The number of calories consumed per day varies from person to person

That third usage corresponds to your basal metabolic rate,a number of calories you would need to survive if you weren't eating or moving around.Add in some physical activity and digestion,and you arrive at the official guidelines for how many calories the average person requires each day:2000 for women and 2500 for men.Those estimates are based on factors like average weight, physical activity and muscle mass.