How many calories you should eat depends on your age, size, activity level, and whether or not you need to lose or gain weight. 
The first step is to determine how many calories you currently burn over the course of a day, using the Daily Needs Calculator. Enter your age, sex, height, weight, and lifestyle (sedentary, some what active, etc.). You'll find some tips to help you select the appropriate activity level. There's also a place to enter in any additional exercise you might do.

Posted by:  Monica Reinagel, M. S. LD/N

'sedentary adj. 坐着的，坐着做的 a sedentary job