To get into ketosis you need to go through a period of adaptation. To do that you have to either fast or restrict your carbohydrate intake to a bare minimum. For faster results, you can also exercise. But there are different ways how to workout on keto.

Our body can use various fuel sources.

  • The most preferred one is glucose, which is basically carbohydrate or sugar molecules, that gets absorbed very quickly.
  • Next, to that, there are free fatty acids that can either be derived from dietary fat intake or our own body fat.
  • Lastly, the third ones are called ketone bodies that are like “superfuel”, reigning supreme over the other two.

By default, the body uses glucose as its main fuel. This is reinforced even more by the high amounts of them in our diet. To create energy sugar enters the Krebs cycle during the process called glycolysis. What comes out is pyruvate that gets converted to ATP.

The body can store about 2000 calories of glycogen (15g are circulating the bloodstream, 150g are stored in the liver and 300-500g in muscle cells). Liver glycogen stores can be depleted already after an overnight fast. It’s our first fuel tank. To release glucose from muscle cells we need a lot more. This supply is scarce and used only when there’s no other way. When we would have to run from a lion or sprint after the bus.

Glycogen Depletion is Important to Know for Knowing How to Workout on Keto Glycogen Depletion is Important to Know for Knowing How to Workout on Keto

Muscle glycogen stores get tapped into only during very intense and glycolytic activities. When in an anaerobic mode we’re utilizing solely glucose for fuel to produce ATP with no oxygen.

Free fatty acids, on the other hand, are almost infinite in terms of caloric storage. We can deposit as many triglycerides in our adipose tissue as we can possibly consume.

Despite glucose being the body’s primary fuel source, most of the time we’re using fat for fuel. During activities with lower intensities, we’re being aerobic, which means that we have access to oxygen and can breathe normally. In this state, we’re capable of maintaining movement for long periods of time without running into a fuel crisis.

Burning fatty acids in the Krebs cycle leads to the creation of a ketone body acetoacetate, which then gets converted further into beta-hydroxybutyrate and acetone. They can produce up to 25% more energy than pyruvate. However, that’s in terms of quantity, not intensity.

Everyone can burn fatty acids and create ketones. The key factor for establishing ketosis is glycogen depletion – you need to empty your liver glycogen stores, which takes about 16-20 hours. In fact, you’re in mild ketosis already after an overnight fast.

You can also use fat for fuel while being aerobic. It doesn’t mean that you’re doing it as your primary source. You won’t be able to utilize ketones for their true potential unless you’ve adapted to do it.

After the initial adaptation phase, your body’s physiology and biochemistry will be altered and you’ll be able to become a fat burning beast. How to train in ketosis depends on your level of fat adaptation.

When it comes to choosing between which energy system benefits more from ketones, then the answer is obviously: the aerobic one.

Image result for fuel use during exercise

How to workout on keto graph

At lower intensities, the body will happily use fatty acids or ketones for fuel and will spare its muscle glycogen for emergencies. That energy will be derived either from ingested dietary fat or, once we’ve run out of consumed calories, our own adipose tissue.

In the case of sugar burning, you’ll be able to do the same but only to a certain extent. After you’ve run out of immediate fuel, you’re going to burn fat. But because you’re mainly running on glucose, you’ll also begin to break down your own tissue through gluconeogenesis. This process breaks down protein from your muscle cells and organs to convert it into sugar. It’s a very inefficient way of producing energy and happens because the body doesn’t know how to utilize ketones.

When in deep ketosis, you reduce muscle catabolism to a bare minimum because of being able to find an efficient solution to the energy crisis.

Unless you’re fully keto-adapted, your anaerobic performance will suffer slightly. If the body is still yearning for glucose, then you won’t be able to use ketones at higher intensities. At least as much as your mind would like to.

However, it doesn’t mean that you can’t train without oxygen or sugar.

High-intensity training, such as HIIT cycles, are anaerobic by nature and span the creatine-phosphate system. Past that 90% of your maximum, you’re actually using glycogen quite inefficiently as well. It’s just that you’ll be able to produce explosive ATP faster with glucose.

Image result for creatine phosphate system

After you’ve gone through the shift, you’ll be able to spare your glycogen and can actually perform at your maximum with ketones as effectively as you would when using glucose.

The popular belief is that you need carbohydrates to store glucose. This seems obvious because our muscle cells and liver can store glycogen, which is sugar. If you want to replenish your fuel, then eat carbs, right?

However, it’s not necessary to eat carbs to refill our glycogen stores. Glycerol, which is found in triglycerides, can be turned into glycogen through the same process of gluconeogenesis. Consumption of foods with amino acids and low carb vegetables also contributes to this. After some time, you will be able to store glycogen even on a ketogenic diet.

The only benefit to eating easily absorbable carbohydrates would be that they get the job done faster. Unless you’re training for the Olympics you don’t need to “carb load.”

Our approach would have to depend on our level of adaptation. At first, the body is still quite glucose dominant and prefers the glycolytic pathway. To do that, it will either cause sugar cravings or cause muscle catabolism during exercise.

Every time you have excess glucose circulating your bloodstream, you’re impeding keto-adaptation. As glucose goes up, ketones go down, because they’re conflicting fuel sources.

That’s why it’s best to stay aerobic for the majority of the time, at least during the initial phase. A good rule of thumb is that when you’re breathing hard, you’re being more anaerobic. IF you’re able to breathe easily through your nose, then you’re aerobic.

It’s not needed to empty your muscle glycogen to get into ketosis as ketone bodies are mediated by the liver. Lifting weights and doing high-intensity resistance training during the adaptation phase can be counter-productive because your performance may be hindered. Nevertheless, exercise, in general, will help you to get into ketosis faster.

Image result for heart rate zones

You should lay your ego aside for the time being and stick to lower intensities. This period is a great opportunity to focus more on endurance, mobility and less on resistance training. Keto weight training is possible even during adaptation. To teach your body how to use fat for fuel faster, you’ll have to be mainly aerobic. At least for the majority of the time.

Once you’ve gone through about 2-3 weeks of eating low carb, you’ll probably be in ketosis. Your body will have gone through the alteration of its own biology.

Now, you’ve adapted to using fat and ketones for fuel. The longer you continue, the more efficient you’ll become. Your energy levels will improve and so does your training. You’ll see how to workout on keto and it feels quite good.

If you experienced an initial drop in performance. It happened because you underwent a small energy crisis which you have now overcome.

During aerobic exercise, you’re using solely ketones for fuel. This will also transition over to the anaerobic system. You’ll be able to perform at 90% of your maximum equally as good as on glucose after your body adapts to ketones.

Your muscle glycogen stores get replenished despite the non-existing presence of lots of carbohydrates. Because of your ability to use your own body fat for fuel extremely efficiently, you won’t tap into them that often either. When you do, they can be restored after some time even on a ketogenic diet.

Click Here to Get the FREE Body Mind Empowerment Handbook!


This answers the question: “How to train on a keto diet” quite nicely.

Low carb eating doesn’t hinder performance in the long run. You might experience a slight drop at first because you haven’t taught your body how to use fat as your primary fuel source. This energy crisis will be overcome after you’ve become keto-adapted. There are quite a few fat adapted athletes who have followed a well-structured ketogenic diet for a long period and are competing at a high level.

During aerobic activities, we’re already burning fatty acids and will do it even more efficiently when using ketones.

At higher intensities, we’re being glycolytic, but that’s because of the presence of no oxygen. Using even glucose is unsustainable at this rate. If our muscle glycogen stores are tapped off, then we’ll be able to perform anaerobically even when in ketosis.

Image result for keto adaptation

Keto-adapted training preserves our muscle glycogen stores and reduces catabolism. It’s a lengthy process and requires complete dedication. The better we become at burning fat, the better we’ll be able to utilize ketones and our own body fat for fuel.

  • During first weeks of adaptation don’t do high-intensity interval training.
  • You can do resistance training but not as often.
  • Focus on aerobic activities. Build up your fat burning engine.
  • Do a lot of yoga and mobility exercises.
  • After adaptation, start doing high-intensity training again.
  • Don’t train at glycolytic levels too often. Allow your muscle glycogen stores to be refilled with time.

In my opinion, it’s incredibly important for overall health as well as performance to efficiently use our own body fat for fuel.

In addition to nutritional ketosis, there are other strategies we can use for optimal health and longevity. I’ve written a comprehensive program about the ketogenic diet that will teach you everything you need to know about this way of eating and exercising.

It’s called KETO FIT and it includes all the information about the ketogenic diet, how it works, the fundamental principles of exercise, how to workout on keto, a 30-day meal plan, a 5-week workout routine, and many other bonuses.

Stay Empowered



Please enter your comment!
Please enter your name here

Comment moderation is enabled. Your comment may take some time to appear.