text: What Is the Least Amount of Calories I Can Eat in a Day? | livestrong
  Chopping celery on a cutting board.
  Calories provide energy you need for daily activities. When trying to lose weight, the calories you take in should be less than the calories you burn, but there is a limit beyond which you should not go unless you're under medical supervision.
  Women should not consume less than 1,200 calories a day for safe weight loss, while for men, the lower limit is 1,500 calories per day, according to the Harvard Medical School publication,"HEALTHbeat." However, the National Institutes of Health notes that most women can safely lose weight consuming 1,000 to 1,200 calories a day, while men can consume 1,200 to 1,600 calories for safe weight loss. It's always best to consult with your doctor before you start any weight loss program to determine what is the appropriate amount of calories for you to consume daily, which will depend on your age, gender, activity level, current weight and dietary habits.
  For a rough estimate of calories needed to maintain your current weight, simply multiply your weight by 15 if you are moderately active and 12 if you are not. To lose weight safely at 1 to 2 pounds per week, create a calorie deficit of 500 to 1,000 calories a day through a combination of diet and exercise.
  Having a balance of the right amount of calories over time helps you maintain a healthy weight. If you eat too few calories one day, make up for it the next day. If you eat too many calories, reduce the amount you have the following day.