By Devin Wicks
Copied from the University of California,
Berkeley website
A sensible approach to weight control has to include healthy eating and regular
physical activity, and like I tell my clients, “it’s all about calories in
versus calories out.” Before going further, it’s important to understand a few
basic concepts. The first and most important being that your body burns calories all day
– everyday – until your last day! Yes, you can lay in bed and burn calories.
Even as you sleep, your body burns calories doing all those important things – like
breathing, digesting food, etc. – that it needs to do to keep it up and running. The
next concept (and here’s where I flex my mathematical prowess – brace
yourselves) is that weight control for most people looks something like this:
Weight Loss: Calories In < Calories Out
Weight Maintenance: Calories In = Calories Out
Weight Gain: Calories In > Calories Out
Somewhere out there my high school algebra teacher is beaming with joy – this
one’s for you Mr. Quick! OK, now that we have the basic concepts down, let’s get
back to our discussion on sensible weight control. The key to sensible weight control is
getting a complete picture of your daily caloric needs, or your Total Daily Energy
Expenditure (TDEE). Arriving at your TDEE is a three step process.
Step One – Calculating your Basal Metabolic Rate
First we need to look at a number called your Basal Metabolic Rate (BMR) or the amount of
calories you use in a 24 hour period just being you. This is the minimum amount of
calories per day that your body needs to keep working, and does not take into account your
activity level (we’ll get to that later in step two). There are a number of ways to
determine your BMR, one is to calculate it using a common formula (darn…more math!):
Men: BMR = 66 + (13.7 X weight in kg) + (5 X height in cm) - (6.8 X age in years)
Men: BMR = 66 + (6.23 X weight in lbs) + (12.7 X height in inches) - (6.8 X age in years)
Women: BMR = 655 + (9.6 X weight in kg) + (1.8 X height in cm) - (4.7 X age in years)
Women: BMR = 655 + (4.36 X weight in lbs) + (4.57 X height in inches) - (4.7 X age in
years)
Note: 1 inch = 2.54 cm; 1 kilogram = 2.2 lbs
Step Two – Determining Your Activity Level
After calculating your BMR you’ll need to factor in your activity level to get your
TDEE. To do this, simply plug your BMR into the formula that best represents your average
workout week:
Sedentary = BMR X 1.2 (little or no exercise, desk job)
Lightly active = BMR X 1.375 (light exercise/sports 1-3 days/wk)
Mod. active = BMR X 1.55 (moderate exercise/sports 3-5 days/wk)
Very active = BMR X 1.725 (hard exercise/sports 6-7 days/wk)
Extra active = BMR X 1.9 (hard daily exercise/physical job/2X day training)
Step Three – Plug in the Numbers
Now we’ll plug in the numbers. Here’s an example of how to do that:
You are female
You are 30 yrs old
You are 5' 6 " tall (167.6 cm)
You weigh 120 lbs. (54.5 kilos)
Your BMR = 655 + 523 + 302 - 141 = 1339 calories/day
Your BMR is 1339 calories per day
Your activity level is moderately active (work out 3-4 times per week)
Your activity factor is 1.55
Your TDEE = 1.55 X 1339 = 2075 calories/day
Now What?
If you’ve done the math correctly, the number you’ve just calculated is the
amount of calories you need based on your current activity level to maintain your current
weight. Great, so I bet you’re asking, “Now that I have this information, what
do I do with it?”
Well, let’s say your goal is to gain muscle mass. Then you would want to slightly
increase your caloric intake (say 15% or 200-500 calories) with a healthy diet and follow
a well-designed strength training program.
Conversely, if your goal is to reduce body fat, then you would want a slight caloric
deficit (say the same 200-500 calories a day) coupled with a smart exercise program to
prevent muscle loss. By “slight”, I mean a small percentage – say 10-15% of
your BMR.
Reduce Your Calories Carefully
But before you run off and reduce calories – and this is where you need to pay
attention – you should know that if you cut your calories too much below your BMR you
run the risk of significantly slowing down your metabolism – something we don’t
want to do if your goal is to reduce body fat. How low is too low? On average, this point
tends to be around 15-20% below your BMR. Any lower than that and you can slow your
metabolic rate by up to 30%. To make matters worse, at this point your body will tend to
lose muscle mass, slowing your metabolic rate even further, making it harder to lose
weight and potentially leading to weight gain. This is one of the main reasons that people
who severely restrict their diets eventually begin to notice a slowing of weight loss and
an eventual rapid weight gain once they come off their calorie restricted diet. Let’s
take a look at our friend Joe and see what happened to him.
Joe’s Experience
Joe weighs 210 pounds, wears a size 35 pant and has 70 pounds of body fat with 140 pounds
of fat-free weight (muscle, bone, organs, water, etc.) Now, Joe is overweight and over fat
because his daily caloric intake is around 2900 calories but he burns only 2400 calories
according to his TDEE. To lose fat weight, he starts one of those low calorie, low
carbohydrate diets which restricts him to 1500 calories per day. He finds this strict diet
extremely difficult to follow, often feels irritable and hungry, and has trouble
maintaining energy throughout the day.
After twelve weeks of the strict dieting, he has achieved his goal of 170 pounds, and now
wears a 32 pant. To Joe, life is good. Confident that he can stop dieting and maintain his
new weight, Joe resumes his “normal eating habits.” However, this time he
restricts himself to 2200 calories per day.
Joe believes that this is a reasonable drop from the 2900 calories he used to eat.
Unfortunately, even 2200 calories are more than he now burns each day, based on his
“normal” activity. Joe does not realize that of the 40 pounds of weight he lost,
25 pounds came from fat-free mass otherwise known as muscle. By severely reducing his
daily caloric intake while on the diet, Joe reduced muscle mass and unwittingly lowered
his daily caloric requirement down to 1900. So his new intake of 2200 calories exceeds his
daily needs.
Soon Joe’s weight crept back up to 200 pounds and he is now wearing a size 36 pant.
Not only does he not have the slightest idea what happened, he feels more fatigued than
before, and tends to come down with more colds and infections, and generally feels washed
out.
The Fix
To prevent following in Joe’s foot steps, you need to approach weight control
sensibly with the idea that any change needs to happen gradually over the course of six
months to a year or more. It’s not advisable to make any drastic changes to your diet
all at once. After calculating your own total daily energy expenditure and adjusting it
according to your goal, make your adjustments gradual and plan on a weight change
happening over time – say, 1 or 2 pounds per week. Next, you want to include a smart
workout incorporating both cardiovascular training as well as strength training to ensure
a faster metabolism, higher energy and overall better health. And finally, make sure the
food you’re eating, your fuel, consists of a well-balanced diet that meets all of
your nutritional needs. I know this doesn’t sound nearly as sexy as those fabulous
diets that promise the world, but in the end this works!
Here are some interesting facts to keep in mind:
Happy dieting!