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Week 1 of My Fitness Pal Challenge- By Cindy Cervini

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How many calories should I be eating?

This is one of the most common questions that are asked by people when they first join a gym, especially if they desire to lose weight.  Usually it’s asked after several weeks, when someone has been working out differently than before, but does not change their eating habits and is becoming frustrated that the weight isn’t magically falling off, or they are not turning in to Iron Man and Rx-ing every WOD.  Many of us feel like by doing a little structured exercise we are given the green light to continue eating whatever we want.  But we’ve also all heard the saying “you can’t out train a bad diet”, and “it’s 80% diet, 20% exercise”.


One of the more accurate equations to determine caloric need is the Mifflin-St. Jeor Equation:

*Men:  RMR = (9.99 x kgs) + (6.25 x cms) – (4.92 x age) + 5

*Women:  RMR = (9.99 x kgs) + (6.25xcms) – (4.92 x age) – 161

*Kgs= lbs/2.2

*Cms=inches x 2.5

Multiply the RMR value by the appropriate activity correction factor:

1.200 = Sedentary (little to no exercise)

1.375 = lightly active (light exercise/sports 1-3 times per week)

1.550 = moderately active (moderate exercise/sports 3-5 times per week)

1.725 = very active (hard exercise/sports 6-7 times per week)

1.900 = extra active (very hard exercise /sports and a physical job)

For example:

A  40 year old, 70 kg man who is 5’8” (170cm), has a desk job and participates in CrossFit 3-5 days per week would calculate his daily caloric needs like this:

RMR = (9.99 x 70) + (6.25 x 170) –  (4.92 x 40) + 5

RMR = (699) + (1062) – (197) + 5

RMR = 1569

Now multiply the RMR value by his activity correction factor:

1569 x 1.550 = 2432 cals/day

Suppose this man wants to lose weight.  The gold standard to remember for weight loss is “eat less, move more”.   Create a calorie deficit.  That is, take in fewer calories than you expend during your day.  One pound consists of 3500 calories, so think about that….if you take in 250 fewer calories per day, as well as expend 250 additional calories, you will have a calorie deficit of 500 cals/day.  This adds up to 3500 calories per week, or a loss of 1 pound.  Of course, this is not an EXACT science, but it’s a great starting point.

In the case of our fellow, if he decreases his caloric intake approximately 250 cals per day  (takes in 2180cals/day), and burns about 250 cals per day in exercise (walking for 60 minutes), he would lose about 1 pound per week.

Now, let’s talk about what this man should eat.  Suppose he eats his 2180 calories in nothing but twinkies.  Would he lose as much weight as if he ate 2180 calories in chicken?   This is kind of like the old riddle—“what weights more, a pound of feathers or a pound of bricks?”  If you are maintaining a calorie deficit, no matter what you are eating you will still lose weight. Conversely, if you are eating greater than your daily caloric needs, whether it’s twinkies or free-range chicken and organic vegetables, you will gain weight.

Although the amount of calories is not really negotiable, the quality of calories certainly is.  A diet made up of protein, vegetables and fruits is certainly healthier than a diet made up of processed, simple carbohydrate foods.  Any simple carbohydrate (think white bread, cookies, candy, soda, pasta, etc) has no redeeming qualities, nutritionally speaking. Sugar is also associated with inflammation, which is connected to many health problems such as heart disease and cancer.

Eating higher quality foods will result in greater regulation of blood sugar as well as greater feelings of satiety (ie: less feelings of hunger).  Think of it this way—a car that is filled with regular gas (twinkies) will go the same number of miles on a full tank as when it is filled with super premium gas (chicken and vegetables), but the car will run better and more efficiently when filled with the super premium.

A great start to determine where you can make a change with your diet to improve your health is by honestly tracking your food intake.  Create a food log and document EVERYTHING you eat—every morsel!!—for at least a week to start. By doing this, you’ll be able to determine not only the amount of calories you are consuming, but also the quality of those calories as well.  Based on that, you will more easily see where you can make changes that will be beneficial to your health!