How to Calculate Fat Grams Needed Per Day

Before you determine how many fat grams you need per day, you need to know how many calories you need to consume to maintain your weight. One of the most accurate ways to calculate this is with the Harris-Benedict formula. This will help you figure out a diet best suited for you.

Things You'll Need

• Calculator
• Scale
• Tape measure

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Instructions

• 1

  Measure your height and weight.

• 2

  Using the Harris-Benedict formula, calculate your basal metabolic rate (BMR). This will allow you to calculate an accurate number of calories needed per day because it factors in height, weight, age, sex and physical activity, as opposed to just body weight.

  For men, the BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in years)

  For women, the BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years) (resource 2)

• 3

  Multiply by the following according to your level of physical activity:
  • Sedentary (You get little or no exercise) = BMR x 1.2
  • Lightly active (You do light exercise 1 to 3 days per week) = BMR x 1.375
  • Moderately active (You moderately exercise 3 to 5 days per week) = BMR x 1.55
  • Very active (You do hard exercise 6 to 7 days per week) = BMR x 1.725
  • Extra active (You do hard exercise every day and have a physical job, or you train twice a day) = BMR x 1.9

  This equals an accurate estimate of your total daily energy expenditure (TDEE), which is how many calories you need to consume to maintain your weight.

• 4

  Decide on the percentage of calories you should get from fat. The Dietary Guidelines for Americans, 2005, suggests 20 to 35 percent of your daily calories should come from fat.

• 5

  Multiply your TDEE by the percentage of fat calories you want to aim for. For example, if your daily calorie intake is 2000 and you aim to eat 30 percent fat calories, multiply 2000 x .30 = 600 calories from fat.

• 6

  Because there are 9 calories in one fat gram, divide your calories from fat by 9. In the example, 600 / 9 = 66.67, or rounded up, 67 grams of fat. So, if you aim to eat 30 percent fat calories, you should consume at most 67 grams of fat per day.