How Fat Loss Works - Episode 4: Lipolysis and Beta-Oxidation (Getting Science as F***)
Summary
TLDRThis episode delves into the biochemical processes of fat metabolism, focusing on lipolysis and beta-oxidation. It explains how hormones trigger lipolysis to release free fatty acids from adipose tissue into the bloodstream. These fatty acids are then transported to tissues like the liver and muscles, where they undergo beta-oxidation, breaking down into acetyl CoA units. These units enter the Krebs cycle and oxidative phosphorylation, producing ATP, the body's energy currency. The video also touches on adaptive thermogenesis and the role of uncoupling proteins in regulating metabolic rate, offering insights into how the body manages energy production and expenditure.
Takeaways
- 🔬 The process of fat loss begins with lipolysis, where hormones and specific lipases hydrolyze stored triacylglycerols into free fatty acids.
- 🚀 Free fatty acids are transported in the bloodstream, either repackaged into triacylglycerides or bound to albumin, a type of protein.
- 🏋️♂️ The primary tissues that utilize free fatty acids are the liver and muscle, where they are released from albumin for further processing.
- 🔄 Beta-oxidation is the process where fatty acids are broken down into acetyl CoA units, which can then enter the Krebs cycle for energy production.
- ⚡ The initial step of beta-oxidation requires ATP, but it generates more ATP than it consumes, making it an energy-efficient process.
- 🚫 Contrary to popular belief, supplemental carnitine does not enhance fat oxidation as it is not the rate-limiting step in this process.
- 🛑 Carnitine's role is to transport fatty acids into the mitochondria, where beta-oxidation occurs, but it is not a limiting factor for fat loss.
- 🔋 ATP, or adenosine triphosphate, is the energy currency of the cell, and its production through oxidative phosphorylation is a key outcome of fat metabolism.
- 🔄 The Krebs cycle and oxidative phosphorylation are后续 steps in energy production from fatty acids, generating ATP, NADH, and FADH2.
- ♻️ Adaptive thermogenesis is a metabolic response that can increase or decrease the efficiency of ATP production, affecting the body's energy expenditure and fat loss potential.
Q & A
What is the first step in the process of burning stored fat?
-The first step in burning stored fat is lipolysis, which is controlled by hormones and specific lipases that hydrolyze triacylglycerols to form free fatty acids.
How are free fatty acids transported in the bloodstream?
-Free fatty acids are transported in the bloodstream either repackaged into triacylglycerols or bound to albumin, a type of protein.
What are the two main tissues that free fatty acids are transported to?
-The two main tissues that free fatty acids are transported to are the liver and muscle.
What is the role of carnitine in fat metabolism?
-Carnitine helps transport fatty acids into the mitochondria by binding to them, allowing them to cross the mitochondrial membrane through a protein called carnitine palmitoyltransferase.
Why does supplemental carnitine not provide additional fat loss benefits?
-Supplemental carnitine does not provide additional fat loss benefits because it is not the rate-limiting step of fat oxidation, and the carnitine in the body is recycled, making additional carnitine supplementation unnecessary.
What is the significance of beta oxidation in fat metabolism?
-Beta oxidation is significant because it is a process that cleaves fatty acids into two-carbon units, producing acetyl CoA units that can enter the Krebs cycle and eventually lead to ATP production.
How does oxidative phosphorylation contribute to energy production in the body?
-Oxidative phosphorylation contributes to energy production by using a hydrogen ion gradient to drive the synthesis of ATP from ADP and inorganic phosphate.
What are the byproducts of fat metabolism?
-The byproducts of fat metabolism are carbon dioxide, water, and ATP, with ATP being the body's energy source.
What is adaptive thermogenesis and how does it affect metabolism?
-Adaptive thermogenesis is a mechanism by which the body controls the rate of metabolism. It involves the production of uncoupling proteins that make the mitochondrial membrane 'leaky', reducing the efficiency of ATP synthesis and thus increasing the rate of metabolism.
Why does the body's metabolism slow down during long-term dieting?
-During long-term dieting, the body's metabolism slows down as a response to reduced energy intake. This is partly due to a reduction in the production of uncoupling proteins, which makes ATP synthesis more efficient, thus conserving energy.
How does the body regulate the transport of fatty acids into the mitochondria?
-The body regulates the transport of fatty acids into the mitochondria through the action of carnitine palmitoyltransferase, which facilitates the passage of fatty acids bound to acetyl CoA across the mitochondrial membrane.
Outlines
🔍 Understanding Fat Metabolism
This paragraph delves into the mechanisms of fat loss, starting with the process of lipolysis, where hormones and lipase enzymes break down stored triacylglycerols into free fatty acids. These acids are then transported in the bloodstream, either repackaged or bound to albumin, a protein that facilitates their movement to tissues like the liver and muscles. The focus is on the biochemical journey of fatty acids from storage to potential energy production, setting the stage for further discussion on fat oxidation.
🚀 Beta-Oxidation and Energy Production
The second paragraph explains beta-oxidation, the process where fatty acids are broken down in cells to produce energy. It details how fatty acids are activated by attaching them to acetyl CoA, an ATP-dependent reaction that requires energy but is essential for initiating the breakdown. The paragraph further discusses the transportation of these activated fatty acids into the mitochondria via carnitine, a molecule that facilitates their entry. Despite popular belief, supplemental carnitine does not enhance fat oxidation as it is not the limiting factor in this process. The summary emphasizes the role of beta-oxidation in energy production and the misconceptions surrounding carnitine's impact on fat loss.
🌡️ Adaptive Thermogenesis and Metabolic Efficiency
The final paragraph explores adaptive thermogenesis, a regulatory mechanism that influences metabolic rate. It discusses how the body's efficiency in energy production can vary, with overfeeding leading to increased production of uncoupling proteins that make energy production less efficient, thus promoting higher metabolic rates. Conversely, long-term dieting reduces these proteins, making ATP synthesis more efficient and potentially slowing metabolism. The paragraph concludes with a teaser for upcoming episodes that will offer practical advice on how this biochemical knowledge can inform dietary choices and lifestyle habits for effective fat loss.
Mindmap
Keywords
💡Lipolysis
💡Triacylglycerols
💡Free Fatty Acids
💡Beta-oxidation
💡Acetyl-CoA
💡ATP
💡Carnitine
💡Mitochondria
💡Krebs Cycle
💡Oxidative Phosphorylation
💡Adaptive Thermogenesis
Highlights
Introduction to the process of fat loss and beta-oxidation.
Explanation of lipolysis, the first step in burning stored fat.
Role of hormones and specific lipase in the activation of lipolysis.
Conversion of triacylglycerols into free fatty acids through lipolysis.
Transport of free fatty acids into the bloodstream and their repackage or binding to albumin.
Importance of liver and muscle tissues in the utilization of free fatty acids.
Beta-oxidation as the process of breaking down fatty acid chains.
Attachment of acetyl CoA to fatty acids and its ATP-dependence.
The energy yield from fats and its relation to ATP production.
The cost of ATP in the initial stages of beta-oxidation and its benefits.
Transport of fatty acids into the mitochondria via carnitine.
Clarification on the role of carnitine supplements in fat oxidation.
Beta-oxidation as a four-step process cleaving at the beta carbon.
Production of acetyl CoA units as a result of beta-oxidation.
The Krebs cycle's role in ATP production from acetyl CoA units.
Oxidative phosphorylation as the final step in ATP production.
ATP synthase and the creation of a hydrogen ion gradient for ATP regeneration.
Adaptive thermogenesis and its impact on metabolism and energy production.
The role of uncoupling proteins in the efficiency of ATP synthesis.
Practical recommendations on how fat metabolism affects diet and lifestyle.
Transcripts
[Music]
hey guys welcome back to my how fat loss
work series and today we have episode
for my pollicis and beta-oxidation
alright so we have talked about kind of
how fat moves in the body how its
transported how its digested how its
assimilated now we're going to talk
about how do you actually burn fat okay
now if we have fat stored as
triacylglycerols in the adipose tissue
the first step to getting them burned is
a process called lipolysis and this is
controlled by hormones specific lipase
okay and this lipase basically when it's
activated is going to hydrolyze
these triacylglycerols and that is going
to form free fatty acids that can then
move across the adipose cell wall okay
and out of the tissue right into the
bloodstream where the free fatty acids
can either be repackaged into tri so
glycerides or free fatty acids bound to
albumin okay albumin is a type of
protein and then it can be transported
to different tissues you know heart
intestine a lot of different things but
two of the main ones are liver and
muscle and once they get into these
tissues once again they have to be
released from albumin once they get into
these tissues unless you stay for muscle
for instance but this happens in liver
too now we have our free fatty acid
chain okay so this is the chain of fat
molecules and this is these kinks are
the hydrogen bonds alright with a
carboxyl group on the end now now we're
going to start going through a process
that's called beta oxidation and the
first step of this process is to attach
an acetyl co a on on to the fatty acid
group and this is an atp-dependent
próxima process ATP is your energy
currency of yourself okay
that's how your cell drives a lot of
unfavorable reactions so in order to
produce energy when we talk about
producing energy we talk about something
yielding energy like protein carbs and
fats we're talking about the ATP yield
okay so the more ATP we can produce from
fats the more energy we will have now
keep in mind more energy sounds great
but the more calories we consume the
more we're storing okay so the more ATP
we burn through the more fat we can burn
because they're gonna it's gonna require
okay so if we're doing a lot of exercise
or a lot of activity or if we have a
fast metabolism we're burning through a
lot of ATP and that's gonna cause
increase increase fat burning because we
have to make more ATP but this beginning
process actually costs us an ATP
molecule but that's okay because we're
going to make a lot more energy out of
it than we have to put into it so it
hydrolyzes an ATP into an A MP plus two
phosphate molecules that's not really
important but I'm gonna explain what
that means
so basically ATP stands for adenosine
triphosphate okay so it has three
phosphates on it and these are
high-energy phosphates and when you get
rid of one it causes it causes a release
of energy and this drives these
reactions okay in this case where I
should get rid of two phosphates which
is highly favorable and drives this
reaction once we take it through this
process we will now have a fatty acid
bound to koay okay now we're in the
cytoplasm of the cell we need to get
into the montec Andreea to actually burn
this fat this is where beta oxidation
takes place which is inside the
mitochondria but you can't just cross
the mitochondria these acetyl co a fatty
acids cannot just cross the
mitochondrial membrane they have to be
transported and the way they're
transported is they're bound to
carnitine okay you may have heard
carnitine from
there's a fat loss supplement people
have postulated that if we have more
carnitine we can transport more fatty
acids into the buttock Andreea membrane
inside the mitochondrial membrane and
burn them but that's not true
carnitine is not the rate limiting step
of fat oxidation so supplemental
carnitine does not seem to add
additional fat loss benefits but it's
bound to carnitine and this allows it to
go through a protein in the
mitochondrial membrane called carnitine
asil translocase okay so carnitine is
still translocase is transporting this
fatty acid bound to acetyl co a into the
mitochondria once it's inside the
mitochondria carnitine and the fatty
acid bound to co a break apart and the
carnitine can go back outside this
outside the mitochondrial membrane and
be used for transport again okay so that
carnitine gets recycled another reason
that adding additional carnitine really
isn't going to speed up this process now
you have your fatty acid bound to acetyl
co a inside the mitochondria now it's
going to go through a process called
beta oxidation that we've been talking
about now the reason that's called beta
oxidation is because it's going to
perform hydrolysis it's actually a four
step process and it's going to cleave at
the second carbon okay that's why it's
called beta oxidation it's cleaving at
the beta carbon okay so one two and it's
gonna lop it off it's gonna break it
apart in two carbon units okay
and each time it breaks it apart it's
gonna bring another KO a molecule so
that what you get is units of acetyl co
a as the product all right so these are
Co Co a units can then go through the
Krebs cycle then go through the Krebs
cycle and then to oxidative
phosphorylation
okay now the Krebs cycle you're going to
get ATP from because it produces FA VH
and NADH but I think it's important to
point out what action
the oxidative phosphorylation is
oxidative phosphorylation is how we get
energy it's how we make ATP and I'm
gonna summarize it for you here just so
you guys have an idea this is after
we've already gone through the krebs
cycle now I'm not going to go really
into the krebs cycle too much because it
will require more biochemistry than most
my audience has probably had access to
but essentially it is a cycle because it
regenerates and acetyl co a is the entry
product okay now once you've gone
through the Krebs cycle to produce ATP
you have this thing called ATP synthase
and it's embedded in the mitochondrial
membrane okay the way ATP synthase works
is you create a hydrogen ion gradient
okay so you've got ATP synthase and
you've got all these ADP's okay you've
got all these guys outside the
mitochondria and they've been used in
cellular reactions or whatever this is
the product typically of ATP hydrolysis
an ATP when it's used in a reaction ends
up as ADP plus P I now sometimes it's
converted to a MP and two phosphates
alright but usually it's converted to
ADP ADP stands for adenosine diphosphate
meaning one phosphate is cleaved off the
ATP molecule to drive whatever reaction
and you're left with ADP plus a
phosphate we need to regenerate ATP we
need to make more ATP ATP is the energy
currency of our cell okay
how do we do this we've got this ATP
synthase and remember this reaction to
create ATP is going to be highly
unfavorable that's gonna be very it's
very difficult requires a lot of energy
so how can we make this happen how can
we would generate this ATP well we do
what we what we have is these hydrogen
ion pumps okay
and they are gonna create what's called
a hydrogen ion gradient these are
hydrogen ions okay it's gonna pump them
out and so what we're gonna do is we're
gonna actually put way more hydrogen's
outside and there are inside what this
is called
coupling reactions okay so we're gonna
couple something that's favorable to
something that's unfavorable right so
when you let these hydrogen ions back in
the cell drive them back in the cell
you're able to also create ATP all right
and you are you've got other byproducts
your other byproducts are actually co2
in water so actually people asked like
how does like fat and carbohydrate and
stuff end up in your body you actually
pee it out and you breathe it out now
don't get any ideas of hyperventilating
it doesn't work that way okay but these
are the in products of metabolism is
carbon carbon dioxide water and ATP and
ATP is your body's energy source right
now one thing to point out is in
metabolism we have something called
adaptive thermogenesis okay
so adaptive thermogenesis you may have
heard of this it's kind of one of the
ways the body controls the rate of
metabolism okay when you're
metabolism is running fast you're
burning through a lot of calories you're
expending a lot of energy you are
actually part of that reason that's
running fast is because energy
production of it's in and of itself
becomes more wasteful okay see if we
bring back up our ATP synthase with this
hydrogen ion gradient remember we have
to create this to drive this reaction if
we're dealing with somebody who's highly
thermogenic they have high amounts of
water called uncoupling proteins and
these uncoupling proteins like UCP they
create what's called a leaky membrane
okay and that allows some of these
hydrogen ions to leak back into the cell
or sorry leak back into the mitochondria
what does that mean well since we have
less of a gradient now we're not able to
drive as much ATP synthesis and we're
actually getting less ATP per amount of
food that we eat okay so this is one of
the ways that your metabolism can speed
up when you're especially when you're
overfeeding your metabolism speeds up
you produce more uncoupling proteins
energy production becomes more
inefficient especially when left in time
when your metabolism is slowing down
when you've had when you've been dieting
for a long time you've had a reduction
in metabolic rate a lot of the way the
body adapts is by reducing the
production of these uncoupling proteins
so when you've been dieting for a long
period of time the uncoupling proteins
there's less of them be able to maintain
your gradient better and you're able to
produce more ATP per amount of food you
eat per calories you ingest so in this
way ATP synthesis becomes more efficient
which actually remember efficiency for
fat loss is a bad thing you want to be
really inefficient and energy production
because that means you have to eat more
food to get the same amount of energy
out of it okay so that's kind of a brief
rundown on how fat metabolism works and
how fatty acids are transported and then
oxidized and then go through oxidative
phosphorylation we got more episodes
coming up the next ones we're going to
make more practical recommendations on
how this actually affects things and how
different diets affect these things hope
you guys are enjoying this series and
I'll catch you next time remember to
like and subscribe to my channel leave a
comment and if you have any questions
you can email me at Lane at bio lang
comm thanks guys
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