May 28, 2025 • 24 mins
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--
Confused about "fat burning" versus actual fat loss? Learn why you can be "burning fat" during workouts while not losing body fat.
Today I break down the difference between fat oxidation (using fat for fuel) and fat loss (reducing stored body fat) that most people misunderstand.
You'll discover how the Randle Cycle affects metabolism, why fasted cardio isn't the magic bullet you've been told, and what really determines whether your body sheds fat... regardless of what fuel you're burning in the moment.
We clear up some misunderstandings about low-carb diets (keto and carnivore), being fat adapted, and what's actually most important for fat loss.
Main Takeaways:
- Fat oxidation (burning fat for fuel) and fat loss (reducing stored body fat) are completely different physiological processes
- The Randle Cycle explains why carbs temporarily suppress fat burning, but this doesn't make low-carb diets superior
- Low-carb diets increase fat oxidation but don't produce better fat loss results when calories and protein are equated (in fact, sometimes the opposite is true)
- For successful fat loss, focus on what directly influences body composition
- Adopting an engineering mindset means optimizing for outcomes (fat loss) rather than processes (fat oxidation)
Timestamps:
0:01 - Why burning fat doesn't always mean losing fat
3:14 - Fat oxidation vs. fat loss
5:09 - The Randle Cycle and fuel selection (glucose vs. fatty acids)
9:36 - Low-carb diets and fat loss
13:42 - Any benefits of fasted cardio (beyond fat burning)?
15:04 - What actually determines fat loss
16:25 - Optimize for outcomes, not processes
17:55 - What you measure vs. what matters = more freedom
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Philip Pape (00:01):
If you've ever been confused about why you can burn
fat during a workout but notactually lose body fat, or why
low-carb diets promise to keepyou fat-adapted in fat-burning
mode, yet sometimes fail todeliver results, this episode is
for you.
Today, we're uncovering thedifference between fat oxidation
and actual net fat loss thatalmost everyone misunderstands.
(00:25):
You'll learn how the RandallCycle affects your metabolism,
why fasted cardio might not bethe magic bullet you think it is
, and what really determineswhether you lose fat, regardless
of what fuel your body isburning in the moment.
Welcome to Wits and Weights,the show that helps you build a
(00:51):
strong, healthy physique usingevidence, engineering and
efficiency.
I'm your host, philip Pape,certified nutrition coach, and
today we're looking at one ofthe most misunderstood concepts
in fitness, and that is thedifference between fat burning,
or the technical term oxidation,and fat loss, which is
(01:11):
literally losing fat from yourbody generally by losing weight
and holding on to muscle.
This confusion is often led toquestions that come up on a
daily basis, especially when Iwrite or do an episode about
carbs or low-carb diets, wherepeople say, well, I'm
fat-adapted or I burn more fatbecause I'm low-carb, and it's a
(01:32):
complete misunderstanding ofwhat's actually going on, and so
people chase down ineffectivediets, potentially restrictive
diets that are miserable.
They waste their workouts bynot training the right way and
then they get frustrated.
They can't figure out whythey're not seeing results
despite doing the things you'resupposed to do.
To quote unquote burn fat.
The reality is that fat burningand fat loss are two completely
(01:54):
different physiologicalprocesses.
It's unfortunate that theysound very similar, but if we
can understand the distinction,it will help you improve your
body composition because you'llbe informed on whether you're
putting your energy in the rightplace.
So by the end of the episode,my goal is to help understand
why things like low-carb diets,fasted cardio, other popular
(02:17):
quote-unquote fat-burningstrategies might not be working
as promised.
They might have somemisdirection in there, and what
you should focus on instead ifyou really want the results.
Before we dive in, I do have aquick favor to ask If you enjoy
today's episode.
Take a moment to leave afive-star review on Apple
Podcasts.
Each month, I'm randomlyselecting one reviewer and
(02:39):
they're going to receive a freeprotein supplement of their
choice.
This is my way of saying thankyou for supporting the show, and
the reviews help other peoplediscover this show, why people
like it and how it might helpthem to escape the sea of
confusion, of misinformationthat's out there.
So again, go to Apple Podcasts,submit a five-star review, do
(03:00):
it on your iPhone or Appledevice, and if you don't have
that device or don't use anApple podcast, feel free to
throw in a rating on Spotify, orjust shoot me a message and say
, hey, show's great, thanks fordoing it, and that'll make my
day All right.
So let's get into the topic andstart by defining what we're
talking about.
The confusion between fatoxidation and fat loss is,
(03:23):
honestly, at the heart.
It is at the root of so manypopular strategies today that
are misguided, oftentimesbecause of this very thing.
So what is the difference?
Fat oxidation when we say fatburning, right, that is a
metabolic process where yourbody breaks down fat molecules
to produce energy, and that'swhat typically mean when they
(03:45):
talk about burning fat duringexercise or following a diet or
in any situation, fastedtraining, etc.
It's essentially the use of fatas fuel, which is great.
We want to do that.
We want to use our fat,especially if you're trying to
lose it, which leads me to fatloss.
See, fat loss actually is thereduction of stored body fat
over time, and this is what mostof us are actually trying to
(04:08):
achieve.
When we say we want to lose fat, it's not that we want to just
burn fat in a vacuum.
We want to lose the net fatstored on our body and we want
to add more muscle.
We want to lose fat right.
We want to look better, leaner,more fit, we want to be
stronger, more healthy, moreathletic all of the things.
So I think what most peoplemiss is that these two processes
burning fat for fuel in themoment versus reducing stored
(04:31):
body fat over time don't alwaysgo hand in hand.
In fact, oftentimes they don'tgo hand in hand.
They're different, independentthings going on.
You can oxidize plenty of fatduring your workouts.
Going on, you can oxidizeplenty of fat during your
workouts, but not lose body fatfrom your body.
Conversely, you can beprimarily burning carbohydrates
during exercise, yet still losesignificant amounts of body fat
(04:55):
over time, and so thisdisconnect leads to confusion,
especially around low carb diets, keto carnivore, fasted
training all sorts of strategiesyou know, fat burning workouts
that promise to maximize fatburning.
So that's why I'm creating thisepisode.
Now let's take a look at thephysiology first.
I think that's a great place tostart and there's something
called the Randall cycle.
(05:15):
Now I heard about this a longtime ago.
I kind of forgot about it,specifically by name, until a
YouTube commenter mentioned itand they said hey, if this is
all true, if low carb dietsmight not be beneficial for a
lot of people, um, why, whatabout the cycle?
Why, why?
Why isn't that the reason lowcarb diets would be so
beneficial?
So the Randall cycle it's alsoknown as the glucose fatty acid
(05:39):
cycle.
It was first described byPhilip Randall in the sixties
1963.
And it describes therelationship between
carbohydrate and fat metabolismin our bodies.
So essentially it explains thatwhen your body has both glucose
and fatty acids available right, glucose from carbs, fatty
acids from fats available asfuel they compete with each
(06:01):
other.
So when glucose levels are high, your body's going to
preferentially burn glucose andsuppress fat oxidation right, so
it's burning glucose becauseit's there instead of fat.
When glucose levels are low,your body's going to shift to
burning more fat.
Now, before I move on, noticewhat this means.
This means when someone saysglucose is the body's preferred
energy source.
That is a true statement,meaning it will burn that if
(06:23):
it's available first, then itwill burn fat.
But of course, if you depriveyourself of carbohydrates, it
has no choice but to burn fat.
So let's continue.
So this is kind of a reciprocalin a way, but it is a little
bit asymmetric.
Your body's designed to usewhatever fuel's most readily
available, but it's going to gofor glucose first if it's
available.
That's why it's slightlyasymmetric.
(06:43):
But it's going to preservewhatever's in shorter supply
effectively for when it might beneeded later.
And that's why the low carbadvocates and the fasted cardio
enthusiasts where they come in,because they on one hand
correctly note that high insulinlevels from carbohydrate
consumption suppresses fatoxidation, but then they
conclude that to lose body fatyou should minimize carbohydrate
(07:07):
intake to stay in that fatburning mode as much as possible
.
But here's the flaw Veryimportant what matters for fat
loss isn't the fuel you'reburning at the moment, but your
overall energy balance over time.
That's the key distinction here.
So guess what's happening on alow-carb diet?
You're eating more fats.
In other words, you are takingin the same amount of energy.
(07:29):
You're just burning a differenttype of energy because you have
more of it.
That's all you're doing, right?
Whereas a person with moderateto high carbs is eating less fat
.
So they're burning more carbs.
It all nets out to the samething in terms of energy balance
, and the Randall cycle simplyaddresses the fuel selection.
You know you have a fuelselection dial.
(07:50):
Am I going to burn glucose oram I going to burn fat?
It's not the chronic change inyour fat mass on your body.
So if I gave you a concreteexample, let's say you're eating
a low carb, high fat diet,right, keto, carnivore, we know
them.
Your insulin levels are gonnabe relatively low and you'll be
primarily oxidizing fat for fuelthroughout the day.
And if you're on keto, youmight be to the point of past
(08:13):
ketosis where you are whatpeople call fat-adapted, where
you just that's always whatyou're doing.
So that's great.
You're burning fat, right,you're burning fat right.
But if your total calorieintake exceeds your expenditure,
you're still going to gain bodyfat, even though you're
primarily using fat as fuel,because the dietary fat you
consume but don't immediatelyburn is going to get stored.
(08:35):
So you're just eating more fatand that all that extra fat is
now going to get stored, whereaswith the other guy who's eating
a balanced diet, the extracarbs are going to get or the
fat's gonna get stored while youburn the carbs, it doesn't
matter.
The energy nets out, right.
So again, conversely, if youeat a higher carb diet but you
maintain a calorie deficit,right?
So this is a lot of the peopleI work with who want a more
(08:56):
flexible diet, more balanced,where they can enjoy their carbs
, but then we put them into acalorie deficit, guess what?
You're still going to burnglucose, primarily during and
after meals because of the carbs, which suppresses your fat
oxidation, but over a 24-hourperiod, your body's still going
to need to tap into those fatstores once it runs out of
glucose to meet its energy needs, resulting in net fat loss,
(09:19):
just because you don't haveenough energy period Total
energy coming in.
And that happens even thoughyou're not maximizing fat
burning.
Right?
Fat oxidation at every moment.
And this distinction becomesimportant when we look at how
this applies to specificstrategies.
Let's start with low carb diets.
I know I've already hammered ita little bit, but I want to go
(09:40):
one level deep.
And then there's absolutely noquestion that reducing carb
intake shifts your metabolismtoward greater fat oxidation.
We know that.
I'm not going to dispute that.
That's a fact.
Studies consistently showhigher rates of fat oxidation
both at rest and during exercisein people following low-carb
(10:01):
diets, and that is what theRandall Cycle would predict, but
it does not translate to betterfat loss outcomes, because when
calories and protein arecontrolled, the answer is an
emphatic no, there is nodifference.
A meta-analysis by Hall and Guoin 2017 found that low-fat diets
actually produce slightly morefat loss than low-carb diets
(10:22):
when calories were equated.
Now, part of the reason forthat could be because, guess
what?
Your body requires more energyto digest carbs than it does fat
, just like it requires moreenergy to digest protein than
carbs or fat.
So that could be one of thereasons why.
There's probably other reasonsbehind there we're not going to
get into today, likeanti-catabolism, supporting your
(10:42):
training, et cetera.
Similarly, and also your stressand metabolism.
Okay, enough of that.
But similarly, there was astudy.
It was a highly controlledmetabolic ward study.
Everybody locked in one placeand fed a controlled diet.
This is by Hall in 2015,.
Found that a low-fat diet ledto slightly more body fat loss
(11:02):
than a low-carb diet, despitethe low-carb diet showing
increased fat oxidation.
Now, my point isn't to say thatlow-fat's better than low-carb
diet showing increased fatoxidation.
Now, my point isn't to say thatlow-fat's better than low-carb.
It's to say that there's noadvantage to low-carb when it
comes to fat oxidation and fatloss.
Right, yes, you have more fatoxidation, but you're not going
to lose any more fat.
Now it doesn't mean low-carbdiets can't be effective for fat
(11:24):
loss either.
That's what I want to say.
They can be, but not becausethey maximize fat oxidation.
They work for most peoplebecause, number one, you're
going to increase your proteinintake, which is something
everybody needs to do topreserve muscle mass.
Number two, it can improveappetite control in some people.
Some people actually gethungrier on higher carbs.
So having the higher fats andprotein helps with satiety
(11:45):
Totally true phenomenon thathappens.
Number three, you reduce waterretention, and this is just the
appearance of much more rapidprogress early on.
So when somebody says I went onketo and I lost 10 pounds, yeah
, most of that's water weight.
And then, number four, it makesyour diet, I'll say, simpler in
terms of food choices, whichwill have the illusion of making
(12:06):
it easier to adhere, andactually does so for some people
, but for most people itactually makes it harder
long-term because you'reavoiding things that you might
otherwise want to enjoy.
But again, there are exceptions.
There are some people who arelike, yeah, I'm happy as a clam
on my very limited set of foodchoices, that's fine, okay.
The point here is theeffectiveness of a low-carb diet
for fat loss doesn't have to doanything at all with increased
(12:26):
fat oxidation and has everythingto do with energy balance.
Always comes back to that, andthe same principle applies then
to fasted cardio.
I want to talk about fastedcardio.
This is an interesting one,because it is true that
exercising in a fasted state,especially first thing in the
(12:47):
morning before breakfast,results in higher fat oxidation
during the workout.
And if you have not recentlyconsumed carbs to raise insulin,
your body relies even moreheavily on fat.
So if you never eat carbs, ofcourse you're fat adapted.
It's just going to be burning aton of fat.
But this again acute increase,right?
(13:09):
This energy selection processtoward fat burning doesn't
translate to greater fat lossover time, for all the reasons
we've already discussed, butI'll just throw another study at
you by Schoenfeld, a guy I verymuch respect in the space.
This was from 2014,.
Found no difference in fat lossbetween women performing fasted
cardio versus fed cardio whentotal calorie intake was
(13:30):
controlled.
So what matters is total energydeficit if you're going for fat
loss and not whether thatdeficit comes from fat or
carbohydrate oxidation.
Right Now, that's not to sayfasted cardio, has no benefits
at all.
Again, I love nuance andindividualizing here.
The first thing that comes tomind is it's more time efficient
(13:51):
.
For some people.
You get up in the morning andyou go right.
The other thing is it mightimprove your ability to switch
between fuel sources, and thenthis is an interesting one.
Whether that's beneficial inany other way is, I think, still
up for debate, but it does do.
It does potentially do that itmight help you feel better if
you don't like exercising, youknow, with food in the morning
(14:13):
or you don't have time to eatfood, you know there's lots of
like logistical and preferencereasons for this.
And then it might have benefitsfor certain populations with
certain metabolic disorders.
I never disclaim that that's apossibility.
But if you're just trying tolose fat, you know you have to
focus on creating a sustainableenergy deficit, and our last
episode was all about that.
(14:34):
It was all about fat loss.
So go listen to that if youmissed it.
And this happens through yournew training.
New training this is thecombination of nutrition and
training called new training,through your nutrition and
training approach.
Your lifestyle is going to beway more impactful than worrying
about whether you're maximizingfat oxidation, and by way more
I mean like all of it.
(14:54):
In other words, extra fatoxidation from low carb or
faster training, whatever isgoing to make not a lick of
difference in your overall fatloss relative to what the other
lifestyle changes will.
So if acute fat burning, fatoxidation, is not the key to fat
loss, what is Well?
Again, it comes down to basicthermodynamics and energy
balance.
To lose body fat, you have tocreate an energy deficit where
(15:17):
you consume fewer calories thanyou expend.
That is it, and that forcesyour body to mobilize whatever
energy is stored and availableright, preferentially from fat
tissue, to meet its needs.
And again, if you don't haveenough calories coming in and
you're still consuming carbs,it's going to go to carbs and
then it's going to go to fat,but the net effect is the same,
right.
So the key factors here arethen the total calorie intake
(15:40):
versus your expenditure, yourprotein intake, resistance,
training and the ability toadhere to your diet.
Of course, recovery is massiveas well All the things I spoke
about in the last episode, thethree plus three model of fat
loss.
So go for, listen to that, for adeep dive.
And none of these things dependon maximizing fat oxidation at
(16:01):
any given moment.
That is just energy systems.
That is just your body sayinghey, I'm efficient, you need
energy, I need to give youenergy.
Let's see what's on the menutoday.
Is it glucose or is it fat?
It doesn't matter, it's allenergy to your body, right.
And at the end of the day, thedeficit and the energy balance
is what matters.
Which brings me to an importantengineering principle that
applies perfectly here Optimizefor the outcome, not the process
(16:24):
.
Now, you might be confused whenI say this, because I talk all
the time about how important theprocess is.
But if we think of engineeringwhere we focus on the end result
, the product, the system, theservice, the software, we then
reverse, engineer and workbackward to determine the most
efficient way to achieve it.
We don't get caught up inoptimizing I'll say, individual
(16:47):
steps if they don't materiallyaffect the final outcome.
We care about an efficientprocess that gets us to the
outcome right, and then we focuson the process, but we optimize
for the outcome and for fatloss.
This means focusing on thefactors that directly influence
body composition over time, noton momentary metabolic processes
(17:08):
that have little impact on theend result, like I'm not going
to tell you to drink more coffeebecause it might have a slight
thermo thermic boost in yourmetabolism.
That's not an efficient way tooptimize the process.
Think of it like this If you'retrying to save money, what
matters is the differencebetween your income and your
spending right, not whether youpay for a purchase with cash or
credit.
That's effectively what this isGlucose or fat, cash or credit
(17:31):
doesn't matter.
It's all coming from yourenergy budget.
So, with fat loss, what mattersis the difference between your
intake and expenditure, notwhether you're burning fat
versus carbs at a given moment.
And now I want to address onemore aspect of this topic that
causes a lot of confusion, andthat is the difference between
what we measure and what matters.
And this goes back to what Ijust said about optimizing for
(17:54):
the outcome.
When people follow low-carbdiets or they do fasted cardio
or any of these fat-burningtricks, they often point to
indicators of increased fatoxidation as proof that they're
working.
They might mention ketones Look, look at all the ketones in my
urine or blood work.
They might mention a lowerrespiratory quotient RQ during
exercise oh, I'm burning morefat because my RQ is lower.
(18:16):
They might say that they arefat adapted.
Oh, I feel great.
I have steady energy, I don'thave crashes, all my
inflammation has gone away.
You guys seen these posts bypeople.
I went on carnivore andeverything got solved.
Well, these measurements doindeed confirm something they
increase.
They confirm increased fatoxidation.
They might even confirm thatyou have um, eliminated
something that didn't work foryou and then you just never
(18:38):
added, added back the thingsthat do.
That's fine, that's cool.
You start where you're at, butthey don't predict better fat
loss outcomes.
They're measuring individual,independent aspects of the
process rather than the result.
And once you see that theydon't actually produce fat loss
and you reverse engineer it, yousay maybe it's not necessary to
(18:58):
focus on fat oxidation.
In the end, what I actuallyfocus on is measuring and
tracking progress toward the endgoal by optimizing the process.
For that you know my change inbody composition over time, your
, your, your trend, weight, yourmeasurements, your photos, your
, maybe even body fat.
I'm not a big fan of measuringbody fat, but there are ways to
do body fat trends that arehelpful.
Um, has your strength gone upor down?
(19:20):
Have you?
How are your energy levels,your hunger, your well-being?
And yeah, these are outcomes.
And by outcome I don't justmean at the end of the day, did
you lose 20 pounds six monthsfrom now, I mean all the things
that come from your day-to-dayactions in optimizing the
process.
Are you adherent to yourcalorie and protein targets?
That is an outcome of theprocess of being consistent in
(19:42):
hitting your targets.
So, anyway, I can go on, but Ithink it's important to
understand that difference Fatburning, fat loss two different
things.
And this gives you more freedomonce you understand that, with
your nutrition, with yourtraining or with your new
training, just kidding.
And that's what matters, right,what matters is your energy
deficit.
It makes it simple.
It actually makes it reallysimple, and I'm kind of hitting
(20:04):
again on some of the messagesfrom the last episode which,
again, I highly recommendlistening if you didn't.
But when you know that whatmatters is the energy deficit,
it actually frees you in a lotof ways.
It frees you with your mealtiming.
You could eat when yourschedule and preferences match.
You can include carbs I mean,that's the big one that comes to
mind If you enjoy them, if theyfuel your training, if you
(20:25):
tolerate them absolutely.
It informs your training.
You're not going to be choosingmovement or training for fat
burning.
You're going to do somethingthat supports your real goal,
which is strength, muscle,athleticism, whatever, and then
you can find a diet that worksfor you, not based on some
metabolic theory that doesn'tactually produce the results, it
(20:46):
doesn't optimize for the resultand that's much more enjoyable,
in my opinion and they're goingto produce better results
because you're going to sustainthem.
That's what we're going for,right?
The most optimal diet for fatloss is that one that you can
stick with.
I can say that to the cows comehome.
Some people won't accept it.
They want to cut their foods.
They want to claim that fatadapted makes them superior in
some way for fat burning, and itdoesn't right.
(21:07):
Energy balance is where it's at.
All the other things areimportant for other reasons for
health, for strength, et cetera.
But today we wanted to talkabout the difference between fat
loss and fat burning, right?
So, to recap, fat oxidationburning fat for fuel and fat
loss, which is reducing storedbody fat, are distinct
physiological processes thatdon't necessarily go hand in
(21:27):
hand.
The RAND cycle look it up ifyou'd like explains why carb
intake suppresses fat oxidation,but it doesn't prevent fat loss
, because it's the energybalance that matters.
Low-carb diets, fasted cardiothey do increase fat oxidation,
but they don't produce any morefat loss and some studies show
they actually produce less.
(21:48):
For successful fat loss, you'regoing to focus on the factors
that influence body compositionover time.
That's what's important for fatloss.
Go listen to my last episode,the three plus three model of
fat loss, for details.
And then adapting anengineering mindset like we do
here, means optimizing for theoutcomes over days, weeks and
months rather than optimizingfor the process itself.
The bottom line is that I don'twant you to get caught up in
(22:11):
chasing fat burning, becausewhat's going to happen is you're
going to do restrictive, weird,cult-like approaches.
I'm sorry to put it that way,but you are.
You're going to fall into atribe.
That's all about fat burningand you're actually not going to
lose fat.
And I want you to lose fatright.
I want you to lose fat doingsomething that works for you,
that feels great, that's goodfor your body, your preferences,
your lifestyle, that's it Allright.
(22:32):
If you found today's episodehelpful, please take a moment to
leave a five-star review onApple Podcasts and be entered
for a random selection of onewinner each month to receive a
free protein supplement of theirchoice.
And it means a lot to me whenpeople let me know what they
think of the show, and it meansa lot to others when they
understand what they're gettinginto, for better or worse.
(22:54):
Just go to Apple Podcasts onyour Apple device, search for
Wits and Weights, click ratingsand reviews and leave your
feedback.
Takes about one minute, but itmakes a huge difference, so I
really appreciate it.
Until next time, keep usingyour wits lifting those weights
and remember, when it comes tofat loss, it is not about
burning fat in the moment.
It's about creating theconditions for your body to lose
fat over time.
(23:15):
This is Philip Pape and you'vebeen listening to Wits and
Weights.
I will talk to you next time.
Bye.
If you've ever been confused about why you can burn
fat during a workout but notactually lose body fat, or why
low-carb diets promise to keepyou fat-adapted in fat-burning
mode, yet sometimes fail todeliver results, this episode is
for you.
Today, we're uncovering thedifference between fat oxidation
and actual net fat loss thatalmost everyone misunderstands.
(00:25):
You'll learn how the RandallCycle affects your metabolism,
why fasted cardio might not bethe magic bullet you think it is
, and what really determineswhether you lose fat, regardless
of what fuel your body isburning in the moment.
Welcome to Wits and Weights,the show that helps you build a
(00:51):
strong, healthy physique usingevidence, engineering and
efficiency.
I'm your host, philip Pape,certified nutrition coach, and
today we're looking at one ofthe most misunderstood concepts
in fitness, and that is thedifference between fat burning,
or the technical term oxidation,and fat loss, which is
(01:11):
literally losing fat from yourbody generally by losing weight
and holding on to muscle.
This confusion is often led toquestions that come up on a
daily basis, especially when Iwrite or do an episode about
carbs or low-carb diets, wherepeople say, well, I'm
fat-adapted or I burn more fatbecause I'm low-carb, and it's a
(01:32):
complete misunderstanding ofwhat's actually going on, and so
people chase down ineffectivediets, potentially restrictive
diets that are miserable.
They waste their workouts bynot training the right way and
then they get frustrated.
They can't figure out whythey're not seeing results
despite doing the things you'resupposed to do.
To quote unquote burn fat.
The reality is that fat burningand fat loss are two completely
(01:54):
different physiologicalprocesses.
It's unfortunate that theysound very similar, but if we
can understand the distinction,it will help you improve your
body composition because you'llbe informed on whether you're
putting your energy in the rightplace.
So by the end of the episode,my goal is to help understand
why things like low-carb diets,fasted cardio, other popular
(02:17):
quote-unquote fat-burningstrategies might not be working
as promised.
They might have somemisdirection in there, and what
you should focus on instead ifyou really want the results.
Before we dive in, I do have aquick favor to ask If you enjoy
today's episode.
Take a moment to leave afive-star review on Apple
Podcasts.
Each month, I'm randomlyselecting one reviewer and
(02:39):
they're going to receive a freeprotein supplement of their
choice.
This is my way of saying thankyou for supporting the show, and
the reviews help other peoplediscover this show, why people
like it and how it might helpthem to escape the sea of
confusion, of misinformationthat's out there.
So again, go to Apple Podcasts,submit a five-star review, do
(03:00):
it on your iPhone or Appledevice, and if you don't have
that device or don't use anApple podcast, feel free to
throw in a rating on Spotify, orjust shoot me a message and say
, hey, show's great, thanks fordoing it, and that'll make my
day All right.
So let's get into the topic andstart by defining what we're
talking about.
The confusion between fatoxidation and fat loss is,
(03:23):
honestly, at the heart.
It is at the root of so manypopular strategies today that
are misguided, oftentimesbecause of this very thing.
So what is the difference?
Fat oxidation when we say fatburning, right, that is a
metabolic process where yourbody breaks down fat molecules
to produce energy, and that'swhat typically mean when they
(03:45):
talk about burning fat duringexercise or following a diet or
in any situation, fastedtraining, etc.
It's essentially the use of fatas fuel, which is great.
We want to do that.
We want to use our fat,especially if you're trying to
lose it, which leads me to fatloss.
See, fat loss actually is thereduction of stored body fat
over time, and this is what mostof us are actually trying to
(04:08):
achieve.
When we say we want to lose fat, it's not that we want to just
burn fat in a vacuum.
We want to lose the net fatstored on our body and we want
to add more muscle.
We want to lose fat right.
We want to look better, leaner,more fit, we want to be
stronger, more healthy, moreathletic all of the things.
So I think what most peoplemiss is that these two processes
burning fat for fuel in themoment versus reducing stored
(04:31):
body fat over time don't alwaysgo hand in hand.
In fact, oftentimes they don'tgo hand in hand.
They're different, independentthings going on.
You can oxidize plenty of fatduring your workouts.
Going on, you can oxidizeplenty of fat during your
workouts, but not lose body fatfrom your body.
Conversely, you can beprimarily burning carbohydrates
during exercise, yet still losesignificant amounts of body fat
(04:55):
over time, and so thisdisconnect leads to confusion,
especially around low carb diets, keto carnivore, fasted
training all sorts of strategiesyou know, fat burning workouts
that promise to maximize fatburning.
So that's why I'm creating thisepisode.
Now let's take a look at thephysiology first.
I think that's a great place tostart and there's something
called the Randall cycle.
(05:15):
Now I heard about this a longtime ago.
I kind of forgot about it,specifically by name, until a
YouTube commenter mentioned itand they said hey, if this is
all true, if low carb dietsmight not be beneficial for a
lot of people, um, why, whatabout the cycle?
Why, why?
Why isn't that the reason lowcarb diets would be so
beneficial?
So the Randall cycle it's alsoknown as the glucose fatty acid
(05:39):
cycle.
It was first described byPhilip Randall in the sixties
1963.
And it describes therelationship between
carbohydrate and fat metabolismin our bodies.
So essentially it explains thatwhen your body has both glucose
and fatty acids available right, glucose from carbs, fatty
acids from fats available asfuel they compete with each
(06:01):
other.
So when glucose levels are high, your body's going to
preferentially burn glucose andsuppress fat oxidation right, so
it's burning glucose becauseit's there instead of fat.
When glucose levels are low,your body's going to shift to
burning more fat.
Now, before I move on, noticewhat this means.
This means when someone saysglucose is the body's preferred
energy source.
That is a true statement,meaning it will burn that if
(06:23):
it's available first, then itwill burn fat.
But of course, if you depriveyourself of carbohydrates, it
has no choice but to burn fat.
So let's continue.
So this is kind of a reciprocalin a way, but it is a little
bit asymmetric.
Your body's designed to usewhatever fuel's most readily
available, but it's going to gofor glucose first if it's
available.
That's why it's slightlyasymmetric.
(06:43):
But it's going to preservewhatever's in shorter supply
effectively for when it might beneeded later.
And that's why the low carbadvocates and the fasted cardio
enthusiasts where they come in,because they on one hand
correctly note that high insulinlevels from carbohydrate
consumption suppresses fatoxidation, but then they
conclude that to lose body fatyou should minimize carbohydrate
(07:07):
intake to stay in that fatburning mode as much as possible
.
But here's the flaw Veryimportant what matters for fat
loss isn't the fuel you'reburning at the moment, but your
overall energy balance over time.
That's the key distinction here.
So guess what's happening on alow-carb diet?
You're eating more fats.
In other words, you are takingin the same amount of energy.
(07:29):
You're just burning a differenttype of energy because you have
more of it.
That's all you're doing, right?
Whereas a person with moderateto high carbs is eating less fat
.
So they're burning more carbs.
It all nets out to the samething in terms of energy balance
, and the Randall cycle simplyaddresses the fuel selection.
You know you have a fuelselection dial.
(07:50):
Am I going to burn glucose oram I going to burn fat?
It's not the chronic change inyour fat mass on your body.
So if I gave you a concreteexample, let's say you're eating
a low carb, high fat diet,right, keto, carnivore, we know
them.
Your insulin levels are gonnabe relatively low and you'll be
primarily oxidizing fat for fuelthroughout the day.
And if you're on keto, youmight be to the point of past
(08:13):
ketosis where you are whatpeople call fat-adapted, where
you just that's always whatyou're doing.
So that's great.
You're burning fat, right,you're burning fat right.
But if your total calorieintake exceeds your expenditure,
you're still going to gain bodyfat, even though you're
primarily using fat as fuel,because the dietary fat you
consume but don't immediatelyburn is going to get stored.
(08:35):
So you're just eating more fatand that all that extra fat is
now going to get stored, whereaswith the other guy who's eating
a balanced diet, the extracarbs are going to get or the
fat's gonna get stored while youburn the carbs, it doesn't
matter.
The energy nets out, right.
So again, conversely, if youeat a higher carb diet but you
maintain a calorie deficit,right?
So this is a lot of the peopleI work with who want a more
(08:56):
flexible diet, more balanced,where they can enjoy their carbs
, but then we put them into acalorie deficit, guess what?
You're still going to burnglucose, primarily during and
after meals because of the carbs, which suppresses your fat
oxidation, but over a 24-hourperiod, your body's still going
to need to tap into those fatstores once it runs out of
glucose to meet its energy needs, resulting in net fat loss,
(09:19):
just because you don't haveenough energy period Total
energy coming in.
And that happens even thoughyou're not maximizing fat
burning.
Right?
Fat oxidation at every moment.
And this distinction becomesimportant when we look at how
this applies to specificstrategies.
Let's start with low carb diets.
I know I've already hammered ita little bit, but I want to go
(09:40):
one level deep.
And then there's absolutely noquestion that reducing carb
intake shifts your metabolismtoward greater fat oxidation.
We know that.
I'm not going to dispute that.
That's a fact.
Studies consistently showhigher rates of fat oxidation
both at rest and during exercisein people following low-carb
(10:01):
diets, and that is what theRandall Cycle would predict, but
it does not translate to betterfat loss outcomes, because when
calories and protein arecontrolled, the answer is an
emphatic no, there is nodifference.
A meta-analysis by Hall and Guoin 2017 found that low-fat diets
actually produce slightly morefat loss than low-carb diets
(10:22):
when calories were equated.
Now, part of the reason forthat could be because, guess
what?
Your body requires more energyto digest carbs than it does fat
, just like it requires moreenergy to digest protein than
carbs or fat.
So that could be one of thereasons why.
There's probably other reasonsbehind there we're not going to
get into today, likeanti-catabolism, supporting your
(10:42):
training, et cetera.
Similarly, and also your stressand metabolism.
Okay, enough of that.
But similarly, there was astudy.
It was a highly controlledmetabolic ward study.
Everybody locked in one placeand fed a controlled diet.
This is by Hall in 2015,.
Found that a low-fat diet ledto slightly more body fat loss
(11:02):
than a low-carb diet, despitethe low-carb diet showing
increased fat oxidation.
Now, my point isn't to say thatlow-fat's better than low-carb
diet showing increased fatoxidation.
Now, my point isn't to say thatlow-fat's better than low-carb.
It's to say that there's noadvantage to low-carb when it
comes to fat oxidation and fatloss.
Right, yes, you have more fatoxidation, but you're not going
to lose any more fat.
Now it doesn't mean low-carbdiets can't be effective for fat
(11:24):
loss either.
That's what I want to say.
They can be, but not becausethey maximize fat oxidation.
They work for most peoplebecause, number one, you're
going to increase your proteinintake, which is something
everybody needs to do topreserve muscle mass.
Number two, it can improveappetite control in some people.
Some people actually gethungrier on higher carbs.
So having the higher fats andprotein helps with satiety
(11:45):
Totally true phenomenon thathappens.
Number three, you reduce waterretention, and this is just the
appearance of much more rapidprogress early on.
So when somebody says I went onketo and I lost 10 pounds, yeah
, most of that's water weight.
And then, number four, it makesyour diet, I'll say, simpler in
terms of food choices, whichwill have the illusion of making
(12:06):
it easier to adhere, andactually does so for some people
, but for most people itactually makes it harder
long-term because you'reavoiding things that you might
otherwise want to enjoy.
But again, there are exceptions.
There are some people who arelike, yeah, I'm happy as a clam
on my very limited set of foodchoices, that's fine, okay.
The point here is theeffectiveness of a low-carb diet
for fat loss doesn't have to doanything at all with increased
(12:26):
fat oxidation and has everythingto do with energy balance.
Always comes back to that, andthe same principle applies then
to fasted cardio.
I want to talk about fastedcardio.
This is an interesting one,because it is true that
exercising in a fasted state,especially first thing in the
(12:47):
morning before breakfast,results in higher fat oxidation
during the workout.
And if you have not recentlyconsumed carbs to raise insulin,
your body relies even moreheavily on fat.
So if you never eat carbs, ofcourse you're fat adapted.
It's just going to be burning aton of fat.
But this again acute increase,right?
(13:09):
This energy selection processtoward fat burning doesn't
translate to greater fat lossover time, for all the reasons
we've already discussed, butI'll just throw another study at
you by Schoenfeld, a guy I verymuch respect in the space.
This was from 2014,.
Found no difference in fat lossbetween women performing fasted
cardio versus fed cardio whentotal calorie intake was
(13:30):
controlled.
So what matters is total energydeficit if you're going for fat
loss and not whether thatdeficit comes from fat or
carbohydrate oxidation.
Right Now, that's not to sayfasted cardio, has no benefits
at all.
Again, I love nuance andindividualizing here.
The first thing that comes tomind is it's more time efficient
(13:51):
.
For some people.
You get up in the morning andyou go right.
The other thing is it mightimprove your ability to switch
between fuel sources, and thenthis is an interesting one.
Whether that's beneficial inany other way is, I think, still
up for debate, but it does do.
It does potentially do that itmight help you feel better if
you don't like exercising, youknow, with food in the morning
(14:13):
or you don't have time to eatfood, you know there's lots of
like logistical and preferencereasons for this.
And then it might have benefitsfor certain populations with
certain metabolic disorders.
I never disclaim that that's apossibility.
But if you're just trying tolose fat, you know you have to
focus on creating a sustainableenergy deficit, and our last
episode was all about that.
(14:34):
It was all about fat loss.
So go listen to that if youmissed it.
And this happens through yournew training.
New training this is thecombination of nutrition and
training called new training,through your nutrition and
training approach.
Your lifestyle is going to beway more impactful than worrying
about whether you're maximizingfat oxidation, and by way more
I mean like all of it.
(14:54):
In other words, extra fatoxidation from low carb or
faster training, whatever isgoing to make not a lick of
difference in your overall fatloss relative to what the other
lifestyle changes will.
So if acute fat burning, fatoxidation, is not the key to fat
loss, what is Well?
Again, it comes down to basicthermodynamics and energy
balance.
To lose body fat, you have tocreate an energy deficit where
(15:17):
you consume fewer calories thanyou expend.
That is it, and that forcesyour body to mobilize whatever
energy is stored and availableright, preferentially from fat
tissue, to meet its needs.
And again, if you don't haveenough calories coming in and
you're still consuming carbs,it's going to go to carbs and
then it's going to go to fat,but the net effect is the same,
right.
So the key factors here arethen the total calorie intake
(15:40):
versus your expenditure, yourprotein intake, resistance,
training and the ability toadhere to your diet.
Of course, recovery is massiveas well All the things I spoke
about in the last episode, thethree plus three model of fat
loss.
So go for, listen to that, for adeep dive.
And none of these things dependon maximizing fat oxidation at
(16:01):
any given moment.
That is just energy systems.
That is just your body sayinghey, I'm efficient, you need
energy, I need to give youenergy.
Let's see what's on the menutoday.
Is it glucose or is it fat?
It doesn't matter, it's allenergy to your body, right.
And at the end of the day, thedeficit and the energy balance
is what matters.
Which brings me to an importantengineering principle that
applies perfectly here Optimizefor the outcome, not the process
(16:24):
.
Now, you might be confused whenI say this, because I talk all
the time about how important theprocess is.
But if we think of engineeringwhere we focus on the end result
, the product, the system, theservice, the software, we then
reverse, engineer and workbackward to determine the most
efficient way to achieve it.
We don't get caught up inoptimizing I'll say, individual
(16:47):
steps if they don't materiallyaffect the final outcome.
We care about an efficientprocess that gets us to the
outcome right, and then we focuson the process, but we optimize
for the outcome and for fatloss.
This means focusing on thefactors that directly influence
body composition over time, noton momentary metabolic processes
(17:08):
that have little impact on theend result, like I'm not going
to tell you to drink more coffeebecause it might have a slight
thermo thermic boost in yourmetabolism.
That's not an efficient way tooptimize the process.
Think of it like this If you'retrying to save money, what
matters is the differencebetween your income and your
spending right, not whether youpay for a purchase with cash or
credit.
That's effectively what this isGlucose or fat, cash or credit
(17:31):
doesn't matter.
It's all coming from yourenergy budget.
So, with fat loss, what mattersis the difference between your
intake and expenditure, notwhether you're burning fat
versus carbs at a given moment.
And now I want to address onemore aspect of this topic that
causes a lot of confusion, andthat is the difference between
what we measure and what matters.
And this goes back to what Ijust said about optimizing for
(17:54):
the outcome.
When people follow low-carbdiets or they do fasted cardio
or any of these fat-burningtricks, they often point to
indicators of increased fatoxidation as proof that they're
working.
They might mention ketones Look, look at all the ketones in my
urine or blood work.
They might mention a lowerrespiratory quotient RQ during
exercise oh, I'm burning morefat because my RQ is lower.
(18:16):
They might say that they arefat adapted.
Oh, I feel great.
I have steady energy, I don'thave crashes, all my
inflammation has gone away.
You guys seen these posts bypeople.
I went on carnivore andeverything got solved.
Well, these measurements doindeed confirm something they
increase.
They confirm increased fatoxidation.
They might even confirm thatyou have um, eliminated
something that didn't work foryou and then you just never
(18:38):
added, added back the thingsthat do.
That's fine, that's cool.
You start where you're at, butthey don't predict better fat
loss outcomes.
They're measuring individual,independent aspects of the
process rather than the result.
And once you see that theydon't actually produce fat loss
and you reverse engineer it, yousay maybe it's not necessary to
(18:58):
focus on fat oxidation.
In the end, what I actuallyfocus on is measuring and
tracking progress toward the endgoal by optimizing the process.
For that you know my change inbody composition over time, your
, your, your trend, weight, yourmeasurements, your photos, your
, maybe even body fat.
I'm not a big fan of measuringbody fat, but there are ways to
do body fat trends that arehelpful.
Um, has your strength gone upor down?
(19:20):
Have you?
How are your energy levels,your hunger, your well-being?
And yeah, these are outcomes.
And by outcome I don't justmean at the end of the day, did
you lose 20 pounds six monthsfrom now, I mean all the things
that come from your day-to-dayactions in optimizing the
process.
Are you adherent to yourcalorie and protein targets?
That is an outcome of theprocess of being consistent in
(19:42):
hitting your targets.
So, anyway, I can go on, but Ithink it's important to
understand that difference Fatburning, fat loss two different
things.
And this gives you more freedomonce you understand that, with
your nutrition, with yourtraining or with your new
training, just kidding.
And that's what matters, right,what matters is your energy
deficit.
It makes it simple.
It actually makes it reallysimple, and I'm kind of hitting
(20:04):
again on some of the messagesfrom the last episode which,
again, I highly recommendlistening if you didn't.
But when you know that whatmatters is the energy deficit,
it actually frees you in a lotof ways.
It frees you with your mealtiming.
You could eat when yourschedule and preferences match.
You can include carbs I mean,that's the big one that comes to
mind If you enjoy them, if theyfuel your training, if you
(20:25):
tolerate them absolutely.
It informs your training.
You're not going to be choosingmovement or training for fat
burning.
You're going to do somethingthat supports your real goal,
which is strength, muscle,athleticism, whatever, and then
you can find a diet that worksfor you, not based on some
metabolic theory that doesn'tactually produce the results, it
(20:46):
doesn't optimize for the resultand that's much more enjoyable,
in my opinion and they're goingto produce better results
because you're going to sustainthem.
That's what we're going for,right?
The most optimal diet for fatloss is that one that you can
stick with.
I can say that to the cows comehome.
Some people won't accept it.
They want to cut their foods.
They want to claim that fatadapted makes them superior in
some way for fat burning, and itdoesn't right.
(21:07):
Energy balance is where it's at.
All the other things areimportant for other reasons for
health, for strength, et cetera.
But today we wanted to talkabout the difference between fat
loss and fat burning, right?
So, to recap, fat oxidationburning fat for fuel and fat
loss, which is reducing storedbody fat, are distinct
physiological processes thatdon't necessarily go hand in
(21:27):
hand.
The RAND cycle look it up ifyou'd like explains why carb
intake suppresses fat oxidation,but it doesn't prevent fat loss
, because it's the energybalance that matters.
Low-carb diets, fasted cardiothey do increase fat oxidation,
but they don't produce any morefat loss and some studies show
they actually produce less.
(21:48):
For successful fat loss, you'regoing to focus on the factors
that influence body compositionover time.
That's what's important for fatloss.
Go listen to my last episode,the three plus three model of
fat loss, for details.
And then adapting anengineering mindset like we do
here, means optimizing for theoutcomes over days, weeks and
months rather than optimizingfor the process itself.
The bottom line is that I don'twant you to get caught up in
(22:11):
chasing fat burning, becausewhat's going to happen is you're
going to do restrictive, weird,cult-like approaches.
I'm sorry to put it that way,but you are.
You're going to fall into atribe.
That's all about fat burningand you're actually not going to
lose fat.
And I want you to lose fatright.
I want you to lose fat doingsomething that works for you,
that feels great, that's goodfor your body, your preferences,
your lifestyle, that's it Allright.
(22:32):
If you found today's episodehelpful, please take a moment to
leave a five-star review onApple Podcasts and be entered
for a random selection of onewinner each month to receive a
free protein supplement of theirchoice.
And it means a lot to me whenpeople let me know what they
think of the show, and it meansa lot to others when they
understand what they're gettinginto, for better or worse.
(22:54):
Just go to Apple Podcasts onyour Apple device, search for
Wits and Weights, click ratingsand reviews and leave your
feedback.
Takes about one minute, but itmakes a huge difference, so I
really appreciate it.
Until next time, keep usingyour wits lifting those weights
and remember, when it comes tofat loss, it is not about
burning fat in the moment.
It's about creating theconditions for your body to lose
fat over time.
(23:15):
This is Philip Pape and you'vebeen listening to Wits and
Weights.
I will talk to you next time.
Bye.
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