fat

Question 1

What are fats also known as?

Answer 1

Lipids

Question 2

What does lipos mean?

Answer 2

Fat

Question 3

What two types are fats referred to?

Answer 3

Dietary fat (food and drink) and stored fat (in body)

Question 4

Are fats water-soluble?

Answer 4

Fats are hydrophobic (water-insoluble) but lipophilic (fat-soluble).

Question 5

Where are fats primarily digested?

Answer 5

In the stomach and duodenum.

Question 6

What are the three main classifications of fats?

Answer 6

1. Triglycerides
2. Phospholipids
3. Sterols

Question 7

What are triglycerides?

Answer 7

Triglycerides are the most abundant lipids and make up the majority of dietary fat

Question 8

What percentage of dietary fat is in the form of triglycerides (TAGs)?

Answer 8

Over 90% of dietary fat.

Question 9

What are the different forms of glycerides?

Answer 9

• Monoglycerides – one fatty acid + glycerol
• Diglycerides – two fatty acids + glycerol
• Triglycerides – three fatty acids + glycerol

Question 10

What are the primary functions of triglycerides?

Answer 10

• Protection and insulation (e.g., cushioning organs, thermal insulation).
• Energy source (primary fuel for low-intensity exercise and rest).
• Electrical insulation (protects nerve signals via the myelin sheath).
• Transport of fat-soluble vitamins and nutrients.
• Satiety and sensory qualities (flavour, texture, digestion time).

Question 11

How much energy does fat provide?

Answer 11

1 gram of fat = 9 kcal.

Question 12

What is the main form of fat stored as?

Answer 12

Triacylglycerol (TAG)

Question 13

Where is most fat stored in the body?

Answer 13

• Adipose tissue
• Liver
• Skeletal muscle (as triglycerides, but must be broken down into fatty acids and glycerol before use).

Question 14

How are fatty acids classified based on carbon chain length?

Answer 14

• Short-chain fatty acids: <6 carbons
• Medium-chain fatty acids: 6-12 carbons
• Long-chain fatty acids: >12 carbons

Question 15

What is the difference between saturated and unsaturated fats structure?

Answer 15

• Saturated fats have NO double bonds (solid at room temp, mainly from animal sources).
• Unsaturated fats have one or more double bonds (liquid at room temp, from plant sources).

Question 16

What are the two types of unsaturated fats?

Answer 16

• Monounsaturated fats (MUFA) – one double bond
• Polyunsaturated fats (PUFA) – more than one double bond

Question 17

What is the reaction that forms fat molecules?

Answer 17

Condensation reaction (removal of water when a bond is made).

Question 18

What determines an omega fatty acid’s classification?

Answer 18

The location of the first double bond from the omega end

Question 19

Where is the first double bond in omega-3, omega-6, and omega-9 fatty acids?

Answer 19

• Omega-3 – 3rd carbon
• Omega-6 – 6th carbon
• Omega-9 – 9th carbon

Question 20

What are the three forms of omega-3 fatty acids?

Answer 20

1. Alpha-linolenic acid (ALA) – from plant oils (flaxseeds, soybeans).
2. Eicosapentaenoic acid (EPA) – from fish oils.
3. Docosahexaenoic acid (DHA) – from fish oils.

Question 21

What are the benefits of omega-3 fatty acids?

Answer 21

They dilate blood vessels, reduce inflammation, and support heart health

Question 22

How do omega-6 fatty acids affect the body?

Answer 22

They promote vasoconstriction and inflammation.

Question 23

What is the typical omega-6 to omega-3 ratio in a Western diet?

Answer 23

16:1 (compared to an ideal 1:1).

Question 24

Why are trans fats harmful?

Answer 24

They are unnatural, hard to break down, and easily stored in the body (stack)

Question 25

What foods commonly contain trans fats?

Answer 25

Pastries, cakes, biscuits, donuts

Question 26

What is CIS bonding?

Answer 26

H on the same side as C chain - weakened interaction = bend

Question 27

What is Trans bonding?

Answer 27

H are opposite sides of C chain - stronger interaction = flat chain

Question 28

What percentage of total daily calories should come from fat?

Answer 28

20-35%.

Question 29

What is the recommended intake of different fats?

Answer 29

* Saturated fats: 7-10% of total calories * Monounsaturated fats: ~10% * Polyunsaturated fats: ~10%

Question 30

Why should fat intake not drop below 20% of total calories?

Answer 30

For health and proper body function

Question 31

What is the breakdown of lipids called?

Answer 31

Lipolysis and takes place in the adipose tissue and skeletal muscle

Question 32

What enzymes are involved in breaking down lipids in adipose tissue?

Answer 32

Adipose triglyceride lipase, Hormone sensitive lipase, Monoacylglycerol lipase

Question 33

What enzymes are involved in breaking down lipids in muscle?

Answer 33

Hormone sensitive lipase

Question 34

What are phospholipids composed of?

Answer 34

* Glycerol backbone * Two fatty acids * Phosphate group

Question 35

What is the role of phospholipids in digestion?

Answer 35

They act as emulsifiers, breaking fat into smaller droplets for digestion

Question 36

How do phospholipids behave in water?

Answer 36

They have hydrophilic heads (water-attracting) and hydrophobic tails (water-repelling).

Question 37

What is fatty acid saturation?

Answer 37

- Refers to the number of hydrogens on each carbon atom - A saturated fatty acid has the maximum number of hydrogen on each of its carbons (no double carbon bonds). Saturated with H - An unsaturated fatty acid has one or more double bonds between carbon molecules

Question 38

What are sterols, and how do they differ from other lipids?

Answer 38

Sterols have hydrocarbon rings instead of chains.

Question 39

What is the key example of a sterol?

Answer 39

Cholesterol

Question 40

What are the functions of cholesterol?

Answer 40

* Structural component of cell membranes. * Precursor for vitamin D, steroid hormones, and bile salts

Question 41

What are high-density lipoproteins (HDL)?

Answer 41

Good cholesterol" – removes excess cholesterol from the blood via liver

Question 42

What are low-density lipoproteins (LDL)?

Answer 42

Bad cholesterol" – delivers cholesterol to cells but can contribute to artery plaque build-up.

Question 43

What are ways to lower cholesterol levels?

Answer 43

* Limit saturated and trans fats. * Keep cholesterol intake <300mg/day. * Maintain an active lifestyle. * Eat more fruits and vegetables

Question 44

How are fatty acids converted into usable energy?

Answer 44

Through beta-oxidation, producing Acetyl CoA for ATP production.

Question 45

How are short and medium fatty acids absorbed?

Answer 45

They are water soluble so move via passive diffusion They go into the blood stream via capillaries Glycerol can also go into blood stream

Question 46

How are long chain fatty acids, monoglycerides, phospholipids, and cholesterol absorbed?

Answer 46

These form fat droplets, which are water-insoluble and cannot diffuse like short and medium-chain fatty acids. Bile salts surround the fat droplets to form micelles, which transport fats to the intestinal wall. Micelles are absorbed into microvilli, where their contents are converted back into triglycerides, phospholipids, and cholesterol. These are transported via the lymphatic system as lipoproteins. Some fats are used for immediate energy, while others go to the liver, muscles, or adipose tissue for storage and other functions.

Question 47

How are fats broken down for energy?

Answer 47

Lipolysis – fats are broken into glycerol and fatty acids for use in muscles.

Question 48

What is the difference in fuel sources for endurance vs. ultra-endurance events?

Answer 48

* Endurance events (e.g., marathons) rely more on carbohydrates and some fat. * Ultra-endurance events rely more on fat metabolism