This is an important question.  Knowing the answer to both parts of the question will play a vital role in your success.  Let’s examine the first part of the question; how much do I eat?  The average person underestimates their food intake by 10-20%.  This means that if someone stated they are consuming 2000 kcals per day the actual number may be closer to 2200-2400 kcals.  Day to day this representation may be insignificant but it quickly adds up.  As an example you could gain 1lb every 8.75-17.5 days (approximately 3500 kcals equates to 1lb.  3500/200 extra kcals per day= 17.50 days and 3500/400 kcals extra per day= 8.75 days).  Over the course of 1 year that could equal 21-42 lbs. of additional weight.

Now let’s examine the second part of the question; how much should I eat? There are a variety of methods and devices to help to determine the amount of calories to consume.  Most devices are not readily available and can be quite expensive.  To estimate the amount of calories you need to consume let’s talk about Resting Metabolic Rate (RMR).  Stated very simply RMR is the amount of calories the body needs to function at rest.

How to calculate RMR (Mifflin-St. Joer Equation)

Women RMR= {(9.99 x BW in kg) + (6.25 x Ht in cm)} – (4.92 x age) – 61
Men RMR= {(9.99 x BW in kg) + (6.25 x Ht in cm)} – (4.92 x age) + 5

In order to use the equation you will need to know and or determine the following information:

  • Age
    ·         Gender
    ·         Weight (convert from pounds to kilograms  lbs/2.2kb)
    ·         Height (convert inches to centimeters inch/2.54cm)


  • 40 y.o.
    ·         Male
    ·         220 lbs or 100kg
    ·         77 inches or 195.58 cm

RMR = {(9.99 x 100 kg) + (6.25 x 195.58)} – (4.92 x 40) + 5 = 2034.495 kcals.

2035 kcals represents the number of calories needed on a daily basis to meet the body’s daily caloric expenditure at rest.  This number doesn’t include activity.  To include activity an activity factor is necessary.

Activity Factors

Category Physical Activity (PA) Activity Factor Est. Using our example; RMR = 2035
Sedentary <30 min of PA per day 1.2 2442 kcals
Light Activity Light Exercise or  PA 1-3 days/week 1.375 2798 kcals
Moderate Activity Moderate Exercise 3-5 days/week 1.55 3154 kcals
Very Active Hard Exercise 6-7 days/week 1.725 3510 kcals

The challenge is to select the right activity factor.  Most individuals that I encounter would describe themselves as light to moderately activity, but are in reality sedentary to lightly active.  The difference is approximately 356 kcals.

Using the RMR equation will provide a good approximation of the amount of calories you should be consuming.   The next article will discuss how to increase your RMR and how to create a caloric deficit to lose fat.  In the mean time think about Non-Exercise Activity Thermogenesis (N.E.A.T).  NEAT is defined as any activity done outside of exercise, such as taking the stairs vs elevator at work, picking a parking space further from the store to add extra steps or standing vs sitting during the day to name a few.   What other ways can you think of to increase your NEAT?