Almost everyone at some point in their life will probably think about losing fat. So,
how do we go from this, potentially inches or centimeters thick of fat all the way down to this,
only a few millimeters thick. Well, in today's video, we're going to talk about
what really happens when your body burns fat. We'll look at the fat getting pulled
from the fat cells and potentially burned in other areas of the body.
We'll also discuss some myths or ideas about can we control where
we actually pull the fat from and we'll even about is there a best
type of exercise to lose fat? It's going to be a squishy one. So, let's do this.
[Intro]
When most people talk about losing fat, they're talking about losing subcutaneous fat. Sub just
means below and cutaneous means skin. So, it'd be this fat right here directly below
the skin and as you can see, it can be up to inches thick and this fat would cover up the
rectus abdominis right here, that six-pack muscle. Here's another example of some fat
that would cover up the deltoid muscle and so, the idea is partly aesthetics. People want to
have their muscles shine through and so, if the fat can be thinned out on top of the muscles,
then, those could more clearly shine through in all their stride glory.
Now, even though it might be nice to have thinner subcutaneous fats so that you could
see those muscles more clearly, that doesn't mean we shouldn't mention visceral fat. Visceral means
pertaining to internal organs. So, this would be the fat surrounding the organs. Here's the
abdominal cavity, up here is the thoracic cavity where you'd find the heart and lungs.
Now, this particular body or this dissection is actually a little bit more tricky to make
out specific structures and organs and that's because it has such a build up of this visceral
fat like look how thick and fatty this greater omentum is. You can see this thicker fatty
appendages coming off the intestine and that build up a visceral fat in between.
What's even more remarkable is the amount of visceral fat around the heart. Yes,
the heart is inside here and it's crazy to think about especially when you see what a normal amount
of visceral fat around the heart looks like. Now the visceral fat inside here is sometimes also
referred to as Deep Belly Fat because as it builds up inside, it can kind of push on your
abdominal and increase your waist circumference and the more we learn about this visceral fat,
the more we understand its links to certain health conditions - things like metabolic syndrome,
type 2 diabetes, high blood pressure, and other cardiovascular conditions to name a few.
But the nice thing about this visceral fat is we're going to actually lose it in a
very similar way to how we'd actually lose the subcutaneous fat. And with
this discussion about losing or burning fat, we're going to approach it from two
different perspectives. One, is what can we simply do to stimulate the fat loss and two,
this is kind of the more fascinating thing to me is if we actually look at what's going on
within the adipose tissue when we burn through it and thin it out - like where does it all go?
So, let's focus on that part first and then, we'll talk about some strategies that we can do
to stimulate the fat loss. Well, to do this, let's use an example like exercise of course. Let's say
we're going to focus on the quad muscles, those big muscles on the anterior thigh and those quad
muscles are exercising in need some extra energy and so, we can pull from the fat stores to get
this energy. We could pull from the fat over the abdomen. We could even pull from the fat that's
around the shoulder here but if we were to zoom in to this fatty tissue, we would see that it's
primarily made up of these cells called Adipocytes or adipose cells and probably not going to be too
big of a shocker that these adipose cells store fat and the fat is stored as triglycerides. That
is a glycerol bonded to three fatty acid chains and we need to break down these triglycerides
before we can actually pull the fat out of the cells and circulate it throughout the body.
And there's an important enzyme inside of your adipose cells called Hormone Sensitive Lipase
and this hormone sensitive lipase needs a little bit of help to get activated
and when we're exercising, we release certain chemicals like Epinephrine and Norepinephrine
which you maybe have heard of adrenaline or noradrenaline and also we release cortisol
and all three of these can help to activate this hormone sensitive lipase to start the
process called Lipolysis which is a fancy pants way of saying breaking down the fats.
And once we can break down these fats those fatty acids can be released into
the bloodstream and as an FYI, these fatty acids don't like water. Kind of you know,
fat versus water, they don't like each other. So, these fatty acids because our blood is
primarily water need to be transported with the protein. Primarily this protein is Albumin.
You can think of albumin is kind of like the taxi cab for your fatty acids and now,
once they're in the taxi cab, they can circulate to the blood and onto our working quadriceps. So,
now that we're in the bloodstream, some of those fatty acids could make it into the femoral artery
and take some of those branches off of the femoral artery into the working quadriceps.
And once it's in the quadriceps, those muscle fibers can take it in and funnel it into the
mitochondria to make ATP. So, it's kind of cool to visualize that whole process of getting to
the quadriceps but once we're in that mitochondria and making ATP, those of you who've taken biology
before might remember that if we're doing this in the mitochondria making ATP with fatty acids,
this is going to be done aerobically. Meaning there is enough oxygen present.
We only metabolize fats with oxygen, aerobically, whereas glucose or carbohydrates - glucose can be
metabolized anaerobically without oxygen but also with oxygen but to give you some numbers,
if we metabolize glucose with oxygen and funnel some of those products of glucose metabolism
into the mitochondria we can get about 32 to 36 ATP from that glucose. Whereas, the fatty acid,
like a common fatty acid that's metabolized, palmitic acid, that name is not really important,
so I don't know why I really mentioned it but that common fatty acid can yield almost 113 ATPs.
So, you might be thinking, "What's the catch? Why not just use fat for our
energy all the time? Why would we ever use carbs?" Well, as we just learned,
there are some logistics involved in utilizing fat for energy. We have to pull it from the storage,
get it in the bloodstream and transport it to a muscle or potentially another cell that
might utilize those fatty acids and they could be in a different body region all together.
So, there are multiple steps involved and there's this distance concern and yes, fats
make a lot of ATP per molecule but it just takes more time and from an exercise perspective, takes
about 10 to 20 minutes to really ramp up your fat metabolism during exercise and our muscles can't
actually store a lot of fat. So, again, we're mostly relying on at fat storage if we're going
to utilize fat for energy in the muscle tissue. Whereas our muscles are great at storing glucose
in the form of glycogen, glucose doesn't make as much ATP per molecule but it's right within the
muscle, ready and available and it's much faster to actually metabolize it and break it down.
So, bringing this full circle with what is actually happening inside our bodies
when we lose fat. As we consistently pull those fatty acids out of the adipose cells,
those cells will get smaller and smaller and smaller. Which will cause the overall tissue
to get thinner and thinner contributing to that overall loss of body fat and of course,
making it easier to see those wonderful skeletal muscles.
Now, keep in mind, we can apply the same principles that we've discussed to the
visceral fat. We can pull fatty acids from the visceral fat which will reduce the overall amount
within those body cavities and the question that people will often have with fat loss is
"can you control where you pull the fat from based on exercise choices?" Like for example,
if you were to do a whole bunch of crunches to work the rectus abdominis, could you get your
body to preferentially pull from the fat above the belly to make this muscle more
visible and unfortunately, there's no consistent evidence that I've ever seen to support that.
It's not like you could go do all these glute exercises and clench your butt cheeks all day
long in between to try to tell your body "hey, just pull fat from around my glutes so you can see
that a little bit better"... not really going to happen. Now, that doesn't mean that you couldn't
make a muscle be a little bit more visible getting it bigger. Like for example, if you did
a whole bunch of crunches and these muscle fibers underwent hypertrophy or they just literally got
bigger, they might be a little bit more visible just because the muscle was literally larger
underneath but that wasn't because you told your body exactly where it could pull the fat from.
The key is consistent overall fat loss and the muscles will become more visible as body
fat percentage continues to decrease. And the last thing we need to discuss is this
idea of a possible best type of exercise for burning fat. Does that actually exist? Like
is there a true fat burning zone that people should stay in if their main goal is fat loss?
Well, it depends what you mean by a "fat burning zone". Yes, there is a zone or level of exercise
intensity where you burn a higher percentage or proportion of fats compared to carbohydrates and
so you might initially think, yes, let's exercise in that zone if the goal is fat burning. Well,
proportions are one thing but we also have to look at the total overall number
or amount of fat burned and let me give you an example to help illustrate this.
Let's say we work in that fat burning zone and burn a higher proportion of
fats compared to carbohydrates and we burned a total of 100 calories during
this light exercise session and 70% of those came from fats and only 30% came
from carbs and since we're using nice round numbers, that means 70 calories from fats,
30 calories from carbohydrates and again, you might think that's where we want to be.
Well, if we did another session on another day that have higher intensity, we would have
to start shifting our utilization from fats to carbohydrates. As intensity increases, we just
don't have enough time to mobilize and utilize those fats so again, we have to start shifting to
carbohydrates but in that session, we burn a total of 500 calories and 70% came from carbohydrates
and only 30% from fat. And so again, you might, well, I just burned less fat. Well, no, because
30% of 500 is 150 calories from fat. Whereas our previous example, we only burned 70 calories.
Now, don't quote me on those exact numbers in those previous examples.
I was mostly using nice round numbers to help illustrate the point but if you like
some more details and nitty-gritty numbers, I actually made a chart in a previous video
where I made exact calculations of the proportions of fats burned compared to
carbohydrates in the fat burning zone as well as at other exercise intensities.
So, if you're interested in that, I'll link that here but the last thing I want to mention about
this idea of some perfect or best type of exercise for fat loss is if we were to look
multiple different types of athletes - looking at like runners and cyclists, basketball players,
soccer players, tennis players, weightlifters, even like a wide receiver in football because yes,
there are certain positions in football and other sports where some extra fat or
weight might be beneficial but for the most part, if we look at these different types
of athletes, yes, we would see some differences in muscular development.
Certain sports and training modalities would stimulate more like muscular endurance type
adaptations and the muscles wouldn't get very large where other types of and training,
the muscles would get stimulated to increase in size and everywhere in between. So,
we would see that difference in muscular development but one thing that these
athletes would share in common is that they don't carry a lot of extra fat around.
So, what we can glean from this is that there is not one best way to do this. There
are multiple ways to be successful in burning and losing fat and so,
one of the beautiful things that I think is about exercise is the amount of choices
that we have and we are more likely to consistently participate in exercise
and therefore have successful fat loss if we do exercise that we actually like doing and enjoy.
So, if you are the one that likes to do long distance running, you could lose fat doing
that. If you like higher intensity training and intervals, you could lose weight and fat
doing that. If you like weight training or a combination of weight training and cardio,
you can be successful and obviously participating in your sports could help with this.
What most of the data is suggesting is that it's not about focusing so much on
this proportion of how much fat compared to carbs I burn, it's still more about the
overall caloric expenditure. And yes, losing weight and fat is easier said than done in
certain situations. There are things we can control like genetics, age, even hormones,
and other things but I always say to patients, let's do try to focus on what we can control
and we can control how many calories we burn and how many calories we bring in.
So, if we can be successful at burning more calories than we bring in or ingest, then,
we can have some potential success in losing fat and losing weight and then once we get to
a place where we're happy with, then we can adjust and those inputs can equal outputs.
So, hopefully you learn something new and useful about how the body burns fat
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We'll also include that link and the info in the description below and with my typical sign off,
thanks for watching everyone. Like and subscribe if you feel the need. Burn some
extra calories by frantically writing some comments below and we'll see you next time.