How Many Calories Should Be Eaten in One Day?

According to the CDC, 2/3 of Americans are overweight or obese, meaning most of us are eating way too many calories. Calories are units of energy that measure the amount of heat required to raise the temperature of one gram of water one degree Celsius. The amount of calories you should eat each day depends on several factors. Calories recommendations differ for males and females, and activity level plays a big part.

Calculate BMR

• Use the Harris-Benedict equation to calculate the number of calories you need in one day based on your activity level. First, calculate your BMR, which stands for basal metabolic rate and means the number of calories your body needs at rest each day.

  For males, BMR = 66 + (6.3 x body weight in lbs.) + (12.9 x height in inches) - (6.8 x age in years)

  For females, BMR = 655 + (4.3 x weight in lbs.) + (4.7 x height in inches) - (4.7 x age in years)

Use the Activity Multiplier

• Use the activity multiplier after you have calculated your BMR to determine how many calories you should be eating in one day based on the amount of exercise you get. Sedentary means that you get little-to-no activity each day, light active means you get just a little bit of exercise on average each day, moderately active means you average some amount of light exercise each day, very active means you average some moderate-to-intense exercise most days of the week, and extremely active is for people who are getting intense exercise very frequently, such as endurance athletes.

  Sedentary = BMR X 1.2
  Lightly active = BMR X 1.375
  Moderately active = BMR X 1.55
  Very active = BMR X 1.725
  Extremely active = BMR X 1.9

Calculate Your Calorie Needs

• Here's an example of how many calories should be eaten in one day by a 5'5" 150 pound woman who is moderately active and 40 years old:

  BMR = 655 + (4.3 x weight in lbs.) + (4.7 x height in inches) - (4.7 x age in years)

  655 + (4.3 x 150) + (4.7 x 67) - (4.7 x 40) = 1427

  Activity multiplier = 1.55

  1427 x 1.55 = 2211 calories per day

Important Considerations

• It's important to note that research from the Nutrition Research journal suggests that formulas such as the Harris-Benedict equation that are used to calculate energy needs should take into account weight history and ethnicity.