232 Fat
What food sources contain phospholipids?
Natural EX's --> eggs, liver
Added as emulsifiers --> salad dressing
What are phospholipids composed of?
Fatty acids, phosphate, alcohol and glycerol
What is the function of phospholipids?
Allows absorption of substances across the cell membrane
--> phospholipid bilayer
Where are phospholipids abundant?
across all biological membranes in the body
What type of lipid is cholesterol?
a sterol
What food sources is cholesterol found in?
animal based foods such as eggs, meat, poultry, cheese and milk
Can cholesterol be synthesized in the body?
yes
What is VLDL and what does it do?
Very Low Density Lipoprotein: a package that carries cholesterol and triglycerides from the liver to the rest of the body's cells. Converted into LDL or Bad cholesterol
What is the function of HDL?
High Density Lipoprotein: Brings cholesterol back to the liver
--> good cholesterol
What is the function of Cholesterol?
A structural component of cell membranes;helps repair and form new cells; necessary for synthesizing steroid hormones e.g.,testosterone and bile
Does dietary cholesterol correlate to higher total blood cholesterol levels?
no, but be cautious if you have CVD or diabetes
What does a plant sterol do?
Similar in structure to cholesterol and therefore interferes with
the body’s absorption of cholesterol
What are examples of Omega 3 fats?
EPA, DHA, ALA
What is an example of an Omega 6 fat?
Linoleic Acid
How should polyunsaturated fats be consumed?
should be eaten in small amounts for optimal health
What are some functions of polyunsaturated fats?
Epithelial cell function (cells which line blood
vessels and organs)
Regulation of gene expression
Synthesis of eicosanoids (signaling molecules that
reduce pain and inflammation)
Where are saturated fats found?
Visible fat on meat, cheese,butter, full fat dairy and coconut oil
What is a function of saturated fats?
Structural component of cell membranes – less permeable
Can saturated fats be produced in the body?
yes, are not needed in diet
What are the 4 steps of fat digestion and absorption?
1. Mouth: Mechanical and chemical digestion (lingual lipase)
2. Partially broken-down droplets arrive at the small intestine.Bile and pancreatic lipase break the units into free fatty acids, glycerol, cholesterol and phospholipids for absorption
3. Breakdown products are repackaged as chylomicrons inside the small intestine and enter the blood stream
4. Fatty acids are delivered to fat cells for storage or muscle cells for energy
What is the importance of dietary fats?
1. Dense source of energy - 9 kcals/g
2. Provide essential fats
• Omega 3
• Omega 6
3. Rich source of VitaminsA,D,E,K
4. Makes food highly palatable!
What are 5 functions of bodyfat?
1. Insulate against heat loss
2. Keep skin and other tissues soft and pliable
3. Organ protection
4. Structural: cell membranes,steroid hormones e.g.testosterone
5. Nerve insulation (myelin) – transmission of nerve impulses
What % of total energy intake should consist of fat?
20-35% of total energy intake
--> or 2-3 tablespoons of healthy fat per day
What type of fats should we aim to eat more than others?
Mono/Polyunsaturated > saturated fat
What are some reccomendations to limit fat intake?
• Aim to steam,roast,boil or bake foods where possible to limit fat use
• Flavour food with garlic,lemon,vinegars,herbs and spices rather than extra fats
• Ask for dressings and sauces on the side of your dish when eating out
what are some reccomendations for increasing polyunsaturated fat intake?
Eat fish twice per week
Chia,flax,nuts,seeds on salads,cereal etc.1-2 tbsps.per day
Consider an EPA/ DHA supplement (FDA recommends not exceeding 2g/day DHA and EPAas supplements)
What oils should we use for what cooking purposes?
Olive oil: frying, sautéing,deep frying - your default oil
for pretty much anything
• Extra virgin olive oil; drizzle – dressings,salads,dips
• Bake with sunflower oil
• Use butter or coconut oil for medium heat cooking
(sauté and low heat roast)
• Avocado oil – super high heat cooking
How did reducing saturated fat affect CVD rates?
21% decrease in CVD including heart attacks and strokes
Who can benefit from decreasing saturated fats?
anyone --> seemingly healthy people and those at higher risk for CVD and those who have already had a heart attack and stroke
- they all benefitted the same
how does decreasing saturated fats protect against CVD?
decreasing saturated fats lead to serum total cholesterol
- therefore more protection
is there a link between dairy and CVD
one hasn't been found, fermented milk products might confer a benefit for CVD risk
What is ketosis?
a response in the liver to extremely low carb intake
uses alternative fuels for energy:
1. Acetoacetate
2. B-hydroxybutyrate
3. Acetone
> 1mm/L indicates ketosis
what is the body's response to ketosis?
INITIALLY:
• ↓ circulating glucose, subsequently insulin ↓
• ↑ in glucagon = ↑ Glycogenolysis, ↑ Gluconeogenesis,
↑ Lipolysis and β-oxidation
• Small number of ketone bodies
AFTER 2-3 DAYS:
• ↑ gluconeogenesis from protein breakdown and glycerol from lipolysis
• cannot continue breaking down muscle protein
How does the body adapt to a ketogenic diet after 3 weeks?
1. ↑ ketogenesis to provide fuel for brain
2. Lipolysis continues - producing glycerol + fatty acids
3. ↑ gluconeogenesis from glycerol
4. Thyroid hormone T3 falls = ↓ metabolic rate
5. ↓ rate of protein breakdown
How does keto affect sports performance?
Not used as a strategy to manipulate BW for competition
--> longer term approches are favoured
Weight loss strategies depend on the athlete, event and individual tolerance
Who is a ketogenic diet not advisable for?
• those under 18 without medical supervision
• Immunocompromised individuals
• Individuals with a history of an eating disorder
• People who have a history of poor discipline
• Athletes who are relying on high intensity for their sport