2. INTRODUCTION
• Energy is defined as the capacity of a physical system to
perform work.
• Energy is delivered to the body through the foods we eat and
liquids we drink.
• Foods contain a lot of stored chemical energy; when you eat,
your body breaks down these foods into smaller components
and absorbs them to use as fuel.
• Energy comes from the three main nutrients carbohydrates,
protein, and fats, with carbohydrates being the most
important energy source.
• In cases where carbohydrates have been depleted, the body
can utilise protein and fats for energy. Your metabolism is the
chemical reactions in the body’s cells that change this food
into energy.
3. ENERGY CONVERSION IN HUMANS
• All living organisms, are
energy conversion machines.
• Conservation of energy
implies that the chemical
energy stored in food is
converted into work, thermal
energy, and/or stored as
chemical energy in fatty
tissue.
• The fraction going into each
form depends both on how
much we eat and on our level
of physical activity.
• If we eat more than is needed
to do work and stay warm, the
remainder goes into body fat.
4. ATP SYNTHESIS
• The human body carries out its main functions by
consuming food and turning it into usable energy.
Immediate energy is supplied to the body in the
form of adenosine triphosphate (ATP).
• Since ATP is the primary source of energy for
every body function, other stored energy is used
to replenish ATP.
• There are only small amounts of ATP in the body
so it is necessary to have sufficient energy stores
for backup.
5. BASAL METABOLIC RATE
• Most of the energy the body needs is for being at
rest, known as the Basal Metabolism.
• This is the minimum amount of energy the body
requires to maintain its vital functions such as
breathing, circulation and organ functions.
• The rate at which energy is utilised for such
functions is known as the Basal Metabolic Rate
(BMR) and varies based on genetics, sex, age,
height and weight. Your BMR drops as you get
older because muscle mass decreases.
6. UNITS OF ENERGY
• The SI unit of energy, work, and heat is the joule (J).
• A joule is a tiny amount of energy.
• One joule is equal to 1kg*m^2*s^-2.
• A kilo-joule (kJ) is equal to 1000 joules of energy.
• The calorie is used in nutrition to express the energy
content of foods. However, because a calorie is a rather
small quantity, nutritional energies are usually expressed in
kilocalories (kcal), also called Calories (capitalized; Cal).
• Calorie (Cal) is used to denote energy stored inside the
food or energy used by the body.
• 1 Cal is equal to 4.184 Joules.
• Similarly, a kilo-calorie (KCal) is equal to 1000 calories.
• 1 cal = 4.184 J
7. ENERGY REQUIREMENT
• The amount of food energy needed to balance
energy expenditure in order to maintain body
size, body composition and a level of necessary
and desirable physical activity consistent with
long-term good health.
• This includes the energy needed for the optimal
growth and development of children, for the
deposition of tissues during pregnancy, and for
the secretion of milk during lactation consistent
with the good health of mother and child.
8. ENERGY EXPENDITURE
• Energy expenditure is the
amount of energy that a
person needs to carry out
physical functions such as
breathing, circulating blood,
digesting food, or exercising.
Energy is measured in
calories, and your total daily
energy expenditure (TDEE) is
the number of calories you
burn each day. To prevent
weight gain, energy intake
must be balanced with
energy expenditure.
• Our TDEE is essentially
comprised of three
components:
• Resting metabolic rate (RMR):
the energy required to keep your
body functioning at rest
• The thermic effect of food (TEF):
the energy cost of chewing,
swallowing, digesting, absorbing
and storing food
• The thermic effect of physical
activity (TEPA): the energy of
activity (e.g., exercise, physical
activity) and non-exercise
activity thermogenesis (NEAT).*
9. TOTAL METABOLIC RATE
The total metabolic rate is the amount of energy
used by the body in carrying out all of its activities.
It is often expressed in kilojoules per day.
The factors that determine the total metabolic rate
are:
• resting metabolic rate
• the energy needed to do all kinds of muscular
work, from sitting up in bed to very strenuous
physical labour or exercise
• the thermic effect of food.
10. RESTING METABOILIC RATE
• Resting metabolism is the energy required by your
body to perform the most basic functions when your
body is at rest.
• These essential functions include things like breathing,
circulating blood or basic brain functions.
• RMR is often used interchangeably with basal
metabolic rate (BMR).
• However, while your RMR refers to the number of
calories your body burns while at rest, your BMR is the
minimum number of calories your body burns to just
exist, without any external influences.
11. RESTING METABOILIC RATE
CALCULATION
• A relatively simple way of determining resting
metabolic rate is to use an equation known as the
Mifflin equation. It is based on body mass (w), height
(h), age (a) and sex.
• Although it does not take ethnicity or amount of fat
tissue to lean tissue into account, it is still a good
predictive measure.
• The formula is:
• Males: RMR = (10 x w) + (6.25 x h) - (5 x a) + 5
• Females: RMR = (10 x w) + (6.25 x h) - (5 x a) - 161
• For a teenage boy of body mass 60 kg, height 165 cm,
age 14 years:
12.
13. THERMIC EFFECT OF FOOD (TEF)
• Specific dynamic action (SDA), also known as thermic
effect of food (TEF) or dietary induced thermogenesis
(DIT).
• The thermic effect of food (TEF) is the amount of
energy it takes for your body to digest, absorb, and
metabolise the food you eat.
• TEF makes up a part of your daily calorie expenditure
(calories out), and usually represents about 10% of the
caloric intake of healthy adults eating a mixed and
balanced diet. So for example, if you expend 2000
calories in a day, around 200 of those will be burned
just from eating food.
14. MACRONUTRIENTS- TEF
• The energy required to digest each macronutrient (its
TEF) is measured as a percentage of the energy
provided by it.
• Fat provides 9 calories per gram. Its TEF is 0-5%
• Carbohydrate provides 4 calories per gram. Its TEF is 5-
15%
• Protein provides 4 calories per gram. Its TEF is 20-30%
• So that means protein tops the charts as the most
thermic macronutrient, with approximately 25-30% of
the calories you consume from protein being used for
digestion and metabolism.
15. MACRONUTRIENTS- TEF
• Carbohydrates are the next most thermic
macronutrient, with a TEF of 5-15% depending on
the carb source. There’s a reason we recommend
complex carbs on our nutrition plans to give you
sustained energy for your personal training
sessions and throughout the day.
• High fibre carbs digest more slowly and have a
higher thermic response, packing in more
nutrients and vitamins along the way.
16. MACRONUTRIENTS- TEF
• Dietary fats have the lowest thermic effect at
approximately 5-10% and are the simplest to digest.
That doesn’t mean you shouldn’t include fats in your
diet – it’s just a case of choosing the right ones.
• Fats play a vital role in maintaining healthy skin, hair
and nails, protecting vital organs against shock and
helping maintain body temperature. They can also be
used as an energy source, and slow down the body’s
insulin response to high sugar foods.
• Good sources of fat to include in your diet are avocado,
salmon, nuts, egg yolks and pumpkin seeds.
17. THERMIC EFFECT OF PHYSICAL ACTIVITY
• The thermic effect of physical activity (TEPA) is the
amount of energy burned during all physical activity,
which includes everything from standing up from a
seated position to the most intense high-intensity
interval training workout (and everything in between).
TEPA can range anywhere from 15 to 30% of TDEE.
• TEPA includes both exercise, which is a specific,
planned physical activity, and non-exercise activity
thermogenesis (NEAT), which includes the energy cost
of normal daily functions like walking the dog, cleaning
the house or walking up stairs. Increasing the amount
of NEAT can help burn up to an additional 300 calories
per day, which is about the equivalent of a 3-mile run.
18. BALANCING ENERGY IN AND ENERGY
OUT
• Balancing energy intake by eating food with
output through resting metabolism, growth,
exercise and digesting food is one of the key
components of maintaining health and
wellbeing.
