Fat Oxidation vs. Fat Loss Explained

Philip Pape 0:01

If you've ever been confused about why you can burn fat during a workout but not actually lose body fat , or why low-carb diets promise to keep you fat-adapted in fat-burning mode , yet sometimes fail to deliver results , this episode is for you . Today , we're uncovering the difference between fat oxidation and actual net fat loss that almost everyone misunderstands . You'll learn how the Randall Cycle affects your metabolism , why fasted cardio might not be the magic bullet you think it is , and what really determines whether you lose fat , regardless of what fuel your body is burning in the moment . Welcome to Wits and Weights , the show that helps you build a strong , healthy physique using evidence , engineering and efficiency . I'm your host , philip Pape , certified nutrition coach , and today we're looking at one of the most misunderstood concepts in fitness , and that is the difference between fat burning , or the technical term oxidation , and fat loss , which is literally losing fat from your body generally by losing weight and holding on to muscle . This confusion is often led to questions that come up on a daily basis , especially when I write or do an episode about carbs or low-carb diets , where people say , well , I'm fat-adapted or I burn more fat because I'm low-carb , and it's a complete misunderstanding of what's actually going on , and so people chase down ineffective diets , potentially restrictive diets that are miserable . They waste their workouts by not training the right way and then they get frustrated . They can't figure out why they're not seeing results despite doing the things you're supposed to do . To quote unquote burn fat . The reality is that fat burning and fat loss are two completely different physiological processes . It's unfortunate that they sound very similar , but if we can understand the distinction , it will help you improve your body composition because you'll be informed on whether you're putting your energy in the right place . So by the end of the episode , my goal is to help understand why things like low-carb diets , fasted cardio , other popular quote-unquote fat-burning strategies might not be working as promised . They might have some misdirection in there , and what you should focus on instead if you really want the results .

Philip Pape 2:27

Before we dive in , I do have a quick favor to ask If you enjoy today's episode . Take a moment to leave a five-star review on Apple Podcasts . Each month , I'm randomly selecting one reviewer and they're going to receive a free protein supplement of their choice . This is my way of saying thank you for supporting the show , and the reviews help other people discover this show , why people like it and how it might help them to escape the sea of confusion , of misinformation that's out there . So again , go to Apple Podcasts , submit a five-star review , do it on your iPhone or Apple device , and if you don't have that device or don't use an Apple podcast , feel free to throw in a rating on Spotify , or just shoot me a message and say , hey , show's great , thanks for doing it , and that'll make my day All right .

Philip Pape 3:14

So let's get into the topic and start by defining what we're talking about . The confusion between fat oxidation and fat loss is , honestly , at the heart . It is at the root of so many popular strategies today that are misguided , oftentimes because of this very thing . So what is the difference ? Fat oxidation when we say fat burning , right , that is a metabolic process where your body breaks down fat molecules to produce energy , and that's what typically mean when they talk about burning fat during exercise or following a diet or in any situation , fasted training , etc . It's essentially the use of fat as 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 fat loss . See , fat loss actually is the reduction of stored body fat over time , and this is what most of us are actually trying to 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 fat stored 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 , more athletic all of the things . So I think what most people miss is that these two processes burning fat for fuel in the moment versus reducing stored body fat over time don't always go hand in hand . In fact , oftentimes they don't go hand in hand . They're different , independent things going on .

Understanding The Randall Cycle

Philip Pape 4:41

You can oxidize plenty of fat during your workouts . Going on , you can oxidize plenty of fat during your workouts , but not lose body fat from your body . Conversely , you can be primarily burning carbohydrates during exercise , yet still lose significant amounts of body fat over time , and so this disconnect leads to confusion , especially around low carb diets , keto carnivore , fasted training all sorts of strategies you know , fat burning workouts that promise to maximize fat burning . So that's why I'm creating this episode .

Philip Pape 5:09

Now let's take a look at the physiology first . I think that's a great place to start and there's something called the Randall cycle . Now I heard about this a long time ago . I kind of forgot about it , specifically by name , until a YouTube commenter mentioned it and they said hey , if this is all true , if low carb diets might not be beneficial for a lot of people , um , why , what about the cycle ? Why , why ? Why isn't that the reason low carb diets would be so beneficial ?

Philip Pape 5:35

So the Randall cycle it's also known as the glucose fatty acid cycle . It was first described by Philip Randall in the sixties 1963 . And it describes the relationship between carbohydrate and fat metabolism in our bodies . So essentially it explains that when your body has both glucose and fatty acids available right , glucose from carbs , fatty acids from fats available as fuel they compete with each other . So when glucose levels are high , your body's going to preferentially burn glucose and suppress fat oxidation right , so it's burning glucose because it's there instead of fat . When glucose levels are low , your body's going to shift to burning more fat .

Philip Pape 6:15

Now , before I move on , notice what this means . This means when someone says glucose is the body's preferred energy source . That is a true statement , meaning it will burn that if it's available first , then it will burn fat . But of course , if you deprive yourself of carbohydrates , it has no choice but to burn fat . So let's continue . So this is kind of a reciprocal in a way , but it is a little bit asymmetric . Your body's designed to use whatever fuel's most readily available , but it's going to go for glucose first if it's available . That's why it's slightly asymmetric . But it's going to preserve whatever's in shorter supply effectively for when it might be needed later . And that's why the low carb advocates and the fasted cardio enthusiasts where they come in , because they on one hand correctly note that high insulin levels from carbohydrate consumption suppresses fat oxidation , but then they conclude that to lose body fat you should minimize carbohydrate intake to stay in that fat burning mode as much as possible .

Philip Pape 7:11

But here's the flaw Very important what matters for fat loss isn't the fuel you're burning at the moment , but your overall energy balance over time . That's the key distinction here . So guess what's happening on a low-carb diet ? You're eating more fats . In other words , you are taking in the same amount of energy . You're just burning a different type of energy because you have more of it . That's all you're doing , right ? Whereas a person with moderate to high carbs is eating less fat . So they're burning more carbs . It all nets out to the same thing in terms of energy balance , and the Randall cycle simply addresses the fuel selection . You know you have a fuel selection dial . Am I going to burn glucose or am I going to burn fat ? It's not the chronic change in your fat mass on your body .

Philip Pape 7:57

So if I gave you a concrete example , let's say you're eating a low carb , high fat diet , right , keto , carnivore , we know them . Your insulin levels are gonna be relatively low and you'll be primarily oxidizing fat for fuel throughout the day . And if you're on keto , you might be to the point of past ketosis where you are what people call fat-adapted , where you just that's always what you're doing . So that's great . You're burning fat , right , you're burning fat right . But if your total calorie intake exceeds your expenditure , you're still going to gain body fat , even though you're primarily using fat as fuel , because the dietary fat you consume but don't immediately burn is going to get stored . So you're just eating more fat and that all that extra fat is now going to get stored , whereas with the other guy who's eating a balanced diet , the extra carbs are going to get or the fat's gonna get stored while you burn the carbs , it doesn't matter . The energy nets out , right . So again , conversely , if you eat a higher carb diet but you maintain a calorie deficit , right ? So this is a lot of the people I work with who want a more flexible diet , more balanced , where they can enjoy their carbs , but then we put them into a calorie deficit , guess what ? You're still going to burn glucose , primarily during and after meals because of the carbs , which suppresses your fat oxidation , but over a 24-hour period , your body's still going to need to tap into those fat stores once it runs out of glucose to meet its energy needs , resulting in net fat loss , just because you don't have enough energy period Total energy coming in . And that happens even though you're not maximizing fat burning . Right ? Fat oxidation at every moment . And this distinction becomes important when we look at how this applies to specific strategies

Low-Carb Diets & Fat Loss Truth

Philip Pape 9:35

.

Philip Pape 9:36

Let's start with low carb diets . I know I've already hammered it a little bit , but I want to go one level deep . And then there's absolutely no question that reducing carb intake shifts your metabolism toward greater fat oxidation . We know that . I'm not going to dispute that . That's a fact . Studies consistently show higher rates of fat oxidation both at rest and during exercise in people following low-carb diets , and that is what the Randall Cycle would predict , but it does not translate to better fat loss outcomes , because when calories and protein are controlled , the answer is an emphatic no , there is no difference .

Philip Pape 10:14

A meta-analysis by Hall and Guo in 2017 found that low-fat diets actually produce slightly more fat loss than low-carb diets when calories were equated . Now , part of the reason for that could be because , guess what ? Your body requires more energy to digest carbs than it does fat , just like it requires more energy to digest protein than carbs or fat . So that could be one of the reasons why . There's probably other reasons behind there we're not going to get into today , like anti-catabolism , supporting your training , et cetera . Similarly , and also your stress and metabolism . Okay , enough of that . But similarly , there was a study . It was a highly controlled metabolic ward study . Everybody locked in one place and fed a controlled diet . This is by Hall in 2015, . Found that a low-fat diet led to slightly more body fat loss than a low-carb diet , despite the low-carb diet showing increased fat oxidation .

Philip Pape 11:06

Now , my point isn't to say that low-fat's better than low-carb diet showing increased fat oxidation . Now , my point isn't to say that low-fat's better than low-carb . It's to say that there's no advantage to low-carb when it comes to fat oxidation and fat loss . Right , yes , you have more fat oxidation , but you're not going to lose any more fat . Now it doesn't mean low-carb diets can't be effective for fat loss either . That's what I want to say . They can be , but not because they maximize fat oxidation .

Philip Pape 11:29

They work for most people because , number one , you're going to increase your protein intake , which is something everybody needs to do to preserve muscle mass . Number two , it can improve appetite control in some people . Some people actually get hungrier on higher carbs . So having the higher fats and protein helps with satiety Totally true phenomenon that happens . Number three , you reduce water retention , and this is just the appearance of much more rapid progress early on . So when somebody says I went on keto and I lost 10 pounds , yeah , most of that's water weight . And then , number four , it makes your diet , I'll say , simpler in terms of food choices , which will have the illusion of making it easier to adhere , and actually does so for some people , but for most people it actually makes it harder long-term because you're avoiding things that you might otherwise want to enjoy . But again , there are exceptions . There are some people who are like , yeah , I'm happy as a clam on my very limited set of food choices , that's fine , okay .

Philip Pape 12:20

The point here is the effectiveness of a low-carb diet for fat loss doesn't have to do anything at all with increased fat oxidation and has everything to do with energy balance . Always comes back to that , and the same principle applies then to fasted cardio . I want to talk about fasted cardio . This is

Fasted Cardio Myths Debunked

Philip Pape 12:40

an interesting one , because it is true that exercising in a fasted state , especially first thing in the morning before breakfast , results in higher fat oxidation during the workout . And if you have not recently consumed carbs to raise insulin , your body relies even more heavily on fat . So if you never eat carbs , of course you're fat adapted . It's just going to be burning a ton of fat . But this again acute increase , right ? This energy selection process toward fat burning doesn't translate to greater fat loss over time , for all the reasons we've already discussed , but I'll just throw another study at you by Schoenfeld , a guy I very much respect in the space . This was from 2014, . Found no difference in fat loss between women performing fasted cardio versus fed cardio when total calorie intake was controlled . So what matters is total energy deficit if you're going for fat loss and not whether that deficit comes from fat or carbohydrate oxidation .

Philip Pape 13:42

Right Now , that's not to say fasted cardio , has no benefits at all . Again , I love nuance and individualizing here . The first thing that comes to mind is it's more time efficient . For some people . You get up in the morning and you go right . The other thing is it might improve your ability to switch between fuel sources , and then this is an interesting one . Whether that's beneficial in any other way is , I think , still up for debate , but it does do . It does potentially do that it might help you feel better if you don't like exercising , you know , with food in the morning or you don't have time to eat food , you know there's lots of like logistical and preference reasons for this . And then it might have benefits for certain populations with certain metabolic disorders . I never disclaim that that's a possibility .

Philip Pape 14:26

But if you're just trying to lose fat , you know you have to focus on creating a sustainable energy deficit , and our last episode was all about that . It was all about fat loss . So go listen to that if you missed it . And this happens through your new training . New training this is the combination of nutrition and training called new training , through your nutrition and training approach . Your lifestyle is going to be way more impactful than worrying about whether you're maximizing fat oxidation , and by way more I mean like all of it . In other words , extra fat oxidation from low carb or faster training , whatever is going to make not a lick of difference in your overall fat loss relative to what the other lifestyle changes will .

Philip Pape 15:04

So if acute fat burning , fat oxidation , is not the key to fat loss , what is Well ? Again , it comes down to basic thermodynamics and energy balance . To lose body fat , you have to create an energy deficit where you consume fewer calories than you expend . That is it , and that forces your body to mobilize whatever energy is stored and available right , preferentially from fat tissue , to meet its needs . And again , if you don't have enough 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 are then the total calorie intake versus your expenditure , your protein intake , resistance , training and the ability to adhere to your diet . Of course , recovery is massive as well All the things I spoke about in the last episode , the three plus three model of fat loss .

Philip Pape 15:52

So go for , listen to that , for a deep dive . And none of these things depend on maximizing fat oxidation at any given moment . That is just energy systems . That is just your body saying hey , I'm efficient , you need energy , I need to give you energy . Let's see what's on the menu today . Is it glucose or is it fat ? It doesn't matter , it's all energy to your body , right . And at the

Optimize For Outcomes, Not Process

Philip Pape 16:13

end of the day , the deficit and the energy balance is what matters . Which brings me to an important engineering principle that applies perfectly here Optimize for the outcome , not the process .

Philip Pape 16:25

Now , you might be confused when I say this , because I talk all the time about how important the process is . But if we think of engineering where we focus on the end result , the product , the system , the service , the software , we then reverse , engineer and work backward to determine the most efficient way to achieve it . We don't get caught up in optimizing I'll say , individual steps if they don't materially affect the final outcome . We care about an efficient process that gets us to the outcome right , and then we focus on the process , but we optimize for the outcome and for fat loss . This means focusing on the factors that directly influence body composition over time , not on momentary metabolic processes that have little impact on the end result , like I'm not going to tell you to drink more coffee because it might have a slight thermo thermic boost in your metabolism . That's not an efficient way to optimize the process . Think of it like this If you're trying to save money , what matters is the difference between your income and your spending right , not whether you pay for a purchase with cash or credit . That's effectively what this is Glucose or fat , cash or credit doesn't matter . It's all coming from your energy budget . So , with fat loss , what matters is the difference between your intake and expenditure , not whether you're burning fat versus carbs at a given moment . And now I want to address one more aspect of this topic that causes a lot of confusion , and that is the difference between what we measure and what matters . And this goes back to what I just said about optimizing for the outcome .

Philip Pape 17:55

When people follow low-carb diets or they do fasted cardio or any of these fat-burning tricks , they often point to indicators of increased fat oxidation 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 lower respiratory quotient RQ during exercise oh , I'm burning more fat because my RQ is lower . They might say that they are fat adapted . Oh , I feel great . I have steady energy , I don't have crashes , all my inflammation has gone away . You guys seen these posts by people . I went on carnivore and everything got solved . Well , these measurements do indeed confirm something they increase . They confirm increased fat oxidation . They might even confirm that you have um , eliminated something that didn't work for you and then you just never added , added back the things that do . That's fine , that's cool .

Philip Pape 18:42

You start where you're at , but they 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 they don't actually produce fat loss and you reverse engineer it , you say maybe it's not necessary to focus on fat oxidation . In the end , what I actually focus on is measuring and tracking progress toward the end goal by optimizing the process . For that you know my change in body composition over time , your , your , your trend , weight , your measurements , your photos , your , maybe even body fat .

Philip Pape 19:14

I'm not a big fan of measuring body fat , but there are ways to do body fat trends that are helpful . Um , has your strength gone up or down ? Have you ? How are your energy levels , your hunger , your well-being ? And yeah , these are outcomes . And

Final Thoughts & Energy Balance Importance

Philip Pape 19:27

by outcome I don't just mean at the end of the day , did you lose 20 pounds six months from now , I mean all the things that come from your day-to-day actions in optimizing the process . Are you adherent to your calorie and protein targets ? That is an outcome of the process of being consistent in hitting your targets . So , anyway , I can go on , but I think it's important to understand that difference Fat burning , fat loss two different things .

Philip Pape 19:51

And this gives you more freedom once you understand that , with your nutrition , with your training 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 really simple , and I'm kind of hitting again on some of the messages from the last episode which , again , I highly recommend listening if you didn't . But when you know that what matters is the energy deficit , it actually frees you in a lot of ways . It frees you with your meal timing . You could eat when your schedule and preferences match . You can include carbs I mean , that's the big one that comes to mind If you enjoy them , if they fuel your training , if you tolerate them absolutely . It informs your training .

Philip Pape 20:34

You're not going to be choosing movement or training for fat burning . You're going to do something that supports your real goal , which is strength , muscle , athleticism , whatever , and then you can find a diet that works for you , not based on some metabolic theory that doesn't actually produce the results , it doesn't optimize for the result and that's much more enjoyable , in my opinion and they're going to produce better results because you're going to sustain them . That's what we're going for , right ? The most optimal diet for fat loss is that one that you can stick with . I can say that to the cows come home .

Philip Pape 20:59

Some people won't accept it . They want to cut their foods . They want to claim that fat adapted makes them superior in some way for fat burning , and it doesn't right . Energy balance is where it's at . All the other things are important for other reasons for health , for strength , et cetera . But today we wanted to talk about the difference between fat loss and fat burning , right ? So , to recap , fat oxidation burning fat for fuel and fat loss , which is reducing stored body fat , are distinct physiological processes that don't necessarily go hand in hand . The RAND cycle look it up if you'd like explains why carb intake suppresses fat oxidation , but it doesn't prevent fat loss , because it's the energy balance that matters . Low-carb diets , fasted cardio they do increase fat oxidation , but they don't produce any more fat loss and some studies show they actually produce less .

Philip Pape 21:48

For successful fat loss , you're going to focus on the factors that influence body composition over time . That's what's important for fat loss . Go listen to my last episode , the three plus three model of fat loss , for details . And then adapting an engineering mindset like we do here , means optimizing for the outcomes over days , weeks and months rather than optimizing for the process itself . The bottom line is that I don't want you to get caught up in chasing fat burning , because what'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 a tribe . That's all about fat burning and you're actually not going to lose fat . And I want you to lose fat right . I want you to lose fat doing something that works for you , that feels great , that's good for your body , your preferences , your lifestyle , that's it All right .

Philip Pape 22:32

If you found today's episode helpful , please take a moment to leave a five-star review on Apple Podcasts and be entered for a random selection of one winner each month to receive a free protein supplement of their choice . And it means a lot to me when people let me know what they think of the show , and it means a lot to others when they understand what they're getting

Episode Wrap-Up

Philip Pape 22:53

into , for better or worse . Just go to Apple Podcasts on your Apple device , search for Wits and Weights , click ratings and reviews and leave your feedback . Takes about one minute , but it makes a huge difference , so I really appreciate it . Until next time , keep using your wits lifting those weights and remember , when it comes to fat loss , it is not about burning fat in the moment . It's about creating the conditions for your body to lose fat over time . This is Philip Pape and you've been listening to Wits and Weights . I will talk to you next time . Bye .