Sedentary women require the fewest calories per day, especially overweight or obese sedentary women. According to the U.S. Department of Agriculture, sedentary adult women ages 19 to 25 require about 2,000 calories per day, sedentary women ages 26 to 50 require about 1,800 calories per day and sedentary women ages 51 and older require about 1,600 calories per day to maintain their body weight. According to Medline Plus, if you're sedentary or very obese you'll require about 10 calories per pound of your desirable body weight per day for weight maintenance, and if you're over age 55 or have a low activity level you'll require about 13 calories per pound of your desirable body weight on a daily basis.