methods and new data on body size in the Nordics. The food based dietary guidelines 2023 meet people‘s requirements for nutrients and are healthy for the environment. Physicians and other health professions will have the possibility to stimulate people´s interest to adhere to the recommendations about nutrition and diet built on a stronger and broader basis than before.