A Dietitian’s Most Feared Question….?

As a dietitian, one of the most common questions people ask is, “How many calories should I eat?” If you are a dietitian, be cautious of the following reactions which may occur following this question: deer-in-the-headlights eyes, frozen facial expression, inability to speak, feeling of lead-filled limbs, vacated vocal chords and frozen blood in your veins. It’s like showing a banana slug a jar of salt. That question is our kryptonite.


Because every person who asks that question expects a simple, cut and dry answer. Or number, I should say. But the simple answer is…it depends on many different factors. That is why dietitians freeze on command because it’s not a question we can simply answer. Hence, the following discussion on math. (Yes, we are headed back to high school).

So…I bravely pose the question…How Many Calories Should I Eat?

The answer depends on the following factors:

1. Gender

2. Height

3. Weight

4. Activity Level

5. Goals – do you want to lose weight? gain muscle? train for a marathon? gain weight?

6. Age

Once you’ve determined these factors, there are several methods to determine how many calories an individual should eat daily. There are online tools which do the calculations automatically, or you could take the time to manually calculate the formulas. Either way will give you a reliable range.

Whichever method you use will use a combination of an estimated Resting Metabolic Rate (RMR) or Basal Metabolic Rate (BMR) and Physical Activity Factor. The RMR or BMR calculations will estimate how many calories your body would burn in a sedentary state, i.e. if you stayed in bed all day. These are the calories simply needed to keep your body, brain and muscles functioning. Most of us don’t spend all day in bed, therefore we need to account for movement and exercise throughout the day. To account for these calories, these calculations will include a Physical Activity Factor ranging from sedentary to vigorous activity.

So let’s put it all together:

STEP 1: Determine your six individual factors (above)

STEP 2: Determine your RMR or BMR. This can be done by simply adding a zero to your weight. That will give you a rough estimate of how many calories your body would burn at a resting state. If you want to get technical, you can calculate your BMR by using the following formula, respectively:

Women: BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) – ( 4.7 x age in years )
Men: BMR = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) – ( 6.8 x age in year )

STEP 3: Select your activity factor and multiply your BMR by your activity factor. This formula is called the Harris Benedict Formula.

  1. If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
  2. If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
  3. If you are moderately active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
  4. If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
  5. If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9

STEP 4: What’s your goal? If you want to lose weight at the rate of one pound per week (which is recommended) then you’ll subtract 500 calories from your total you just calculated. If you want to gain weight at the rate of one pound per week, you’ll add 500 calories to each day. If you want to maintain, then leave the total number as it is.

*For all those who considered math their “area of improvement” click this link to calculate your total daily calories: http://www.caloriesperhour.com/index_burn.php and click “BMR/RMR Calculator.”

Ok, phew, we made it! My fingers are still typing and my blood pressure remained normal. As you can decipher from the formulas, the more you exercise then the more food you can eat throughout the day. But vis versa is also true.

Today’s Challenge: Calculate how many calories you should be taking in per day.

Use this number as a ballpark figure to keep in the back of your brain. You don’t need to start obsessing over calories, just start to be aware of what and how much you are eating in comparison of your total daily allotment. Think of it almost as a budget…whatever you take out comes from your daily allowance.

So ask yourself…What are you willing to spend your calories on this week?



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