Dietary Fat And Exercise Flashcards
How fats act in body (energy)
Glycogen sparing/training effect
Fatigue reduction
Energy dense (9kcal/g)
Low TEF (low energy cost for digestion/storage)
How fats act in body
Efficient storage (stored with little water)
Slow gastric emptying
Increased satiety
Food enjoyment
Fat soluble vitamins
Essential fatty acids (EFA)
What vitamins need fat to be absorbed
A,D,E,K
What are fats we need to eat that body doesn’t make
Essential fatty acids
What is fat primary fuel for
Light-mod exercise
How many total body calories in adipose tissue triglycerides
80,000
How many total body calories in muscle triglycerides
2,500
Lipids
Dietary fat, insoluble to water
- carbon, hydrogen, and oxygen
Triglycerides makeup
Glycerol backbone
3 fatty acids attached to each glycerol
What is broken down on triglycerides
Fatty acids broken down for energy
3 types of lipids
Triglycerides
Phospholipids
Cholesterol
Fat products
Animal products (fish very fatty), avocado, nut, seeds, whole grain, salad dressing, butter, mayo
ADMR for fat
19+: 20-35%
What is there none of for fat
RDA, AI, or UL, except for infants
What is there none of for fat
RDA, AI, or UL
What do dietary fats have
Different lengths and degrees of saturation
What is EAR for
Population (50 yr olds in America)
What is RDA for
One specific 50 yr old man
Where do we want most fats to come from
Unsaturated FAs
Breakdown for recommended intake
Saturated FAs 10%
- minimize trans fat
- max 7-10% from saturated and trans
Monounsaturated FAs 10%
Polyunsaturated FAs 10% (linoleic acid and a-linolenic acid)
Consuming <20% fat
Does not benefit performance
What is not recommended for performance based training sessions or competitions
High fat or low fat diets
Factors to consider for fat intake for athletes
- type of sport- training demands, energy systems used
- overall health
- performance
- body composition goals/ weight class
- time of competitive session/periodized nutrition
- training volume
Esterification (fat formation)
Formation of TG
- combination of an acid and alcohol (glycerol)= ester
When is the process of fat formation favoured
After eating a meal
- when body receives fatty acids and glucose
Fat lipolysis (TG lipolysis or hydrolysis)
Breakdown of TGs to yield energy (ATP) from FAs and glycerol
What happens to glycerol when broken down from TGs
To liver to make glucose
Breakdown (hydrolysis) favoured during
- exercise
- low calorie dieting/low energy availability
- fasting or starvation
- decreased insulin concentrations (CHO not present)
- increased growth hormone, cortisol and catecholamines (fight or flight)
- when body is cold
Lipolysis involves
3 hydrolysis reactions
What are the 3 hydrolysis reactions catalyze by
Hormone-sensitive lipase (HSL)
- Enzyme (breaking down)
2 major fates of fat after lipolysis
- re-esterification to TG (storage of fat)
- exit from fat cell (free FA, or attach to albumin)
Beta oxidation
Metabolism of fatty acids into acetyl CoA
How is acetyl CoA processed
Via Krebs cycle and electron transport system to produce ATP
At rest how much energy supplied by metabolism of fats
Nearly 60% (when consuming mixed diet)
At rest what is happening to FFAs?
Constantly being mobilized from adipose tissue to replenish plasma FFA
How many FFA released get re-esterfied back into TGs
70% and remainder delivered to body cells for energy
What are 2 major sources of ATP for exercise
CHO and fat
What kind of fat is metabolized during exercise
Free fatty acids - mainly long chain fatty acids (LCFA)
In muscle what are FAs used for
Energy or combined with glycerol (by-product of glycolysis)= storage as muscle TGs
What are the FAs used by muscle during exercise derived from
Plasma triglycerides
Plasma FFA
Fatty acids from IMTG (intramuscular TGs)
What is supply of plasma FFAs and what are they supplied by
Plasma FFAs are in very short supply and must be supplied by adipose TG stores
What catabolizes TG to glycerol and FFA
Hormone sensitive lipase (HSL)
What reduces hormone sensitive lipase activity
Consuming CHO during exercise
What can increase fat oxidation
Exercise (aerobic training)
- amount of increase is dependent upon intensity, duration of activity, dietary state and physical conditioning (training status)
Crossover concept
Point of exercise intensity at which body starts to rely more on CHO than fat as dominant fuel
What happens for crossover concept to occur
Lipolysis of TGs to FFA in adipose transport to blood, oxidizing in muscle mitochondria is too slow to keep pace with metabolic demand
Higher intensity exercise=
Lower fat usage
When is the release of FFA decreased from adipose tissue
At higher intensities of exercise
Why is release of FFA decreased from adipose at higher intensities of exercise
Reduced adipose tissue blood flow = decreased delivery of FFA to contracting muscle tissue
What are FFA levels seen at moderate exercise intensities
- additional FFA is provided during exercise at ~80% VO2max
What happens when additional FFA was provided at ~80% VO2max
FFA oxidation was increased but not fully restored
What limits FA oxidation at high intensities
Must be mechanisms within the muscle
During exercise how much FFA will go through re-esterification
Only 25%
- increase in FFA delivery to muscle cells
What does epinephrine secreted during exercise do
Stimulates breakdown of adipose TG and release of FFA into blood for transport to muscle for oxidation
How does epinephrine (during exercise) stimulate increase breakdown of TG and release FFA into blood for transport to muscle for oxidation
- muscle contraction activates transporters this increasing FFA uptake into muscle cell
- intramuscular lipases stimulated to catabolize muscle TG to FFA
- These FFA can enter mitochondria and be degraded to acetyl-CoA
At exercise intensities <25% VO2max how much fat is supplied for energy
80%
As exercise intensity increase >65% VO2 max what dominated supply of energy
CHO
What does CHO availability before exercise that increases blood glucose and insulin do to fat
Decreases the rate of fat breakdown and lipolysis
Gender differences for fat oxidation
Researchers have noted females may oxidize more fat during exercise at 65-75% VO2max
As exercise intensity/duration increases (>90mins) what happens to muscle glycogen
Stores decrease
As a result of msucle glycogen stores decreasing as exercise intensity/duration increases what happens to fat
Body switches to fat oxidation (use of FFA)
=only with a decreased intensity of exercise
How much energy does FFA produce during latter stages of extended exercise (i.e., ultramarathons)
FFA may produced ~90% of energy in extended exercise at lower intensities
Who oxidizes more fat
Trained individuals more vs sedentary individuals
Why do trained individuals oxidize more fat
Better at mobilizing, transporting, and oxidizing
What does training improve in relation to oxidizing fat
- blood flow to muscle-> more FFA
- Intramuscular triglycerides -> increased content and use
- sensitivity to epinephrine -> more FFA
- Increase in number and size of mitochondria
- FFA transport across mitochondrial membrane
- oxidative enzyme activity
What do trained athletes have a unique ability to do
Oxidize triglycerides when exercise intensity increases
What does oxidizing triglycerides when exercise intensity increases allow for
- more fat to be used as energy during exercise (glycogen sparing)
- doesnt alter total amount of energy expended, but proportion derived from CHO and fat
What do we want a mix of so pace is not affected
Fatty acids and glycogen
What is critical for endurance athletes
To become efficient ‘fat burners’
What does chronic high fat diet do
When adapt to low CHO or high fat diet you can increase the oxidation of fats
What do high fat diets decrease reliance on
Reliance on CHO as an energy source= potential of sparing muscle/liver glycogen
What do high fat diets do for exercise performance
No benefit with trained participants
What is goal of servings for fatty fish in week
2 servings (2 1/2 oz=1 serving)
How much added unsaturated fats in daily diet
2-3 Tbsp
What fats should be limited
Saturated, trans and animal fats
When should we try and limit fat intake
Leading up and during the competitive season
Why would we encourage an athlete involved in high intensity intermittent sport to limit fat intake pre competition
Might feel sick
Slow digestion
No performance advantage
CHO and fluid will have performance improvements
What do fish contain
An esssential fat
Omega 3 fatty acids
What do good fats do in our body
- direct blood vessels to dilate
- encourage blood to stay fluid (prevent clots, more flexible)
- reduce inflammation response seen in heart disease
- become part of our cell structure making them healthier
3 types of omega 3 fatty acids (an essential fat)
ALA- alpha-linolenic acid
EPA- eicosapentaenoic acid
DHA- docosahexaenoic acid
Benefits of EPA and DHA
Help with brain and eye development and may prevent cardiovascular disease
ALA food sources
Canola, soybeans, walnuts, flaxseeds
EPA and DHA food sources
Oily fish (herring, mackerel, salmon, sardines)
Other omega fatty acids essential to human health
Omega-6 and omega-9
Omega-6 food sources
Meats, poultry, eggs, nuts/seeds, plant based oils (canola, sunflower)
Types of omega 6
Linoleic acid and arachidonic acid
Concerns with omega 6
Excessive amounts in diet can contribute to inflammation and result in heart disease, cancer, asthma, arthritis, etc
What is goal for omega 3 and 6 intake
Balance between 6 and 3 dietary intake (2 or 4:1 ration)
Type of omega-9
Monounsaturated fats, oleic acids
Food sources of omega 9 fatty acids
Canola oil, sunflower oil, olive and nut oils, almonds
Do we have to eat omega-9
Can be produced by body but beneficial when consumed in diet
Benefits of omega 9 FAs
May help reduce risk of CVD and stroke, increase HDL and decrease LDL
What are canola and sunflower oil high and low in in
High in Monounsaturated fats
Low in saturated fats and free of trans fat
What dietary guidelines for fat should athletes follow
Same ones as general population
Training diet- focus on healthy fats/limited animal fats
When changes in body comp are required for performance or weight class
Reduce fat intake down to 20% total kcal
Keep protein up, drop CHO down
