Calories: How Many Do I Need?

Determining your caloric budget–the number of calories you can consume–positions you to be more successful with your fitness goals; knowing your caloric needs empowers you with the knowledge to employ a more practical and sustainable strategy to achieving your fitness goals.  In this post we will introduce concepts including the Basal Metabolic Rate, Total Daily Energy Expenditure (TDEE) and Activity Level Multipliers that will be useful in determining a rough estimate of your caloric needs.  We will discuss macronutrients–proteins, fats and carbohydrates–in a later post.

The following are four (4) steps for calculating your caloric budget.

1. Establish Physical Fitness Goals
As you continue your health journey it is important to not just establish a desired measurable outcome, but also a realistic time frame to achieve this outcome; the goals you set will affect the number of calories you should consume.   It is also important to consider your current health status, if necessary, seek the advice of a doctor or nutritionist.  Fortunately, as you learn more about your body, you can adjust fitness goals accordingly.  Questions that you should be able to answer include:

• • What is my current health condition? Are there any restrictions that I must keep in mind?

• • How much fat or muscle do I want to lose/gain/maintain?

• • What is a reasonable time frame to achieve these results?

• Do I want improve my endurance/strength/power/flexibility?

2. Determine Basal Metabolic Rate (BMR)
Your Basal Metabolic Rate is an estimate of the amount of energy (calories) that your body expends when completely at rest.  That is, if you were to do absolutely nothing for 24 hours (not even eat), your BMR is the minimum number of calories needed to keep vital organs and systems–heart, lungs, skin, nervous system, etc–functioning.

Knowing your BMR is important because it is the first step in determining how many calories you need to maintain, reduce or increase your current weight.  There are several BMR calculators online however, we recommend this  BMR calculator on the MyFitnessPal website which is based on the following Mifflin – St Jeor Formula¹:

For men: BMR = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) + 5
For women: BMR = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) – 161

3. Estimate Exercise & Physical Activity
No fitness plan is complete without exercise such as weight lifting, walking, running, yoga, hiking, etc.  In this step, determine your daily/weekly exercise schedule and goals.  You should be able to answer these questions:

• What combination of exercises will I do?
• How many hours will I spend daily/weekly being physically active?

4. Calculate Total Daily Caloric Needs
Now that you’ve established your measurable goals, calculated your BMR and estimated your physical activity, you can now determine how many calories you need.  Using the appropriate activity levels multipliers you can get a very rough estimate of how many calories you need to consume each day.  The following activity levels are pulled from BodyBuilding.com:

• 1.30 = Very Light: Sitting, studying, talking, little walking or other activities throughout the day
• 1.55 = Light: Typing, teaching, lab/shop work, some walking throughout the day
• 1.65 = Moderate: Walking, jogging, gardening type job with activities such as cycling, tennis, dancing, skiing or weight training 1-2 hours per day
• 1.80 = Heavy: Heavy manual labor such as digging, tree felling, climbing, with activities such as football, soccer or body building 2-4 hours per day
• 2.00 = Very Heavy: A combination of moderate and heavy activity 8 or more hours per day, plus 2-4 hours of intense training per day

Your Total Daily Energy Expenditure (TDEE) = BMR x Activity Level Multiplier

Maintaining your current body weight, will require roughly the TDEE you calculated above.  To gain weight, you should exceed your TDEE and to lose weight you should create a caloric deficit by consuming less than your TDEE.  You can create a caloric deficit by increasing your physical activity or consuming less than you TDEE.   Please keep in mind that too large of a caloric deficit can lead to health issues or even compromise your weight-loss.  Consider starting with a caloric deficit that is around 20% of your TDEE; here’s another article on how to set a caloric deficit.

Now that you have determined your TDEE, you can determine how these calories can be allocated to your total protein, carb and fat intake.  In our post Macronutrients: Calculating Your Proteins, Fats & Carbs we address how you can estimate your macronutrients. If you’re specifically wondering about carbs, read “What You Need to Know About Carbs“.

REFERENCES

1. Macronutrients: the Importance of Carbohydrate, Protein, and Fat (2014, February 4) Retrieved January 3, 2016 from http://www.mckinley.illinois.edu/handouts/macronutrients.htm

2. M D Mifflin, S T St Jeor, L A Hill, B J Scott, S A Daugherty, and Y O Koh . A new predictive equation for resting energy expenditure in healthy individuals. J Am Diet Assoc 2005:51:241-247. http://ajcn.nutrition.org/content/51/2/241.abstract

3. A new predictive equation for resting energy expenditure in healthy individuals. Retrieved January 3, 2016 from http://ajcn.nutrition.org/content/51/2/241.abstract

4. Determining Daily Calorie Needs (2013, October 15). Retrieved January 3, 2016 from http://www.freedieting.com/calorie_needs.html

5. How to choose the proper activity level for the calorie-intake calculators? (2013, August 8). Retrieved January 3, 2016 from http://antranik.org/proper-activity-level-for-calorie-intake/

6. TDEE (BMR) Calculator Explained (2013, March 26). Retrieved January 3, 2016 from http://www.eattoperform.com/2013/03/26/tdee-calculator-explained/

7. Nutrient Ratios & Caloric Needs! (2015, April 3). Retrieved January 3, 2016 from http://www.bodybuilding.com/fun/issa64.htm