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Week 6: Lipids (Fat Use During Physical Activity :check: (A balanced…

- - - - “Spot reducing” doesn’t work because muscles do not “own” the fat that surrounds them
  - - - TREND:Fat makes less and less of a contribution to the fuel mixture as intensity of activity increases
        
        Fat can only break down for energy by aerobic metabolism (need O2)
        
        Oxygen must be abundantly available for fat to fuel activity
        
        Therefore, if a person is breathing easily, muscle receives all the oxygen needed and are able to use more fat in the fuel mixture
    - - 3 types of adaptations
        
        Training stimulates the muscle cells to make more and larger mitochondria, the “powerhouse” structure of the cells that produce ATP for energy
        
        improves the heart and lung function and better able to deliver O2 to muscles at high activity intensities
        
        hormones slow down the glucose release from the liver and speed up the use of fat instead
- - - - Cell membrane:allows fat-soluble substances, including vitamins and hormones, to move in and out of the cells freely.
      - Emulsifiers
        
        in body:Allows fats to be suspended in the body and body fluids
        
        Important for fat to be digested and transported through the blood stream
        
        examples: Bile & lecithin
        
        in food: prevent the fat and water compounds in the food from separating
    - - Hydrophobic tails: 2 fatty acids tail
      - Hydrophilic head: Phosphate with nitrogen attached & Glycerol
  - - - Plant:Contains other types of sterols, stanols, and sitostanols
        
        Inhibits cholesterol absorption
      - Animal: Has cholesterol
        
        has 3 functions
        
        Structural component of cell membrane
        
        With phospholipids and proteins...
        
        Allows fat droplet to move freely through the water-based bloodstream
        
        creates the shell protecting chylomicrons
        
        Make three compounds: Bile acids, Vitamin D & Steroid hormones
        
        Harmful effect:accumulates in the artery wall and cause formation of plaques
        
        deposits lead to atherosclerosis
        
        Cause heart attacks and strokes
  - - - Glycerol
      - 3 Fatty Acids (same/different)
        
        (FA) Structure: Composed of a chain of carbon and hydrogen atoms, with an acid group (-COOH) at one end.
        
        4 ways to differentiate them
        
        The length of the carbon chain (4 - 24 C in the chain)
        
        [B] TREND: Longer carbon chain, higher melting point (THUS, fat is solid in rtp)
        
        3 types
        
        Medium: 6 to 12 C
        
        1 more item...
        
        Short: <6 C
        
        1 more item...
        
        Long: >12 C
        
        1 more item...
        
        The degree of unsaturation
        
        [B] TREND:The higher the saturation, the higher the melting point, hence more stable.
        
        3 types
        
        Monounsaturated:ONE double bond in the carbon chain is formed between 2 carbons by each giving up one hydrogen
        
        Polyunsaturated:At least 2 double bonds formed in its carbon chain
        
        Saturated
        
        3 more items...
        
        Location of Double Bonds
        
        in Polyunsaturated, as Essential Fatty Acids (EFA)
        
        Ω-3: (first double bond 3 carbons away from methyl end)
        :warning:
        
        Ω-6: (first double bond 6 carbons away from methyl end) :warning:
        
        In Monounsaturated
        
        Ω-9 : only C=C is nine carbons away from the methyl end
        
        Shape of the chain (straight or bent)
        
        2 types
        
        Trans fatty acids; Hydrogens attached to the C=C are on the opposite side
        
        1 more item...
        
        Cis fatty acids: Hydrogen attached to the double-bonded carbons are on the same side
        
        2 more items...
    - - with potentially HEALTHFUL lipids
        
        Omega-6 Polyunsaturated fats
        
        Non-hydrogenated margarine
        
        Monounsaturated Fats
        
        Avocado
        
        Peanut butter
        
        Omega-3 Polyunsaturated fats
        
        Fatty fish (eg Salmon)
        
        Walnuts
      - with potentially HARMFUL lipids
        
        Saturated fats
        
        Animal fats
        
        Trans-fats
        
        Partially/Fully Hydrogenated oils
        
        Shorterning
    - - Insulate and Protect the Body
        
        Subcutaneous fat (layer of fat just beneath the skin)
        
        provides insulation: Keeps body temperature at a constant level
        
        Visceral fat – packed around the organs
        
        Provides cushioning and prevent them from moving around and getting injured
      - Essential Fatty Acids (EFA) Functions
        
        Eicosanoids, made from essential fatty acids, involve in more than 100 actions
        
        Regulating blood pressure: influence blood vessels to constricts and raise BP)
        
        Blood clotting: some help to form blood clots while some prevent blood clots
        
        Inflammation or hypersensitivity reactions (e.g. asthma): some promotes while some prevent inflammation
        
        Immune and allergic response
        
        Omega-3 fatty acid docosahexaenoic acid (DHA)
        
        During first few weeks of embryonic life: important for normal development and maturity of the nervous system
        
        Fetal life and infancy: for normal development and function of the retina (a part of the eye that senses light)
        
        Throughout life: to regulate nerve transmission and communication
        
        EFA along with phospholipids & cholesterol: Keep cell membrane fluid and flexible, so that substances can flow into and out of the cell membrane
      - Provide Compact Energy Storage:
        Main storage form of energy
        
        Excess calories derive from carbohydrates, proteins, and alcohol can be converted into triglycerides
        
        Great storage area due to
        
        Stability and calorie dense
        
        Can expand 2-3 times their normal size (a single adipose fat cell can increase in weight about 50 times)
      - Aid Fat-Soluble Vitamin (eg Vitamin A) Absorption and Transport
        by dietary fats
        
        High risk of fat-soluble vitamins malabsorption in individuals who:
        
        Eat extremely low fat diet
        
        Diseases causing fat malabsorption
        
        Consume certain medications
      - Provide Rich source of Energy
        
        Primary fuel source for all body cells, except the nervous system and red blood cells
        
        Provides 30 – 70% of the energy expenditure when an individual is resting or engaging in a light physical activity
        
        Exact amount is dependent on
        
        The glycogen stores
        
        How physically fit
        
        Intensity and duration of the exercise
- - - - Breaks down some of the fats into a fatty acid and a diglyceride
        with lipase enzymes
      - Liver and Gallbladder
        
        liver produces bile, stored in the gallbladder and released through the bile duct into the small intestine (SI).
        
        Bile aids in fat digestion and absorption by emulsifying lipids in the digestive juices
        
        Pancreas
        
        Small intestine: Main site of digestion & absorption
        
        [refer to Introduction of lipids for absorption]
        
        Anus
        
        Emulsified fats (Triglycerides) ---> Monoglycerides, glycerol, fatty acids (absorbed)
        with Pancreatic (and intestinal) lipase
- - - - High PUFA intake
        (>10%)
        
        may increase the amount of cholesterol deposited in arteries
        
        Thus, increasing the risk of CVD
        
        May also impair the immune system’s ability to fight disease
      - Excessive Ω-3 FA intake
        
        impair the function of immune function, allow uncontrolled bleeding, cause haemorrgic stroke; usually due to supplementation
      - Intake of Rancid Fats
        
        Damage cells due to the presence of compounds (peroxide and aldehydes)
      - Diet high in Trans-fat
        
        Raises blood cholesterol levels, hence increasing the risk of heart disease
        Reduces HDL and promotes inflammation in the body
      - Imbalances of Ω-3 & Ω-6 FA
        
        Both FA compete with each other because both use the same metabolic pathways
        
        Low intake of Ω-3 FA may worsen inflammatory diseases,
        
        high intake of Ω-6 promotes inflammation
      - Diet high in Total Fat
        
        Increase the risk of obesity, certain types of cancer (e.g. colon, prostate, breast) and cardiovascular disease
        Increase blood cholesterol levels
    - - Weight control
      - Replace saturated fats with monounsaturated fat or polyunsaturated fats
      - Dietary fibers
      - Phytochemicals
      - Moderate alcohol consumption
      - Physical activity