Health status and the bmi is the major concern. For example, an active man of 70 kg requires about 2700 to 3000 calories per day depending upon the intensity of his physical activity. On an average, a healthy man needs about 2500 calories to maintain his weight. Men older than 50 years of age need 2000 to 2800 calories depending on how active they are. Though it differs depending on age and activity level, adult males generally require 2,000-3000 calories per day to maintain weight while adult females need around 1,600-2,400 according to the U.S Department of Health.