Saturday, July 25, 2009
Before we set calories and gure out correct amounts for proteins, fats and carbs, it’s important to understand where the calories go when we eat. Understanding what happens to the calories in metabolism helps us make smart decisions about what we should be eating for a particular goal, such as losing or gaining weight.
There is a strong synergism between the foods we eat and our perfor-
mance, muscle mass and body fat levels. People debate (make that ght!)
about every aspect of nutrition: high carb vs. low carb diets, high protein
diets, high fat diets vs. low fat diets, and so on.
Regardless of which diet a person follows, one element always remains a
constant: the concept of energy balance. The energy balance equation can
be summed up as:
Energy Intake = Energy Expenditure + Energy Storage.
It does not matter if your goal is to lose, maintain or gain body weight.
Everything ultimately revolves around this simple equation. The type and
ratios of macronutrients we eat matters as well as the total number of calo-
Brink’s Universal Law of Nutrition states: “Total calories dictate how much
you lose or gain, and macronutrient types and ratios dictate what you lose
To better understand energy balance, we must rst be familiar with the
components of energy expenditure. Total daily energy expenditure ( TDEE,
which is the average number of calories one oxidizes or “burns” in a day)
can be partitioned into three components:
• Resting metabolic rate (RMR)
• Thermic e ect of a meal ( TEM)
• Energy expenditure of physical activity (EEPA)
Return to T.O.C.
“ Brink’s Univer-
sal Law of Nutri-
tion states: ‘Total
how much you lose
or gain, and mac-
and ratios dictate
what you lose or
Resting Metabolic Rate (RMR)
Chapter 2/Where Does The Food Go? Understanding TDEE
RMR makes a major contribution to TDEE and is associated with the energy
cost of maintaining physiological homeostasis.
This includes the energy cost of maintaining body temperature, cardiac
output, respiration, nervous system function and other involuntary activi-
This component of energy expenditure is in uenced by body fat levels,
gender, and physical tness, but is determined primarily by lean body mass.
Therefore, the greater the amount of lean body mass that you have at any
given body weight, the greater your caloric expenditure - even at rest.
Your metabolism is the rate at which your body oxidizes (burns) calories
to live. About 10 percent of your total daily energy expenditure is used to
convert the food you eat into fuel or blubber (fat). Another 20 percent or
so is accounted for by exercise and the everyday physical activities of life. I
don’t believe these gures are written in stone, but you can get an idea of
where the calories you eat are going, at least.
However, the biggest block of energy is consumed by your resting meta-
bolic rate (RMR), which accounts for up to 75 percent of your daily expen-
With the RMR accounting for this big a chunk of your daily calories, it be-
hooves you to focus on the RMR as a key spot to manipulate. For example,
people who are naturally blessed with a higher RMR will burn up to 200
calories more each day, even when they perform identical activities.
Can the RMR be altered? Of course! Your RMR is ultimately controlled by
your genetic makeup; but age, gender and body composition also play an
important role. Altering your body composition by increasing your muscle
mass and decreasing body fat will increase RMR.
The reader may be thinking, “how do I increase my RMR?” Fortunately,
when it comes to altering your RMR, nothing beats weight training.
over aerobics any day. Several recent studies have con rmed that resis-
tance training maintains resting metabolic rate (RMR) better than aerobics.
Studies have shown, as well, that resistance training is far superior to aero-
bics for maintaining the metabolically active tissue we need (muscle!) for a
superior fat burning metabolism, while trying to gain muscle mass.
Weight lifting is the best exercise you can do to keep your metabolism el-
evated over long periods of time. Resistance training burns approximately
the same number of calories as running or hopping around in an aerobics
class, but - unlike aerobics - the calorie burning and metabolism raising ef-
fects of weight training continue long after the activity has ended.
Aerobic exercise can never o er that bene t. After aerobic exercise, RMR
returns to normal within an hour or so, resulting in the consumption of a
few additional calories. Big deal. After weight lifting, RMR remains elevated
for up to 15 hours! The bottom line: weight training increases post-exercise
metabolism and builds muscle that is far more metabolically active than
OK, back to the energy equation and understanding TDEE.
Thermic Effect of a Meal (TEM)
TEM is the energy increase that takes place after you eat a meal containing
protein, carbohydrate, fat and alcohol.
The increase in energy expenditure is due to the cost of digestion, absorp-
tion, mobilization and storage of these macronutrients. On average this
component comprises approximately 10 percent of TDEE. Perhaps most
importantly, the thermic response to ingested foods is driven primarily by
the ratio of macronutrients.
In other words, the thermic e ect of the meal can vary widely, depending
on the ratio of carbs, fats and proteins in a given meal. While both protein
and carbohydrate will elicit notable and signi cant thermic responses, fat
does not. This is one of several reasons why higher fat diets have been
blamed for increased body fat levels over the years.
However, as mentioned throughout this chapter, the e ects that fats have
on body fat are complicated, since certain fats are helpful for reducing body
fat, blocking fat storage, and for increasing beta-oxidation, etc. Though
“ After aerobic
returns to normal
within an hour or
so, resulting in the
a few additional
calories. Big deal.
After weight lift-
ing, RMR remains
elevated for up to
15 hours! Bottom
line, weight train-
ing builds muscle
that is far more
tive than fat.”
the e ect of fat on TEM is important to know, it’s even more important - in
my view - to remember that not all fats are created equal in terms of their
e ects on metabolism.
To conclude TEM, it can be stated that TEM varies according to the mixture
or ratio of macronutrients eaten at a given meal and can be manipulated
– to either increase or decrease TDEE – by altering the composition of the
Energy Expenditure of Physical Activity (EEPA)
EEPA is the most variable component of TDEE. Translated, it’s up to us to be
either couch potatoes or gym rats! EEPA is composed of both involuntary
(i.e., shivering) and voluntary muscular activity, such as exercise.
EEPA is in uenced somewhat by body weight and composition. This
means a heavier person will require more energy than a lighter person and
a leaner person will require more energy than a fatter counterpart of the
same weight for the same activity and intensity.
However, EEPA is primarily driven by an individual’s desire and ultimate
performance of activity, which is how hard they bust their butt on a par-
Putting the TDEE Together
Finally, we can now equate a person’s caloric needs as:
TDEE = RMR + TEM + EEPA
The TDEE can help us - not just to understand what our metabolisms do
with the foods we eat - but to ne-tune our diets to achieve our goal of
either gaining weight or losing it. If your TDEE exceeds calorie intake, you
lose weight. If your calorie intake exceeds TDEE (i.e. you are eating more
calories than you are “burning”) you will gain weight.
The real question is: what will that gained weight be? Fat? Muscle? Ulti-
mately what you gain or lose will be dependent on the ratio of macronutri-
ents, exercise choices, and genetics.