Get All Your Nutrition From Food | How Many Calories?

How To Get All Your Nutrition From Food

How Many Calories Do I Need In a Day?

In order to avoid the need to take a daily multivitamin it is possible to get all your nutrition from food.

First things first- I need to figure out how many calories to shoot for. I quick jump over to choosemyplate.gov reveals that the USDA recommends a male around my age acquire 2200 calories a day. Looking closer, I see that the estimated calories are for those who are "not physically active." While I wouldn't call myself a "gym rat" by any means, I would say that my activity level is more accurately characterized as "lightly active." So right off the bat, I know there will need to be some adjustments made here.

I also happen to notice that there is another column indicating the "Daily limit for empty calories." According to the USDA, it would apparently be fine for me to derive up to 12% of my 2200 calories from "food" that supplies no nutritional value. We'll see about that later.

In the meantime, I need to make my caloric adjustments. Luckily for me, I already have a spreadsheet handy that will do the calculations for me. There are, of course, a number of ways to make this calculation, depending on what kind of information is immediately available.

One equation known as the "Mifflin-Jeor" equation will calculate my basal metabolic rate (BMR) using my age, sex, height, and weight. A second equation known as the "Katch-McArdle" will calculate my BMR if my body fat percentage is also known. In turn, body fat percentage can be measured using a number of methods, or estimated using other equations and biometrics. According to my calculations, my body fat percentage is approximately 15%, and the Katch-McArdle equation declares that my body consumes about 1650 calories of energy just loafing around. For curiosity's sake, I checked to see what Mifflin-Jeor had to say, and that equation came in at 1700 calories per day. So the two are pretty close.

Now remember, this is my basal metabolic rate, which is the amount of calories my body consumes at a sedentary activity level. Since I am "lightly active" I need to make an adjustment to account for the extra calories expended during activity. My books tell me that I need to adjust that upwards by approximately 40%, for a grand total of 2300 calories a day. Those who are "moderately active" would adjust upwards by 50%, and those who are "heavily active" by 60%. Gym rats, marathon runners, and other extremely active people would need to add even more calories, but those calculations are beyond the scope of this article. At that point, you might want to seek professional help.

So, the first interesting thing I notice is the fairly sizable discrepancy between what the USDA is telling me, and what my equations are telling me. Remember, according to the USDA guidelines I would need to eat 2200 calories a day, if I were totally sedentary, while according to the scientific equations, I would only need 1700 calories a day. That means, if I were to follow the USDA guidelines, I would be happily packing on about one pound per week of body fat, and be totally confused as to why that might be happening.

Why the discrepancy? Who can really say. I would like to think that the folks over at the USDA are using the same equations as I am, but that does not appear to be the case. One confounding factor might be my weight. Since I weigh about 30 pounds less than the "average healthy male" I added another 30 pounds into my equations to see what turned up, but that only raised my predicted BMR from 1700 calories to 1900 calories, which leaves another 300 calories unexplained. Oh well, I guess we will leave that as a mystery for now, and move on.

Since we are clearly already in a gray area, I am just going to throw in a little fudge factor of 200 calories on either side, which brings my target daily caloric total to: 2100 – 2500 calories.

Total Daily Caloric Needs: 2100 - 2500 calories

Next Up: What Are My Macronutrient Ratios?