MyNetDiary uses the official guidelines of United States Department of Agriculture (USDA) - Dietary Reference Intakes (DRI) provided on Food And Nutrition Information Center web site.
Based on information you provided - age, sex, weight, height, and activity level, MyNetDiary estimates energy and nutrient needs per these guidelines.
These estimates are shown on the "My Diet and Exercise Plan" page, in the first row of "My Daily Nutrition Plan" table. The estimates could be considered as a "baseline" helping you define your very own nutrition plan.
Please be aware that a significant deviation from the DRI recommendations could be dangerous to your health. We advise consulting a qualified dietitian.