How To Burn Fat Instead of Carbs: Quick Summary
An in-depth article explaining the difference between burning glycogen vs. fat, factors that influence which fuel your body uses, and whether burning fat instead of glycogen is actually better for weight loss.
Who is this article for?
• People trying to lose weight or optimize fat loss
• Athletes curious about energy systems and workout fueling
• Anyone considering keto or other diet strategies to burn fat for fuel
Key points to know:
Fuel basics:
Glycogen vs. Fat use:
High-intensity training = mostly glycogen.
Longer, lower-intensity cardio = mostly fat.
Heart rate below “Maximum Aerobic Function” (180 – age) generally indicates when fat is being utilized as the primary fuel source.
How to burn more fat instead of glycogen:
Exercise style & intensity: Low-intensity cardio encourages fat burning, while resistance training uses more glycogen.
Dietary approach: Eating fewer carbs reduces glycogen storage, nudging the body toward fat oxidation. A ketogenic diet can accelerate this shift by entering ketosis.
Keto diet insights:
Ratios: ~70–80% fat, 10–20% protein, 5–10% carbs.
• May help moderate blood sugar and insulin resistance.
• Often causes quick water and glycogen weight loss early on, not necessarily body fat.
• Long-term sustainability is difficult, and results depend on maintaining a calorie deficit.
Bottom line for fat loss:
Burning fat instead of glycogen doesn’t guarantee faster fat loss.
True fat loss still depends on:
• Maintaining a calorie deficit
• Eating enough protein for muscle preservation
• Exercising consistently
Every single one of us needs energy in order to live. That might sound like common sense, but it’s something that people forget way too often!
This energy comes from the food that we eat. Even more specifically, this energy comes from the calories in our food, which are made up of macronutrients.
These macronutrients consist of protein, carbohydrates, and fats.
So, which of the macronutrients do our bodies rely on for fuel? Primarily carbs and fats.
Now, if you are somebody who is looking to burn fat, then there are some ways that you can make sure that’s happening.
If you came here to learn about the benefits that come along with burning fat instead of glycogen, the difference between fat and glycogen, and how to burn fat instead of glycogen…
Then you came to the right place! Follow along for more about how to burn fat instead of glycogen.
Fuel and Energy
Like we talked about above, protein, carbohydrates, and fats are what make up the calories that give us energy. This energy is then used in our daily activities and bodily functions.
Carbs and fats are our main sources of energy.
You might be wondering how each macronutrient is used in your body.
Well, when you eat carbohydrates, your body breaks them down into glucose. This glucose is immediately used by your cells. Then, this glucose is stored in your liver and muscles as glycogen to be used later on.
Fats, on the other hand, tend to get turned into fatty acids. These fatty acids get oxidized and used as fuel for your body.
Protein CAN be used as a fuel source, but not unless it has to be. Protein is made up of amino acids. Amino acids are the building blocks of every single tissue in your body.
For this reason, protein is normally reserved for building and repairing tissue.
Because of this, your body prefers glucose and fatty acids to be used as energy.
Glycogen vs Fat: What Does Your Body Like To Use For Energy?
With all of this talk about carbs and fats, you’re probably wondering what your body prefers to use…
Before we dive into that, it’s important to point out that our bodies can adapt. We adapt based on what’s available, activity level, and it does a great job at reading and reacting to what we need.
Now, carbohydrates are your body’s preferred source of energy. This is because glucose is the most readily available form of energy in your body. This is what your body tends to use first, especially in high-intensity workouts.
If there is any glucose left over, it is stored in your muscles or liver as glycogen. If there is any left over after that, it can be stored as body fat.
On the other hand, fats are broken down and used as energy in a slower, more sustained way.
The body will shift and use fats for fuel when you are exercising for an extended period of time. After being used in your body for energy, excess fat can be stored as body fat too.
Burning Glycogen vs Burning Fat
One of the major factors that determines what your body is burning for fuel is the intensity of what you do.
The higher the intensity of your workouts, the more likely you are to use glycogen first.
Workouts can be broken down into two categories to simplify this: resistance training and cardio training.
There's a very simple way to determine whether you burn glycogen or body fat for these categories.
How To Burn Fat Instead of Glycogen
There are a number of factors to consider when thinking about how to burn fat instead of glycogen.
I know I’ve briefly mentioned some above, but we’ll take a closer look here.
So let’s dive into three of the main ways that you can make sure that you are burning fat instead of glycogen. Check out our men's fat burners and women's fat burners specifically formulated to support your fat-burning efforts.
Exercise Intensity & Style
Remember when I said the type of exercise you do and the intensity are factors to consider? That’s especially important when designing a fat-burning workout routine, since different training styles tap into different energy systems.
Well, when it comes to resistance training, your body mostly uses glycogen for fuel.
This includes all kinds of resistance training, too. Bodyweight workouts, traditional lifting, and CrossFit are just a few examples.
Now, when it comes to cardio-based workouts, the energy your body uses depends ... and it depends on the intensity of your workout.
Cardio workouts can be anything from walking to running, biking, and rollerblading. Really, you have a lot of options for workouts in this category, too.
In these workouts, the fuel your body uses can generally be determined by your heart rate. If your heart rate goes above your maximum aerobic threshold, you will likely be using glycogen for fuel.
The formula looks like this: Maximum Aerobic Function Equation = 180 - AGE (1).
For example, if somebody who is 30 years old gets their heart rate above 150 beats per minute (BPM), then they are likely using glycogen for fuel. Anything less than 150 BPM, their body would likely be using fats for fuel.
So, one way you can burn fat instead of glycogen is through your workouts. Doing more low-intensity cardio could certainly be a way to do this. Some athletes use glycogen supplements to help maintain their glycogen stores and sustain performance during extended or high-intensity sessions.
Gender Differences
You’ll hear a lot of different things about how men and women burn fat. Heck, you've probably even met people who blame their gender or genetics for a cruddy metabolism.
So, is there truth to this? What does the research say?
Well, it says there isn't a huge difference at all. With that being said, there is a difference.
Believe it or not, there is slightly increased fat oxidation in women (3).
At the end of the day, though, this will still have very little impact on overall weight loss. Plus, it really has nothing to do with burning fat instead of glycogen.
Dietary Factors
Another factor that can help your body burn fat instead of glycogen is your diet. In fact, it's so simple that a lot of people overlook it.
If you eat fewer carbs, then your body will have less stored glycogen. Well, if your body doesn't have much glycogen, then it can't use it. This could help influence your body to burn fat instead of glycogen (2).
Let's take this a step further, though, because cutting carbs isn't necessarily what's going to make your body burn fat. If your goal is to convert your body to burning fat instead of glycogen through your diet ... This is possible through a ketogenic diet.
What Is a Ketogenic Diet?
A ketogenic diet is what a lot of people refer to as "keto". It's where you prioritize low carbohydrate intake, moderate protein intake, and a high fat intake (4).
It's an approach that many people will try to lose weight.
How does keto work? With the proper balance of these nutrients, your body will begin to draw its energy from dietary fats and body fat. Once it does this, your body will start to produce ketone bodies.
Ketone bodies are a source of fuel that our body already uses. However, with a keto diet, your blood ketone levels should increase. This can be an indication that your body has entered a state of ketosis, where it is utilizing more fat for energy as opposed to glycogen.
The problem is, achieving ketosis can be extremely difficult. I'll get into why this is soon. First, let's discuss some of the potential benefits of following a keto diet.
Benefits of Keto
There are some benefits that can come along with following the keto diet.
I also understand a lot of people can be very opinionated on this topic ... So, I'll keep it strictly to the science.
Keto Can Lead To More Weight Loss … At First!
You’ll hear that cutting carbs can be a great way to lose weight. Well, this can be true! The problem is, the weight loss you experience at first probably won't be fat.
You see, when you limit carb intake, you tend to draw less water to your muscles. This is where a majority of the initial weight loss comes from (5).
Whether you do keto or not, weight loss and fat loss still rely on a calorie deficit. That means you still have to consume fewer calories than you burn.
So, even though your body will be burning fat instead of glycogen, that doesn't mean you'll lose more body fat.
This initial weight loss on a ketogenic diet could convince you otherwise. Just know, this weight loss is not from body fat.
May Moderate Blood Sugar Levels & Improve Insulin Resistance
The ketogenic diet could be beneficial for people with irregular blood sugar levels and insulin resistance (6).
When you eat fewer carbs, you are literally lowering the sugar levels in your blood as well as insulin levels. This also helps explain how keto could be helpful for insulin resistance.
On top of that, ketone bodies could help influence insulin signaling directly (9).
How To Calculate Macros For Keto
Where most people fall short with keto is with the diet itself. Unfortunately, you can't just cut out carbs and magically start burning fat instead of glycogen.
To enter a state of ketosis and maintain it, you have to eat a very specific ratio of carbs, fats, and protein. In other words, you have to track your food intake and stay very disciplined.
Here is what's generally recommended for keto:
• Protein: 10-20% total daily calorie intake
• Carbohydrates: 5-10% total daily calorie intake
• Fat: 70-80% total daily calorie intake
As an example, someone following a 2000-calorie plan would have a breakdown that looks like this:
• Protein: 200-400 calories (50-100 grams)
• Carbohydrates: 50-100 calories (12-25 grams)
• Fat: 1400-1600 calories (156-178 grams)
While some people may be able to have slightly more protein, it will come down to trial and error. However, this will be very close to where you need to be if you plan to follow a keto diet.
I guess the question is … is it worth it? Is keto the best approach for burning more body fat?
Is Keto The Best Way To Lose Fat?
Some will argue that keto is the best way to lose fat, others will argue it isn't.
Personally, I don't have anything against keto. The truth is, it can be just as effective as any other diet.
At the same time, though, I've found that it can be next to impossible to maintain long-term. You have to be extremely disciplined with the ratios you consume, the foods you eat, and the supplements you take.
Without carbohydrates, your body can miss out on a lot of the essential vitamins, minerals, and nutrients it needs to function at its best. For this reason, I typically recommend keto dieters supplement their essential nutrients and fiber.
On top of that, there are only so many healthy fat sources you can have. A lot of fat I see people eat on keto is not necessarily the healthiest.
At the end of the day, you won't lose any more body fat on keto than you will on any other diet. Yes, this is even though your body could be burning fat instead of glycogen. That's because weight loss comes down to the calories you consume vs the calories you burn.
So, is keto the best way for you to lose fat? I'd say no. The best way for you to lose fat will likely be the approach you can maintain long-term.
Burning Fat Instead of Glycogen: Is It Better For Weight Loss?
Thinking that burning fat instead of glycogen is best for fat loss is not faulty thinking. However, the truth is, it won't actually make your body lose fat any more quickly.
If you're looking to lose body fat, it's all about finding a plan you can stick with consistently.
For me, and most of the people I work with, we focus on a healthy balance. There are only three main factors I have people prioritize when it comes to weight loss:
1. Calorie Intake
2. Protein Intake
3. Exercise
The calorie deficit will help you lose weight.
The protein will help you improve your composition.
The training will be a necessary component to earning the results you're after.
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References:
(1) Maffetone P, Laursen PB. Maximum Aerobic Function: Clinical Relevance, Physiological Underpinnings, and Practical Application. Front Physiol. 2020;11:296.
(2) Zouhal H, et al. Exercise Training and Fasting: Current Insights. Open Access J Sports Med. 2020;11:1-28.
(3) Chenevière X, et al. Gender differences in whole-body fat oxidation kinetics during exercise. Appl Physiol Nutr Metab. 2011;36(1):88-95.