How to calculate the calories you need By Richard Diaz of Diaz Human Performance LLC. The first step in designing a nutrition plan is to calculate how many calories you burn in a day, your total daily energy expenditure (TDEE). TDEE is the total number of calories that your body expends in 24 hours, including all activities. TDEE is also known as your "maintenance level". Knowing your maintenance level will give you a starting reference point from which to begin your diet. According to exercise physiologists William McArdle and Frank Katch, the average maintenance level for women in the United States is 2000-2100 calories per day and the average for men is 2700-2900 per day. These are only averages; caloric expenditure can vary widely and is much higher for athletes. Calorie requirements may also vary among otherwise identical individuals due to differences in inherited metabolic rates.
The first step in designing a nutrition plan is to calculate how many calories you burn in a day; your total daily energy expenditure (TDEE). TDEE is the total number of calories that your body expends in 24 hours, including all activities. TDEE is also known as your "maintenance level". Knowing your maintenance level will give you a starting reference point from which to begin your diet. According to exercise physiologists William McArdle and Frank Katch, the average maintenance level for women in the United States is 2000-2100 calories per day and the average for men is 2700-2900 per day. These are only averages; caloric expenditure can vary widely and is much higher for athletes. Calorie requirements may also vary among otherwise identical individuals due to differences in inherited metabolic rates.
Methods of determining caloric needs
There are many different formulas you can use to determine your caloric maintenance level by taking into account the factors of age, sex, height, weight, lean body mass, and activity level. Any formula that takes into account your lean body mass (LBM) will give you the most accurate determination of your energy expenditure, but even without LBM you can still get a reasonably close estimate.
The "quick" method (based on total bodyweight)
An easy method to determine calorie needs is to use total body weight times a multiplier.
Weight loss = 12 -13 calories per lb. of bodyweight
Maintenance = 15 -16 calories per lb. of bodyweight
Weight gain: = 18 -19 calories per lb. of bodyweight
This is a very easy way to estimate caloric needs, but it doesn’t take into account activity levels or body composition, the more lean body mass one has, the higher the TDEE will be. Because body fatness is not accounted for, this formula may greatly overestimate the caloric needs if someone is extremely over fat. Muscle is metabolically active tissue, and it requires energy just to sustain it, one way to increase your metabolism is to weight train to increase and/or maintain lean body mass.
Katch-McArdle formula (BMR based on lean body weight)
If you have had your body composition tested and you know your lean body mass, then you can get a pretty accurate BMR. The Katch & McArdle formula takes into account lean mass and is more accurate than a formula based on total body weight. Since this formula accounts for LBM, this single formula applies equally to both men and women.
BMR (men and women) = 370 + (21.6 X lean mass in kg)
Example: You are female, you weigh 120 lbs. (54.5 kilos) your body fat percentage is 20% your lean mass is 96 lbs. (43.6 kilos) BMR = 370 + (21.6 X 43.6) = 1312 calories to determine TDEE from BMR, you simply multiply BMR by the activity multiplier:
Example: Your BMR is 1312, your activity level is moderate (work out 3-4 times per week)
your activity factor is 1.55, your TDEE = 1.55 X 1312 = 2033 calories
The primary benefit of factoring lean body mass into the equation is increased accuracy when your body composition leans to either end of the spectrum (very muscular or very obese).
Adjust your caloric intake according to your goal
Once you know your TDEE, the next step is to adjust your calories according to your primary goal. The mathematics of calorie balance is simple: To keep your weight at its current level, you should remain at your daily caloric maintenance level. 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 programs and weight loss programs is the total number of calories required.
Negative calorie balance is essential to lose body fat.
If you are eating more calories than you expend, you simply will not lose fat, no matter what type of foods or food combinations you eat. Some foods get stored as fat more easily than others, but too much of anything, even "healthy food," will get stored as fat. You cannot override the laws of thermodynamics and energy balance. You must create a calorie deficit to burn fat. This will force your body to use stored body fat to make up for the energy deficit. There are 3500 calories in a pound of stored body fat. If you create a 3500-calorie deficit in a week through diet, exercise or a combination of both, you will lose one pound. If you create a 7000 calories deficit in a week you will lose two pounds. The calorie deficit can be created through diet, exercise or preferably, with a combination of both.
Calorie deficit thresholds: How low is too low?
It is well known that cutting calories too much slows down the metabolic rate, decreases thyroid output and causes loss of lean mass, so the question is how much of a deficit do you need? There definitely seems to be a specific cutoff or threshold where further reductions in calories will have detrimental effects. The most common guideline for calorie deficits for fat loss is to reduce your calories by at least 500, below your maintenance level. The American College of Sports Medicine (ACSM) recommends that calorie levels never drop below 1200 calories per day for women or 1800 per day for men, these calorie levels are extremely low. A larger deficit may be necessary in some cases, but the best approach would be to keep the calorie deficit through diet gradual while increasing activity level.
Example 1: Your weight is 120 lbs., your TDEE is 2033 calories
Your calorie deficit to lose weight is 500 calories, optimal caloric intake for weight loss is 2033 - 500 = 1533 calories
Example 2: Your calorie deficit to lose weight is 20% of TDEE (.20% X 2033 = 406 calories)
Your optimal caloric intake for weight loss = 1627 calories
Adjust your caloric intake gradually
After calculating your total daily energy expenditure and adjusting it according to your goal, if the amount is substantially higher or lower than your current intake, then you may need to adjust your calories gradually. For example, if your determine that your optimal caloric intake is 1900 calories per day, but you have only been eating 900 calories per day, your metabolism may be sluggish. An immediate jump to 1900 calories per day might actually cause a fat gain because your body has adapted to a lower caloric intake and the sudden jump up would create a surplus. The best approach would be to gradually increase your calories from 900 to 1900 over a period of a few weeks to allow your metabolism to adapt.
Measure your results and adjust calories accordingly
These calculations for finding your correct caloric intake are quite simplistic and are just estimates to give you a starting point. You will have to monitor your progress closely to make sure that this is the proper level for you. You will know if you’re at the correct level of calories by keeping track of your caloric intake, your bodyweight, and your body fat percentage. You need to observe your bodyweight and body fat percentage to see how you respond. If you don’t see the results you expect, then you can adjust your caloric intake and exercise levels accordingly. The bottom line is that it’s not effective to reduce calories to very low levels in order to lose fat. In fact, the more calories you consume the better, as long as a deficit is created through diet and exercise. The best approach is to reduce calories only slightly and raise your daily calorie expenditure by increasing your frequency, duration and or intensity of exercise.
Clinical Assessments and Meal Planning
In our day-to-day operation we provide metabolic analysis via computer assisted gas analyzers. This is a special device that acts much like a smog check for your car. It reads air intake (O2) and gas exhaust (CO2) from which these samples provide a “RQ” or respiratory quotient. Armed with this data we can determine a.) How many calories you require a rest and b.) At what heart rate will you burn calories from fat most efficiently? For more information on meal planning or assessment services, please visit us at diazhumanperformance.com
References:
1. Katch, Frank, Katch, Victor, McArdle, William. Exercise Physiology: Energy, Nutrition, and Human Performance, 4th edition. Williams & Wilkins, 1996.
2. Whitney, Eleanor, Rolfes, Sharon. Understanding Nutrition, 8th Edition, Wadsworth Publishing, 1999.
3. American College of Sports Medicine. Position Statement on proper and improper weight loss programs. Medicine and Science in Sports and Exercise 15: ix - xiii, 1983.
4. McDonald, Lyle. The Ketogenic Diet. Morris Publishing. 1998
Mr. Richard Diaz founded Diaz Human Performance LLC, in January of 2000. The focus of this business was and remains, to serve performance-training advice, consultation and diagnostic assessments for athletic achievement. DHP features a host of diagnostic assessments designed to enhance physical performance be it team sport, endurance achievement, and general fitness or weight loss.
Over the past 16 years Mr. Diaz has owned and operated 4 independent fitness operations in where he was solely responsible for the development of training principles, programs and business development.
Author’s website www.diazhumanperformance.com
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