1. 4-Fats and Exercises
Nutrition and Fitness
Prepared by
Dr. Siham Gritly
Dr. Siham Gritly

2. Lipids and fats
• Introduction;-
• *Lipids are chemical compound naturally
occurring substance; consist of carbon,
hydrogen, and oxygen, widely found in plant
and animal kingdoms. main foods contributing
fats to our diet are butter, margarine, lard,
vegetable oil, fat of meat, cream, milk, milk
product, egg yolk, fish, poultry, nuts, seeds,
olives, whole grain cereals.
Dr. Siham Gritly

3. • A molecule of dietary fat consists of several
fatty acids (containing long chains of carbon
and hydrogen atoms), bonded to a glycerol.
They are typically found as triglycerides
(three fatty acids attached to one glycerol
backbone).
• Fats may be classified as saturated or
unsaturated depending on the structure of the
fatty acids involved.
Dr. Siham Gritly

4. exercise;
discus role of Bile salt and fat digestion
Dr. Siham Gritly

5. major functions of lipids in human body;
• *main source of energy, provide the body with 2/3
of energy (9 kal)
• *main source of fat soluble vitamins A, K, E D
• *protection against traumatic injury an shock
• *maintain body temperature
• *provide pleasant feeling of satiety after a meal
• *add to the palatability to diet
• *help in formation of tissues and other important
organs in the body such as brain and bone marrow
Dr. Siham Gritly

6. Classification of fats according to National
Academy of Sciences
• Total fat, provide 20-35 % of total energy intake
• Saturated fatty acids, risk of (Coronary Heart
Disease CHD) milk fat, coconut
• Cis monounsaturated fatty acids, (olive oil) prevent
(CHD), peanut oil
• Cis polyunsaturated fatty acids of two type health
benefit; fish oil, sunflower oil, corn oil, fish oil
• 1-Omega 6 fatty acids
• 2-Omega 3 fatty acids
• Trans fatty acids, risk of (CHD), margin, shortening
Dr. Siham Gritly

7. Exercise;
• discus the role of liver in fat
metabolism
Dr. Siham Gritly

8. Lipids and fats present in the body in three different
forms
• 1-neutral fats (triglycerides)
• 2-cholesterol (present only in animal origin)
• 3-phospholipids (largest lipid components in
the body)
Dr. Siham Gritly

9. 1-Triglycerides or neutral fat
• Triglycerides are the main dietary fats in
human body. Triglycerides are alcohol glycerol
and three fatty acids. The main fatty acids ;
• 1-stearic acid a (saturated fatty acid)
• 2-oleic acid (unsaturated one double bond,
olive)
• 3-palmitic acid (saturated, poultry, beef, milk,
palm oil)
Dr. Siham Gritly

10. 2-Cholesterols
• *Are member of groups called sterols, it is alcohol
found only in tissues and cells of animals' origin.
• *main function of cholesterol;
• It enter in the formation of bile acids,
• *Essential component of the structural membranes of
all cells especially brain and nerve cells
• *They form a part of certain enzymes
• *Enter in the formation of steroid hormones such as
esterogens, progesterone and testosterones
• *Enter in the formation of vitamin D.
Dr. Siham Gritly

11. 3-phospholipids
• *phospholipids are any lipids containing
phosphorus. they are the largest lipid components
of the body after triglycerides
• *they form in all cells of the body
• *in plasma, they are present in combination with
proteins and lipoproteins, which evolved in
transport of fat and cholesterol
• *they form part of certain enzymes
• *main constituents of all cell membranes
Dr. Siham Gritly

12. • *example of phospholipids in the body;
• -lecithin; neurotransmitter consist of glycerol, fatty
acids, phosphoric acid and cholin (nitrogen-containing
base). found in liver, egg yolk, soy beans. the main
function; transport and utilization of fatty acids with the
action of enzyme as well as it prevent mental
retardation.
• *cephalins; for blood clotting (thromboplastin)
• *sphingomyelins; nerve tissues and brain, function act
as insulator around the verve fibers, found in egg yolk,
liver.
• *glycolipids; serve tissues, cell membranes and help in
fat transport.
Dr. Siham Gritly

13. Fats and exercise
• *Fat is a great fuel for or survival but it is not
adequate for high intensity exercise therefore fat
is essential for longer, slower lower intensity
and endurance exercise such as cycling and
walking.
• *If exercising at a low intensity and enough
stored fat available to fuel activity for hours or
even days as long as there is sufficient oxygen to
allow fat metabolism to occur.
Dr. Siham Gritly

14. • *As exercise strength increases, carbohydrate
metabolism takes over. It is more efficient than
fat metabolism, but has limited energy stores.
• This stored carbohydrate (glycogen) can
fuel about 2 hours of moderate to high level
exercise.
• After that, glycogen depletion occurs (stored
carbohydrates are used up) and if that fuel
isn't replaced athletes performance may
impaired
Dr. Siham Gritly

15. • When carbohydrate intake is depleted,
oxidation of fatty acids accelerate to provide
energy through the production of acetyl CoA
(TCA substrate)
Dr. Siham Gritly

16. Using fat for fuel for exercise,
Some factors might affect using fat as fueling
intense exercise
• 1-Fat is slow to digest and be converted into a
usable form of energy but it can take up to 6
hours.
• 2-Converting stored body fat into energy takes
time. The body needs to breakdown fat and
transport it to the working muscles before it can
be used as energy.
Dr. Siham Gritly

17. • 3-Converting stored body fat into energy takes
a great deal of oxygen,
• -For these reasons, athletes need to carefully
time when they eat fat, how much they eat and
the type of fat they eat. In general, it’s not a
great idea to eat fat immediately before or
during intense exercise
Dr. Siham Gritly

18. Fat metabolism during exercise
• *People store large amounts of body fat in the
form of triglyceride within adipose tissue as
well as within muscle fibers.
• *These stores fat must be metabolize into FFA
and transported to muscle mitochondria for
oxidation during exercise.
Dr. Siham Gritly

19. lipolysis (breakdown of lipids)
Energy utilization from Triglycerides (lipolysis)
• *for energy utilization, triglycerides
breakdown or hydrolysis by the action of
enzyme to fatty acids and glycerol, transport to
the active tissues for oxidation to energy.
• *The glycerol released from this reaction is
water soluble and diffuses freely into the blood
Dr. Siham Gritly

20. • -glycerols ; When entering tissue glycerols
change by enzymes to glycerol 3phosphate the
entering glycolytic pathway (glycolysis).
• -fatty acids; enter mitochondria only, in the
mitochondria degradation or break down of fatty
acids occur.
• it combine first with carrier substance
carnitine, the fatty acids split from carnitine to be
oxidize then enter Kerb's cycle for energy
production
Dr. Siham Gritly

21. • At rest, about 70% of the FFA released during
lipolysis are reattached to glycerol molecules to
form new triglycerides within the adipose tissues
• -During low-intensity exercise, this process is at
the same time as the overall rate of lipolysis
increases; as a result, the rate of appearance of
FFA in the plasma increases.
• Once they enter the plasma, the FFA molecules
are loosely bound to albumin, a plasma
protein, and transported in the circulation.
Dr. Siham Gritly

22. lipogenesis (building of lipids)
• *lipogenesis is the process of fat formation and
building up inside the body.
• *the liver is the main organ where lipids formed
as it contain enzymes that needed during
anabolism.
• *the liver enzymes resynthesize fatty acids and
glycerol again to triglycerides.
Dr. Siham Gritly

23. β oxidation of fatty acids
• *Beta oxidation is the process by which fatty acids, in
the form of Acyl-CoA molecules, are broken down in
mitochondria to generate Acetyl-CoA, then Acetyl-CoA
entre to the Krebs Cycle for production of energy.
All acetyl Co A formed in metabolism occurs in the
mitochondria
Formed from;
1-pyruvate oxidation
2-oxidation of fatty acids (β oxidation of fatty acid)
3-degradation of carbon skeletons of some amino acid
Dr. Siham Gritly

24. *-Free fatty acids can enter into the plasma membrane due
to their poor water solubility and high fat solubility.
Once in the cytosol of the cell, a fatty acid reacts with
ATP to give a fatty acyl adenylate, plus inorganic
pyrophosphate.
*-This reactive acyl adenylate then reacts with free Co-
enzyme A to give a fatty acyl-CoA ester plus AMP
*-The fatty acyl-CoA is then reacted with carnitine to
form acyl-carnitine, which is transported across the
inner mitochondrial membrane by a translocase enzyme
in the membrane.
Dr. Siham Gritly

25. Steps of beta oxidation of fatty acids in
mitochondria
1-in mitochondria; by series of chemical
reaction, fatty acid combined with acetyl Co A
and then converted to fatty acyl Co A, (loss of
carbon) this step need ATP.
2- fatty acyl Co A losses 2 hydrogen atoms
leaving double bond. the hydrogen atoms
combine with flavoprotein (FAD) to be
oxidized later.
Dr. Siham Gritly

26. 3-water (H2O) react at all site of double bond
4-2hydrogen atoms are removed, leaving double
bond. hydrogen combine with NAD
(nicotinmide adenine dinucleotide).
5-the split of fatty acid between the α and β
carbon produce long and short chain of fatty
acid
Dr. Siham Gritly

27. 6-short chain combine with original Acetyl Co A and enter
Kerb's cycle for more energy extraction.
this process is repeated until all fatty acids is split into
acyl C0 enzyme A.
Co-A enter Citric acid cycle combine first with
oxaloacetate to form citric acid and later degradation to
carbon dioxide and hydrogen atoms.
Co-A +oxaloacetate---citric acid
final breakdown of FA is the same as that of acetyl Co-A
formed from pyruvic acid during glucose oxidation
Dr. Siham Gritly

28. steps of the formation of Acetyl CoA (β oxidation of fatty acids
1- Dehydrogenation by FAD: The first step is the oxidation of the
fatty acid by Acyl-CoA-dehydrogenase. The enzyme catalyzes
the formation of a double bond between the C-2 and C-3. enzyme
acylCoA dehydrogenase.
End product trans-2-enoyl-CoA
Dr. Siham Gritly

29. 2- Hydration: The next step is the hydration of the bond
between C-2 and C-3.
Enzyme enoyl CoA hydratase
End product L-β-hydroxy-acyl CoA
Dr. Siham Gritly

30. 3- Oxidation by NAD+: The third step is the oxidation
of L-β-hydroxyacyl CoA by NAD+. This converts the
hydroxyl group (COOH) into a keto group (CH3-
CO-CH3). Enzyme hydroxy-acyl CoA dehydrogenase,
end product β-ketoacyl CoA
Dr. Siham Gritly

31. 4-thiolysis-: The final step is the cleavage of β-
ketoacyl CoA by the thiol (ketone) group of
another molecule of Co A. Enzyme β-
Ketothiolase. end product An acetyl CoA
molecule, and an acyl CoA molecule,.
Dr. Siham Gritly

32. Integration of metabolic pathways
Fatty acid oxidation occurs in the mitochondria , feeds acetyl
CoA into citric acid cycle and NADH/FADH2 into the electron
transport chain.
Dr. Siham Gritly

33. Formation of Ketone bodies
Ketone bodies are names given to acetoacetate, β-
hydroxybutyrate and acetone.
Serve as source of energy or fuel to peripheral
tissues. It is the overflow pathway for acetyl CoA
Acetoacetate and β-hydroxybutyrate are transported
by the blood to peripheral tissues, where they can
converted back to acetyl CoA and oxidized
through TCA cycle.
Dr. Siham Gritly

34. • Normally the concentration of ketone bodies in
the blood is very low,
• some times ketone bodies reach high level
when fatty acid oxidation increase
• Increase in ketone body formation result in a
condition known as ketosis
Dr. Siham Gritly

35. • *if the concentration of acetoacetic acid and β
hydroxybutyric rises to as high as 30 mg % above
the normal (3mg %), thus leading to extreme
acidosis.
• *acidosis is a condition where the pH of the blood
is below normal (pH 7.35). pH is a value
expressing the concentration of hydrogen ions in
the blood, the accumulation of ketone bodies can
disturb the body' acid-base.
Dr. Siham Gritly

36. • When carbohydrate intake is low, oxidation of
fatty acids accelerate to provide energy
through the production of acetyl CoA (TCA
substrate)
Dr. Siham Gritly

37. references
• Sareen Gropper, Jack Smith and James Groff, Advanced Nutrition and
Human Metabolism, fifth ed. WADSWORTH
• Melvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th
ed, McGraw Hill
•
• Heymsfield, SB.; Baumgartner N.; Richard and Sheau-Fang P. 1999.
Modern Nutrition in Health and Disease; Shils E Maurice, Olson A.
James, Shike Moshe and Ross A. Catharine eds. 9th edition
• Ellie Whitney and Sharon Rady Rolfes; Under standing Nutrition, Twelfth
Edition. 2011, 2008 Wadsworth, Cengage Learning
• Guyton, C. Arthur. 1985. Textbook of Medical Physiology. 6th
edition, W.B. Company
Dr. Siham Gritly

38. Saturated fat
Dr. Siham Gritly

39. Mono-saturated fat
Dr. Siham Gritly

40. Polyunsaturated
Dr. Siham Gritly

41. Saturated and trans fatty acids have
Dr. Siham Gritly

42. Trans and cis fatty acid
Dr. Siham Gritly

43. Lipoproteins found in the blood
Dr. Siham Gritly