How many calories should one eat per day?

Mayo Clinic explains the number of calories an individual needs to eat per day varies based on body size and composition, gender, age and physical activity levels. Each person needs to first discover his basal metabolic rate to configure his optimal daily caloric needs.

The basal metabolic rate is the number of calories the body needs in order to perform basic human functions, such as breathing, circulation, organ function and cell maintenance, states Mayo Clinic. A person needs to eat the indicated number of calories in addition to the calories indicated for their specific physical activity level to reach his daily caloric needs.