How Fat Loss Works - Episode 2: Fat Metabolism

Summary

This educational video delves into fat metabolism, explaining how fats are digested and transported in the body as chylomicrons through the lymphatic system into the bloodstream. It clarifies that fats, being hydrophobic, must be repackaged to traverse hydrophilic bodily fluids. The video distinguishes between fat metabolism during caloric surplus and deficit, emphasizing that while insulin affects fat storage, it isn't necessary for it. It also highlights the body's preference for fat as an energy source to spare glucose and muscle glycogen, especially during a caloric deficit, and discusses the impact of high-fat versus high-carb diets on fat oxidation and storage.

Takeaways

• 🔍 Fat metabolism is a complex process involving digestion, transportation, and storage of fatty acids in the body.
• 🌀 Fat digestion primarily occurs in the small intestine, specifically in the duodenum, and is different from carbohydrate and protein digestion.
• 🚛 Chylomicrons are large globules of fat that transport dietary fat through the lymphatic system into the bloodstream.
• 🧬 Fat is hydrophobic, meaning it does not mix with water, and thus must be packaged in chylomicrons to travel through the body's hydrophilic environment.
• 🔄 The process of fat entering and exiting cells involves being repackaged and unpackaged to cross cell membranes.
• ⚡ High rates of fat oxidation are associated with a caloric deficit, where the body burns more fat for energy.
• 🔄 In a caloric surplus, particularly with a high-fat diet, the body both burns and stores more fat, with the net balance determining fat loss or gain.
• 🍽 The type of diet (high carb vs. low carb, high fat vs. low fat) influences the rate of fat oxidation and the amount of fat stored.
• 🏋️‍♂️ During exercise, especially high-intensity activities, the body prefers to use glycogen over fat to spare energy for quick, intense bursts.
• 💊 The body does not require insulin to store fat as body fat, contrary to some common beliefs.
• 🔄 In a negative energy balance, the body liberates fatty acids from adipose tissue to meet energy demands, prioritizing blood glucose stability and sparing muscle glycogen.

Q & A

What is the main topic of the video script?

The main topic of the video script is fat metabolism, specifically discussing how fat moves and fluxes in the body depending on different states such as caloric surplus or deficit, and the role of insulin in fat storage.

How does fat digestion differ from carbohydrate and protein digestion?

Fat digestion is different because it mostly occurs in the small intestine, particularly in the duodenum, and involves packaging fat into chylomicrons, which are large globules of fat that pass through the lymphatic system before entering the bloodstream.

What are chylomicrons and what role do they play in fat metabolism?

Chylomicrons are large globules of fat that are formed during fat digestion. They play a role in transporting dietary fat from the digestive system into the bloodstream via the lymphatic system.

Why are fats considered nonpolar and how does this affect their interaction with water?

Fats are considered nonpolar due to their hydrophobic nature, meaning they do not mix well with water. This is because they tend to associate with other hydrophobic substances, leading to the formation of separate phases when mixed with water.

How does the body transport fat across different barriers within the body?

The body transports fat by packaging it into vehicles like chylomicrons and very-low-density lipoproteins (VLDLs) to move through hydrophilic mediums such as the bloodstream. Fat must be unpackaged to cross membranes and repackaged on the other side.

What is the storage form of fat in the body and how is it utilized?

The storage form of fat in the body is triacylglycerol, which is a glycerol molecule with three fatty acid chains. It is utilized by being broken down into individual fatty acids and glycerol, which can be used for energy or converted into glucose through gluconeogenesis.

Does insulin play a role in fat storage in the body?

Insulin is not required for fat storage in the body. The video script clarifies that a common misconception is that insulin is necessary for fat to be stored as body fat, but this is not the case.

How does a high-fat, low-carbohydrate diet affect fat metabolism?

A high-fat, low-carbohydrate diet leads to increased fat oxidation due to the higher availability of fat as a fuel source, but also results in increased fat storage because of the lack of insulin, which is a storage hormone.

What is the process called when the body converts carbohydrates into fat?

The process of converting carbohydrates into fat is called de novo lipogenesis, which primarily occurs in the liver and results in the production of very-low-density lipoproteins (VLDLs).

How does the body prioritize energy sources during a caloric deficit?

During a caloric deficit, the body prioritizes fat as an energy source to spare muscle glycogen and maintain blood glucose levels, leading to increased fat oxidation and potentially decreased fat storage depending on the diet's macronutrient composition.

What determines whether the body gains or loses fat according to the script?

According to the script, the net balance of energy intake versus energy expenditure determines whether the body gains or loses fat, regardless of the macronutrient composition of the diet.

Outlines

00:00

🔍 Understanding Fat Metabolism

The speaker begins by introducing the second part of a series on fat loss, focusing on fat metabolism. They briefly touch on fat digestion, which mainly occurs in the small intestine, specifically the duodenum. Fat, being nonpolar, is packaged into chylomicrons, large globules that travel through the lymphatic system before entering the bloodstream near the clavicle. The chylomicrons can then be delivered to various tissues, such as the liver and adipose tissue, where they can be repackaged into different lipoproteins or broken down for energy use. The speaker emphasizes the hydrophobic nature of fat and its need to be packaged for transport through hydrophilic mediums like blood and lymph.

05:01

🚀 Fat Digestion and Storage

This paragraph delves deeper into the digestion and storage of fat. The speaker explains that fat is stored in the body primarily as triacylglycerols, which are composed of a glycerol molecule and three fatty acids. When the body requires energy, these triacylglycerols are broken down into glycerol and fatty acids. The glycerol can be used for gluconeogenesis in the liver, while the fatty acids can cross cell membranes and be repackaged for transport to tissues where they can be used for energy. The speaker clarifies that fat does not require insulin for storage, contrary to common belief, and that the net balance of fat intake and expenditure determines fat loss or gain.

10:02

🍽️ Macronutrient Intake and Fat Metabolism

The speaker explores how different macronutrient intakes affect fat metabolism. They use examples of high-fat, low-carbohydrate meals versus high-carbohydrate, low-fat meals to illustrate the impact on fat oxidation and storage. In a caloric surplus with a high-fat diet, there is an increased rate of fat oxidation but also increased fat storage due to the high intake of fat. Conversely, in a caloric deficit with a high-carb diet, fat oxidation is lower, and less fat is stored because there is less fat intake. The speaker highlights that while insulin levels can influence the storage of fat, the overall energy balance is the key determinant of fat loss or gain.

15:05

🔄 Energy Balance and Fat Flux

The final paragraph addresses the concept of energy balance and its role in fat metabolism. The speaker explains that in a negative energy balance, the body will liberate fatty acids from adipose tissue to meet its energy needs, as it seeks to maintain blood glucose levels and spare muscle glycogen. This process is influenced by the type of diet, with high-fat diets leading to more fat oxidation and storage, and high-carb diets leading to more carbohydrate oxidation and less fat storage. The speaker concludes by emphasizing that the body's primary goal is to maintain energy balance, and that the actual amount of fat lost or gained is dictated by this balance, not solely by the diet's macronutrient composition.

Keywords

💡Fat Metabolism

Fat metabolism refers to the process by which the body breaks down fats into energy. In the context of the video, this is a central theme as it discusses how fats are digested, absorbed, and utilized by the body. The script explains that fats are metabolized differently than carbohydrates and proteins, with a focus on the role of chylomicrons in transporting dietary fats through the lymphatic system into the bloodstream.

💡Chylomicrons

Chylomicrons are large lipoprotein particles that transport dietary fats from the intestines to other tissues in the body. The video script describes chylomicrons as 'big globules of fat' that are formed during the digestion of fats and are crucial for fat transport in the body. They are broken down into individual fatty acids and glycerol, which can then be used for energy or repackaged for storage.

💡Hydrophilic and Hydrophobic

Hydrophilic refers to 'water-loving' substances that dissolve well in water, while hydrophobic means 'water-fearing' and describes substances that do not mix well with water. The video uses these terms to explain the behavior of fats (hydrophobic) and how they need to be packaged into chylomicrons to be transported through the hydrophilic bloodstream and other body fluids.

💡Lymphatic System

The lymphatic system is a network of vessels and organs that play a role in immune function and the transport of fats. The script mentions that chylomicrons, after being formed in the small intestine, enter the lymphatic system before being dumped into the bloodstream near the clavicle. This system is essential for the absorption and distribution of dietary fats.

💡Triacylglycerols

Triacylglycerols, also known as triglycerides, are the main form of stored fat in the body and the form in which most dietary fats are consumed. The video script explains that triacylglycerols consist of a glycerol molecule attached to three fatty acid chains. They are broken down into glycerol and fatty acids when the body needs to use fat for energy.

💡Fatty Acids

Fatty acids are the building blocks of fats and are released from triacylglycerols for energy production. The video discusses how fatty acids are broken down from triacylglycerols by lipases and then transported to various tissues, such as the liver and muscles, where they can be oxidized for energy or repackaged into other lipoproteins.

💡Insulin

Insulin is a hormone that regulates blood sugar levels and plays a role in fat storage. The script clarifies a common misconception that insulin is necessary for fat storage, stating that while insulin is a storage hormone, it is not required for the body to store fat. The presence of insulin influences the balance between fat oxidation and storage.

💡Caloric Surplus and Deficit

A caloric surplus occurs when energy intake exceeds energy expenditure, leading to weight gain, while a caloric deficit is the opposite, leading to weight loss. The video uses these concepts to explain how fat storage and oxidation rates are influenced by overall energy balance, regardless of the macronutrient composition of the diet.

💡De Novo Lipogenesis

De novo lipogenesis is the process by which the body converts excess carbohydrates into fat. The video script mentions this process as a way the body can store fat even from carbohydrate intake, although it notes that this is a minor pathway unless there is a very high carbohydrate intake and very low fat intake.

💡Energy Balance

Energy balance is the state where total energy intake equals total energy expenditure. The video emphasizes that energy balance is the primary determinant of whether the body gains or loses fat, more so than the specific macronutrient composition of the diet. It explains that even with different diets, the body's fat storage or loss is dictated by the net energy balance.

Highlights

Fat metabolism is a complex process involving digestion, transportation, and storage.

Fat digestion primarily occurs in the small intestine, particularly the duodenum.

Fats are packaged into chylomicrons, which are large globules that travel through the lymphatic system.

Chylomicrons eventually enter the bloodstream near the clavicle area.

Fats must be repackaged to move through hydrophilic mediums like blood.

Fats are broken down and repackaged in the liver into various lipoproteins.

Fats are also stored in adipose tissue and can be used by other tissues for energy.

Fat must be unpackaged to cross cell membranes and repackaged once inside.

Triglycerides are the storage form of fat and are composed of a glycerol molecule and three fatty acids.

Glycerol can be used for gluconeogenesis or repackaged into another triglyceride.

Fatty acids can be oxidized for energy or repackaged and stored.

Fat storage and oxidation rates depend on insulin levels and dietary macronutrient composition.

High-fat, low-carb diets can lead to increased fat storage despite higher fat oxidation rates.

Insulin is not necessary for fat storage, contrary to popular belief.

Low-fat, high-carb diets can result in less fat oxidation but also less fat storage.

De novo lipogenesis is a process where carbohydrates can be converted to fat, but it is not a major contributor to fat storage under normal conditions.

Energy balance, not insulin levels, ultimately determines whether fat is gained or lost.

In a negative energy balance, the body liberates fatty acids from storage to meet energy demands.

In a positive energy balance, fat is stored in adipose tissue due to excess caloric intake.

Transcripts

[Music]

hey guys welcome back to the second part

of my series about how fat loss works

part 2 is fat metabolism okay so I don't

want to go too much into digestion and

especially beta-oxidation today which

we'll talk about later but I do want to

talk about kind of overall how fat moves

and fluxes in the body depending on what

state you're in okay so fat digestion is

much different than carbohydrate and

protein a lot of it occurs in the small

intestine mostly in the duodenum and

they're actually packaged into these

these these kind of fat I want say

vehicles but they're called chylomicrons

and they're these big globules of fat

basically so fat is what we call

nonpolar so you ever say heard people

say oil and water don't mix right well

oil is fat and if you take oil put it

into water it will all it will start up

and maybe start out as different

droplets but it'll eventually all come

together right like you know it will

it's what's called hydrophobic and

hydrophobic things want to associate

with other hydrophobic things so what

you'll have is there's these big

globules what they're called

chylomicrons and they're just big

globules of fat and they go through your

what's your called your lymphatic system

and they actually end up dumping out

from digestion into the bloodstream

somewhere up around your clavicle area

so once they're in the bloodstream they

can then go to different tissues like

the liver where they can be repackaged

into like mmm they be broken down and

repackaged into like vldls LDLs hdls

some other things and they can also go

to adipose tissue and then go skeletal

muscle and then go to other tissues like

heart and

you know some any other tissue that the

burns fatty acids so similarly it now

keep in mind whenever you cross a

barrier with fat okay what happens is it

has to be packaged because the

bloodstream and all the other kind of

the fluid parts of your body are

hydrophilic so they're they're mostly

water so they have to be packaged into

something that can move through these

mediums all right and then to get across

the membrane they have to be unpackaged

taken through the medium and then

repackaged okay so in the case of kala

microns for example in the intestine the

fat you eat goes through your digestive

process and then it gets to the duodenum

you have pancreatic lipase --is that

then break down those most the fat sweet

our trial glycerides which we'll talk

about more in a minute so they they

break down these triglycerides they go

through the intestinal lumen they come

out in the lymphatic system or they go

through the intestinal lumen repackaged

and then go through the lymphatic system

into the bloodstream okay now these

chylomicrons when they get to let's say

adipose tissue they're then again broken

down by life phases okay into individual

fatty acids and then they are then they

can cross the membrane they can cross

the membrane of the adipose cell all

right they can go into that fat cell and

then they're repackaged again in to try

so glycerides okay so and that's going

to happen in the liver and muscle to

whenever they just come trying to ki let

you keep in mind whenever fat crosses a

barrier it has to be it whatever package

it's being delivered in it has to be

unwrapped and then once it's in the

inside whatever membrane it's going to

its rewrapped and repackaged unless

those fatty acids are then burned for

specific reasons that are oxidized so if

we so we know that Kalla microns can

goes is all these different tissues and

be delivered now let's look a little bit

more at

how fatty acid or how triacylglycerols

are constructed this is your storage

form of fat it's also how you eat most

of your fat most of the fat you consume

is in the form of tri so glycerides why

do we call it a try so glyceride simple

tri 3 fatty acids acyl acyl stands for a

long carbon hydrogen chain okay so try a

SIL glyceride glyceride is a glycerol

molecule okay so over here we have and

this is how they're stored adipose

mostly as as tri so glycerides alright

just it's literally your your fat cells

are literally just packed full of tri so

glycerides

and it's your storage unit alright so

you have your these are tri so

glycerides you had this glycerol head

here okay right now if like for example

we're talking about adipose and we're

gonna get to these situations in a

minute but you're in a situation where

you need to liberate fatty acids and get

them to another tissue let's say muscles

working hard muscle needs fatty acids to

burn for fuel well remember they're

gonna cross the barrier they're gonna go

out of the cell so they have to be

unpackaged so they can cross that

membrane and then repackaged okay so

what happens is there's a process that

cleaves this glycerol this glycerol

molecule okay so this leaves right and

you just get a glycerol molecule

terrible handwriting and that glycerol

can actually then be used for what's

called gluconeogenesis or it can just be

converted - it can be repackages another

tri so glyceride with other fatty acid

molecules okay they get a lot of stuff

in metabolism gets recycled but it also

can be used for for producing glucose

through gluconeogenesis in the liver so

you have whenever you have high rates of

fat oxidation or you're burning a lot of

fat you're also having a lot of glycerol

going to

liver because you're producing a lot of

glucose through gluconeogenesis because

it's usually when you're in a caloric

deficit so though just keep in mind

those two things usually go hand in hand

so now you've cleaved this glycerol

molecule and now you're going to be left

with three fatty acids it's actually the

way it works is the way it works

typically is actually when you when you

go through life pollicis you have first

a you'll have a reaction where there's a

diocese silver lipase where you have one

fatty acid a glycerol head and then two

fatty acids and then those that that two

fatty acids are then broken down and

then you have three fatty acids so it

goes two and one and then and then the

one that has two will be separated so

you're left with three fatty acids from

every triacylglycerol these fatty acids

can now cross this membrane out of the

cell can then be repackaged head to the

muscle and they can be used for energy

or they can go to the liver and they can

be repackaged and used for energy like

any any any tissue can do this all right

now that we kind of understand the

basics of how tri so glycerides and

fatty acids and those sorts of things

work and I do want to be specific you

don't always have to repackage fatty

acids when they're in the bloodstream

there are certain amount of fatty acids

that do stay in the bloodstream but for

the most part for transport and storage

they're packaged this tri so glycerides

so for our purposes that's how we're

going to think of it now let's talk

about what happens during different

situations okay let's say you ate

you were in a caloric surplus and you

ate a high-fat low-carbohydrate meal so

we have high fat low carb all right well

you're going to get a lot of these guys

right a lot of these chylomicrons right

because you ate high fat

all right but it was low-carb so you

don't have a lot of insulin insulins of

storage hormone so you're gonna have low

insulin so you're not you're burning

you're going to be burning a lot of fat

during this time okay so you're gonna

have an creat increase fat oxidation all

right even though you're in the surplus

you're still gonna be burning a lot of

fat because that's the fuel you're

providing if you're on a high-fat diet

but you're also going to have a lot of

fat storage okay so your so some of

these are going to go here there's gonna

be a lot of flux into adipose and

contrary to what a lot of people say you

don't need insulin to store fat as body

fat I'll say it again you do not need

insulin to store fat that's body fat

okay so yes you are burning more fat

you're also storing more fat the net

balance will be what we talked about

last video if you haven't seen the last

week I'll go back and encourage you to

go back and look at the net balance is

going to determine whether the overall

effect is fat loss or fat gain so if

you're in a caloric surplus the flux of

fat into adipose is going to be greater

than the amount you're burning even

though the rate at which you're burning

fat is going to be higher than if you

were on a high carb diet let me give you

another example so let's go with a high

carb diet relatively high carb diet

relatively high carb diet but during

caloric restriction so we just gave the

example of a high fat diet during a

caloric surplus let's look at a low fat

high carb diet during a caloric deficit

so so we're in negative energy balance

so we have high carb low fat okay that

means we're gonna have higher levels of

insulin

but we have less fatty acids right so we

had all those column icons coming in

well if you're on a low-fat diet you

don't have nearly as much okay now you

are not going to you're going to have

decreased fat oxidation the rate of fat

oxidation is going to be lower but

you're also going to be storing less fat

because you're not eating as much fat

okay

now people may say well you can store

carbohydrates as fat technically yes but

that's called de novo lipogenesis so

we'll just call and that happens in the

liver and that's called dnl de novo by

PO Genesis but the rate at which de novo

lipogenesis occurs is is that actually

winds up an adipose tissue so if we look

at glucose there goes that's in the

liver and it goes through de novo

lipogenesis and then comes out as well

it actually be like vldls and LDLs and

actually ends up getting stored in

adipose it is a very very very small

amount unless you are chronically on a

very high carb diet very low-fat de novo

lipogenesis is not going to account for

a significant amount of fat storage okay

now what is going to happen is since you

are higher insulin you're going to be

burning more carbohydrate less fat so

the fat that you do eat is more likely

to be stored as fat but since there's

less overall fat the how much actual

body fat you gain or lose is once again

going to be dependent on your total

energy balance okay so just because

insulin is high doesn't mean you're

storing a ton of fat because if you're

not eating much fat there's just not

that much fat to store okay now it does

mean that the fat you eat is more likely

to get stored so let me give you an

example let's just use arbitrary numbers

for a moment so let's say you're eating

100

of fat okay I'm sorry let's say 200

grams of fat that means your oxidation

is going to be way up fat oxidation carb

oxidation is going to be way down and

insulin is going to be low as long as

carbohydrates are low okay but you're

also going to be storing a lot of fat so

let's say we have 200 grams of fat we

eat all right we have low insulin

because it's low carbohydrate we have

highlights of fat oxidation because

we're eating a lot of fat we have low

bonds of carbohydrate oxidation because

we don't need to because there's not

that much carbohydrate available but

we've also got increased fat storage

because it's a very high calorie if

we're in a positive energy balance we're

gonna restore a lot even if we're in a

negative energy balance we'd be storing

a lot the difference if you're in a

negative energy balance is that the

amount that you are oxidizing will

exceed the amount you were storing I'll

say it again and a negative energy

balance the amount you're oxidizing will

exceed the amount you're storing so

let's say of this you're oxidized let's

say these are both negative energy

balances in this example all right

negative energy balance let's say you

burn I'm just using 170 grams and you

store 30 okay all right well you're in a

in a negative energy balance you're

gonna lose fat in that scenario but now

let's go to a high carb low fat all

right now you didn't store it you didn't

store much herbs yeah you didn't store a

great proportion of the fat you took in

you store like less than a sixth of it

because insulin was low right but let's

look at what happens if we eat 40 grams

of fat so we have decreased fat

oxidation let's say we ate that and then

like 200 grams of carbs but we're still

in the negative energy balance the

increased fat oxidation increased

carbohydrate oxidation but we have

decreased overall the

storage absolute fat storage but the

percentage of the fat you ate is going

to be stole more stored because of

increased insulin let me show you what I

mean so let's say let's say that hmm

70 percent of this got stored 70 percent

gets stored of that that is 28 grams and

only 12 grams was oxidized he said oh my

god

only 28 only 12 grams of fat was

oxidized you have the only 840 28 grams

of stored you actually stored less fat

if you're in a negative energy balance

you actually stolen less fat with the

high carb diet than you did with a low

carb diet now I'm not saying that's

exactly what happens I'm saying that if

you're in the same if you were in the

same energy balance in the same amount

of negative energy balance high carb

versus low fat high carb versus low carb

wouldn't make the difference on how much

fat you actually lose or gain it will

make a difference on the rates of fat

oxidation and the rates of fat storage

or the percentage of fat you store from

what you eat because insulin changes but

energy balance is always going to

dictate how much body fat you actually

lose now real quick

let's we've kind of talked about this a

little bit let's say you're in a

negative energy balance what what

happens right well if you're in an

overall negative energy balance where do

all this of whether you're eating high

carb low carb high fat low fat if you're

in a negative energy balance the flux is

going to be out of adipose tissue

because the amount of energy you're

expending is greater than the amount of

energy you are taking in and thus your

tissues are going to require you to

liberate fatty acids from storage in

order to continue to function because

the main goal of the body

you want to keep blood glucose stable

you also want to spare a muscle glycogen

the body's pretty stingy with glycogen

in order to do that what does it use to

spare that well it uses fat okay because

if you are burning more fat if you're

burning liberated fat you're not using

blood glucose you're not using muscle

glycogen as much for things you don't

need it for because muscle glycogen is

something that is a very specific

purpose that are very high intensity

short bursts right see that line

we got run from that line right you

don't want to be out I'm also glycogen

when you go to do that all right that's

why the body's very stingy with it same

token if you're in a caloric surplus

like we talked about last time if you're

in a positive energy balance even though

you may be if you're on a high-fat diet

again you may be burning more fat you're

also storing more fat because you're

taking so much more in okay and so the

flux is going to be into adipose tissue

all right guys I hope this has helped

you understand fat metabolism a little

bit more and how kind of fat fluxes

throughout the body we're going to go a

little bit more in depth in some of the

the coming series if there's some stuff

I'm missing or some stuff you'd like to

see me address ask it in the comment

below also here in a few weeks I have a

seminar coming up in Miami we've sold

out completely the VIP spots but we

still do have standard seminar spots and

I'm going to talk about some of this

stuff that I'm talking about here but in

person you can ask me questions it's

going to be awesome if you're interested

check out the description we'll put a

link below and we'll also put a

clickable link here in the video as well

thanks for watching guys I'll catch you

next time

you