This document discusses lipids and basal metabolic rate (BMR). It defines BMR as the minimum amount of energy needed to sustain essential body functions at rest. Key factors that affect BMR include age, gender, pregnancy, exercise level, hormones, stress, nutrition, and environment. BMR can be measured directly through calorimetry or indirectly by measuring oxygen consumption. The document also explains the importance of lipids from a nutritional perspective and how saturated, unsaturated, and trans fats impact health risks like diabetes and heart disease. Replacing saturated fats with mono- or polyunsaturated fats can lower blood triglycerides and cholesterol.

1. Nutritional Importance of Lipids
& BMR
By
Dr Khaled Saleh Algariri
June 2014

2. Basal Metabolic Rate (BMR)
 Basal Metabolic Rate (BMR) is the rate of energy
expended by animal (such as human) bodies when at
rest.
 This is the minimum amount of energy needed by the
organism to perform essential functions such as
breathing (and associated movements), heartbeat and
blood circulation, synthesis of molecules e.g. proteins,
maintenance of ion gradients across membranes, etc..
Another way to describe this is energy that is just
sufficient for the functioning of the body's tissues and
vital organs.

3.  Definition of Metabolic Rate
Metabolic rate is the energy used by the body in the
performance of its normal functions including both
maintaining the body itself (replacing tissues, etc.)
and using the body to perform external functions e.g.
physical work, sports and daily tasks.
Basal Metabolic Rate (BMR)

4. What is meant by "at rest" ?
BMR is measured:
When the subject (e.g. a person) is lying still, i.e. not
making physical movements
When the subject (e.g. a person) is quiet, i.e. not talking or
otherwise under mental stress
In a room that is comfortably warm - so that the body
does not need to adjust body temperature
Approx. 12-18 hours after the subject's most recent meal,
so that energy is not being used for digestion and
absorption of food (which can require significant energy).
Basal Metabolic Rate (BMR)

5. BMR can be expressed in units of kJ per square metre
of body surface area per hour.
This can be written as kJ / m2 / h or kJ m-2 h-1.
Basal Metabolic Rate (BMR)

6. Main Factors affecting BMR:
1- Age -
BMR decreases as ages increases because:
 The proportion of lean body mass decreases as age increases
 The synthesis of molecules such as proteins decreases as age
increases.
2- Gender (male or female) -
 Males usually have a higher BMR than females (of the same age)
because males tend to have a higher proportion of lean body mass than
females of the same age. Conversely, females tend to have a higher
proportion of fat cells and fat cells have a lower metabolic rate than
lean muscle cells.
3- Pregnancy -
 BMR increases during pregnancy and lactation due to the high energy
requirement of producing foetal tissues and then breast milk.
Basal Metabolic Rate (BMR)

7.  Other factors that increase BMR:
1-lncreased intake of foods -
 Eating large amounts of food requires the digestive system to
process more material which therefore requires more energy.
(However, as food is the source of the body's energy any resulting
increase in BMR is likely to be less than the increase in energy
intake due to the additional consumption of food.)
2-lncreased secretion of certain hormones -
 The thyroid hormones triiodothyronine (T3) and thyroxine
(T4) are the main regulators of BMR. BMR increases when the
quantity of these hormones in the blood increases. Some other
hormones such as testosterone, insulin and human growth
hormone (HGH) can also increase the body's metabolic rate.
)
Basal Metabolic Rate (BMR)

8. 3-Increased physical exercise -
 Exercise requires and uses energy. Although BMR is
energy expended at rest, exercise has both short-
term effects (during the time of the exercise itself) and
long-term effects (after and between exercise sessions).
One of the longer term effects of frequent physical
exercise is an increase in BMR. This is due to increased
overall activity of the heart and vascular system,
together with other body systems and tissues.
Basal Metabolic Rate (BMR)

9. 4-Environmental conditions -
 e.g. extremes of temperature. If/when body temperature
increases above or decreases below its ideal range,
mechanisms within the body act to reduce or raise its
temperature to preserve health (and ultimately life - as
prolonged elevated body temperature can destroy proteins
within the body and prolonged depressed temperatures can
cause cardiac arrhythmias - which can be fatal in both
cases). In general, the higher the body temperature the
higher the metabolic rate, hence metabolic rate is higher
when a person has a fever.
Basal Metabolic Rate (BMR)

10. 5-Increased stress and anxiety -
 Stress is sometimes thought of as an unpleasant
combination of overwhelming worry, anxiety, fear and the
feelings of constraint and helplessness. Such emotions are
associated with physical responses within the body which
vary but may include e.g. increased heart rate or blood
pressure, difficulty sleeping, nausea, abdominal
discomfort, increased sweating, etc.. To the extent that
these involve (e.g. increased heart rate), cause (e.g.
difficulty sleeping) or are caused by (e.g. nausea,
abdominal issues) increased bodily function and so
increased use of energy, BMR increases accordingly.
Basal Metabolic Rate (BMR)

11.  Other factors that decrease BMR:
1-Malnutrition -
 If the body is not supplied with sufficient energy and nutrients in the
form of solid food and liquids (water, drinks, soups, etc.) it becomes
unable to support the body by performing all necessary functions as
effectively as if supplied with those. When the body is not sustaining
itself and e.g. replenishing worn-out tissues effectively, it tends to use
less energy than when supplied with the dietary resources to do so.
2-Fasting -
 During fasting the digestive system does not expend energy processing
foodstuffs at each stage of the alimentary canal. The body's energy
requirement is therefore adjusted to be lower during fasting than at
times of regular eating.
3-Sleep -
 The body uses less energy during sleep than when awake. The
proportion of time a person spends sleeping can affect his or her BMR.
Basal Metabolic Rate (BMR)

12.  Measurement of Basal Metabolic Rate (BMR)
1-Direct calorimetry
The heat released from the body of a person who is
resting, e.g. lying still on a comfortable surface or
mattress, while breathing normally is used to increase
the temperature of circulating water.
The resulting increase in the temperature of the water
is proportional to the BMR of the person.
Basal Metabolic Rate (BMR)

13. LIPIDS
2-Indirect calorimetry
While a person rests lying still on a comfortable surface or
mattress, a respirometer is used to measure his or her
oxygen consumption. His or her BMR is then calculated
from the volume of oxygen he or she used according to:
 BMR (in kJ/m2/h) = [volume of oxygen gas used (in dm3)]
x 18
 This formula applies because it has been found that the
average human adult typically releases 18 kJ of energy (heat
energy) per 1x dm3 of oxygen used by the body.
 Average BMR: 70 C/hr or 1680 C/day

14. Why are lipids important from a nutritional
perspective ?
• Blood free fatty acids-if elevated concentration
then greater risk of type II diabetes.
•Blood triglycerides – if elevated concentration
then greater risk of heart disease.
•Blood cholesterol- if elevated concentration
then greater risk of heart disease
LIPIDS

15.  Fatty acids can be Saturated or Unsaturated,
Monounsaturated, or polyunsaturated & Trans-fatty
acids
LIPIDS

16. LIPIDS
 Animal fats are high in saturated fatty acids
 Vegetable fats are high in unsaturated and
polyunsaturated fatty acids
 Trans fatty acids are manufactured fats created during
a process called hydrogenation, which is aimed at
stabilizing polyunsaturated oils to prevent them from
becoming rancid and to keep them solid at room
temperature. They may be particularly dangerous for
the heart and may pose a risk for certain cancers.
Hydrogenated fats are used in stick margarine, fast
foods, commercial baked goods (donuts, cookies,
crackers), processed foods, and fried foods.

18. LIPIDS
Saturation
 Saturated fatty acid – carbon chains
filled with hydrogen atoms (no C=C
double bonds)
1. Saturated fat – triglyceride
containing 3 saturated fatty
acids, such as animal fats
(butter, lard) .
2. Appear solid at room temperature

19.  Unsaturated fatty acid – carbon chains lack some
hydrogens (>1 C=C double bond)
1. Monounsaturated fat – triglyceride
containing fatty acids with 1 double
bond; i.e. canola & olive oil
2. Polyunsaturated fat- triglycerides
containing a high % of fatty acids with
>2 double bonds; i.e. corn, safflower,
soybean, sunflower oils and fish;
3. Appear liquid at room temperature
LIPIDS

20. Oleic acid – 18-carbon, monounsaturated
Linoleic acid – 18-carbon, polyunsaturated

21. LIPIDS
 Essential fatty acids – 2 polyunsaturated
fatty acids that must be provided in diet
1. Linoleic & Arachidonoic– omega-6
fatty acids and Linolenic – omega-3 fatty
acid
2. Founds in plant oils, nuts, seeds, whole
grains and fish
3. Play a role in normal growth &
development and may prevent heart
disease, hypertension, arthritis &
cancer

22. Eicosapentaenoic
and
Docoahexaenoic
acids

23. CHOLESTROL
Cholesteryl esters are composed of a single fatty acid
esterfied to cholesterol, in which the polar component
is an alcohol.
Cholesterol is a major component of all cell membranes.
It is required for synthesis of sex hormones, bile acids,
steroid hormones and vitamin D.
Dietary cholesterol is found only in foods derived from
animals (meat, fish, poultry, eggs and dairy products); it
is not present in plants.
LIPIDS

24. Sources of dietary cholesterol
Richest All offal, pat?, egg yolk, fish roes, mayonnaise
and shell fish.
Moderate Fat on meat, duck, goose, cold cuts, whole milks,
cream, ice cream, cheese, butter and most
commercially made cakes, biscuits and pastries.
Poor All fish and fish canned in vegetable oil, very
lean meats, poultry without skin, skimmed milk,
low fat yoghurt and cottage cheese.
Cholesterol free All vegetables, and vegetable oils, fruit
(including avocados and olives), nuts, rice, egg
white and sugar.

25. Eating lipids
-it’s a good news/bad news story
Saturated fats (12, 14 and 16 carbon fatty
acids are the really bad ones in terms of
raising concentrations of bad cholesterol)

26. Eating lipids
-it’s a good news/bad news story
Trans fats-lower good cholesterol and
raise bad cholesterol in the blood plasma

27. Eating lipids
-it’s a good news/bad news story
Replacing saturated fats with monounsaturated fats
lower concentrations of blood plasma triglycerides,
cholesterol and bad cholesterol

28. Eating lipids
-it’s a good news/bad news story
Replacing saturated fats with polyunsaturated fats
lower concentrations of blood plasma triglycerides,
cholesterol and bad cholesterol

29. Copyright 2005 Wadsworth Group, a division of Thomson Learning

30. Thank you