WARNING - do not read this column without a calculator in hand - calories are closer to you than they may appear in mirror.
Not everyone has the same, "based on a 2000 calorie diet" caloric needs. Here are some equations to play around with while you are, A) eating lunch by yourself and pretending to be engrossed in the paper, B) sitting in lecture and can't unscramble the word jumble, or C) waiting in the campus center for your extremely hot writing fellow.
It's important to know your body's daily caloric needs so that you can adopt a realistic diet and physical activity plan to help maintain a healthy weight. Maintaining a healthy weight protects you from numerous chronic diseases and provides many health benefits.
According to the Food and Drug Administration's (FDA) 2005 Dietary Guidelines, being overweight or obese increases your risk for high blood pressure, high blood cholesterol, heart disease, stroke, diabetes, certain types of cancer, arthritis, and breathing problems. A healthy weight is key to a long and healthy life.
The first step is to figure out your basic energy needs according to your age, gender, size and weight; this is called your "basal metabolic rate," or BMR. Your BMR is the amount of calories you burn just by being alive - even when you are lying down, doing nothing.
Then, between 20 to 50 percent of your daily caloric needs are determined by physical activity. You also burn a small amount of calories to digest and metabolize food. This is known as the thermic effect of food. Add the calories you will need to support your training activities (based on the type, duration, and intensity of exercise) to your BMR and energy needed for the thermic effect of food, and you've got your estimated total caloric intake for the day.
To estimate your daily caloric needs, you can use what's known as the Harris-Benedict equation. This equation is one of the most commonly used amongst nutritionists, but there are others.
1. Convert - First, figure out your weight in kilograms by dividing your weight in pounds by 2.2. To determine your height in centimeters, multiply your height in inches by 2.54. (Note: one inch = 2.54 cm and one kilogram = 2.2 lbs).
2. Calculate BMR - If you are a female, complete the following equation: 655 plus [9.6 multiplied by your weight in kilograms] plus [1.8 multiplied by your height in centimeters] minus [4.7 multiplied by your age in years] = "X." If you're a male, your equation is: 66 + [13.7 x weight in kg] + [5 x height in cm] - [6.8 x age in years]. "X" is your BMR.
Now, let's calculate your daily activities:
3. Add activity factor - Multiply X by one of the following activity factors:
A) 1.2 if you are sedentary - You do little or no activity. You sit in your room and watch TV all day. The thought of walking to class is overwhelming. Or, you might just have an injury.
B) 1.375 if you are slightly active. You do some light exercise one to three days per week. You might find yourself frequently reading a magazine while exercising. Or, you stand around all day doing lab work.
C) 1.55 if you are moderately active. You do moderate exercise three to five days per week. You enjoy a brisk walk at four mph, or you play a game of tennis. You are "one of those" who run around campus from class to class because you think you're still in high school.
D) 1.725 if you are very active. You perform strenuous exercise five to six days per week. You're on a varsity team, playing full court basketball or lacrosse.
E) 2.0 if you are extremely active. You're an animal, performing hard daily exercise six to seven days per week, sometimes training two times per day. You're currently training for the Boston Marathon or doing a competitive triathlon.
4. Then, multiply your figure by 1.1, which accounts for a 10 percent increase in your energy needs due to the thermic effect of food.
Once you have a fairly reliable estimate of your daily energy needs, you can then create a diet around a combo of foods you enjoy, with the nutrients you need. As you make these adjustments to your daily calorie intake, it's important to remember that you have a good balance of foods including carbohydrates, fats, proteins, vitamins, minerals, and water.
The next step is to adjust your calories according to your primary goal. The math part of calorie balance is simple: to keep your weight the same, calories in should equal calories expended. To lose weight, you need to create a calorie deficit by reducing your calories slightly below your maintenance level (or keeping your calories the same and increasing your activity above your current level).
To gain weight, you need to increase your calories above your maintenance level. The only difference between weight gain and weight loss programs is the total number of calories required.
You might need to experiment with your "calculated" needs, since metabolic rates of individuals vary. If it seems too low, you may need to up it a little, or if it seems too high, you may need to decrease a little.
Keep in mind that those numbers are only an estimate. Differences in caloric needs among individuals can vary greatly, and this is just the one-size-fits-all formula that gives most people a decent ballpark figure.
Senior Marissa Beck, an English and art history major, works with the Strong Women program as an assistant manager and personal trainer for the Tufts Personalized Performance Program. She can be reached at Marissa.Beck@tufts.edu. This column is written in conjunction with Emily Bergeron, R.D., the editor of the Daily's Balance section.
