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Ketogenic Nutrition and Exercise

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Quick Summary tl;dr

Studies show that a the ketogenic diet does not negatively affect performance in athletes. Studies also show that the ketogenic diet will help you preserve and build muscle mass.

We need to embrace personalised nutrition. Those who are insulin sensitive will, in general, do better with carbs-ups compared to those who are carbohydrate intolerant and insulin resistant. Keep in mind that carbs are not responsible for the obesity epidemic. It is the overconsumption of carbs, processed foods and changes in lifestyle.

When considering carb-ups, type of exercise matters: Those who do high intensity exercise and need to be able to perform explosive actions will benefit from carb-ups. Extra carbs may be beneficial for activities like CrossFit, sprinting, etc.

Carbs-up are not an excuse for bingeing: adding carbs is not an excuse for eating sugary foods, pizza or chips!

You can read even more about protein and exercise nutrition in this post: Ketogenic Nutrition and Exercise: Protein and Ketogenic Nutrition and Exercise: Carbs

Table of Contents

In my previous post, How to Exercise on a Keto Diet, I outlined some of the basic facts about exercise and the most common myths. In this and future posts, I'd like to focus on nutrition aspects of exercise. Foods containing carbs are not all evil and I'll explain when clean paleo-friendly carbs can be used even on a keto diet. Let's start by busting some of the most common myths...

Carbs and Performance

Do we need carbs for better performance? One of the most common myths is that low-carb eating will negatively affect your performance. This is down to studies that ignore keto-adaptation and only focus on the immediate effects of carb restriction. There is, indeed, a transitional period in which performance drop occurs but it only lasts for a few weeks.

Once you get keto-adapted (usually 3-4 weeks), your body will switch from using glucose to using ketones and fatty acids as the main source of energy.  This study performed on elite athletes shows that a keto diet does not affect strength performance. Eight athletes over a period of 30 days were fed virtually a zero carb diet and didn't experience any drop in performance. In fact,  more and more studies are showing the beneficial effects of keto-adaptation.

Ketogenic Nutrition and Exercise: Carbs

Even athletes that are doing very long cardio training or marathons can follow a keto diet. Timothy Allen Olson is just one of the many super athletes who have proven to be thriving almost purely on a diet that is best described as low-carb, keto and paleo. However, Timothy doesn't follow a standard ketogenic diet - he eats carbs strategically. Before or after his workouts he eats clean carbs such as sweet potatoes and fruits. He also uses glucose gels on training runs. Everyone is different and although some may thrive on a Standard Ketogenic Diet, others may benefit from adding some carbs. On his website, Timothy says: "I believe each person/body is very unique and you need to find the best way of eating for yourself, each body accepts or rejects foods differently."

Some people can tolerate more carbs than others. Those who are insulin sensitive will, in general, do better with carbs-ups compared to those who are carbohydrate intolerant and insulin resistant. Carbohydrate intolerant individuals should, in general, avoid carb-ups.

Carbs and Muscle Growth

Another common myth is that you won't be able to gain muscle mass or even that you will lose muscles on a keto diet. The assumption is that you will not be able to gain muscles without the carbs to trigger an insulin response.

Ketogenic diets have shown muscle-sparing effects. Jeff Volek and Stephen Phinney have published several studies on both performance and muscle-sparing effects which they also analysed in their best-selling books (The Art and Science of Low Carbohydrate Living and The Art and Science of Low Carbohydrate Performance).

Muscle gain on a keto diet is slow but definitely pays off (less chances of gaining body fat). So unless you want to achieve maximum anabolic effects (bodybuilders), you won't need to add carbs to build muscles.

Ketogenic Nutrition and Exercise: Carbs

So if carbs are not vital for muscle growth, what are the main factors?

Adequate Protein Intake

This depends on your lean mass and activity level and is 0.6 - 1 grams per pound (1.3 to 2.2 grams per kilogram) of lean mass. The more you exercise, the more protein you will need. Too little protein will lead to muscle loss. You can learn what your ideal level is by using our keto calculator.

Calorie Surplus

If you want to gain muscles, you have to eat more. About 10-15% over your maintenance level is ideal. When you follow a ketogenic diet, calorie surplus will translate into increased fat intake (carbs and protein remain the same).

Proper Training

You have to do the right type of exercise to promote hypertrophy (the process of individual muscles increasing in diameter). The right type of resistance training is crucial for muscle gain.

Don't Overtrain

Your body needs time to recover, otherwise it would be counterproductive and you may actually lose muscle mass. This doesn't mean your "resting" days have to be inactive - you can do light cardio instead.


Just like weight loss, muscle growth won't happen without proper sleep.  This review article lists several negative effects of sleep deprivation. Sleep deprived individuals produce less growth hormone, have impaired glucose metabolism and show a decreased level of leptin - the hormone that signals satiety. On the other hand, they show an increased level of ghrelin - the hormone that tells the brain when we are hungry. People who are sleep deprived are likely to store more body fat, so try to get at least 7-9 hours of sleep every day.

Want to know how to gain muscles, lose body fat or maintain a healthy weight on a keto diet? Discover your ideal macronutrients using our keto calculator.

When Do I Need to Carb-Up on Keto?

Carb backloading, carb nite, carb day,... all these are different names for carb-up techniques. There is no approach that universally works for everyone and we simply need to embrace personalised nutrition in order to determine the best method for everyone.

Ketogenic Nutrition and Exercise: Carbs

Fat Loss and Weight Maintenance: No Need to Carb-Up

Will I need extra carbs? Most likely, no you won't. If you want to lose body fat, you should avoid large amounts of carbs. You probably have enough body fat that can be used for energy. If you want to avoid carbs but still need more energy, you can add some MCT oil or coconut oil to boost your energy levels. Again, you'll have to try this yourself. Some people tolerate MCTs well while others may experience stomach distress.

If you want to maintain your weight, you won't need large amounts of carbs unless you're doing an intense exercise for extended periods of time and experience issues with muscle recovery.

Muscle Gain: It Depends

Will I need extra carbs to gain muscles? Maybe, it depends on what you want to achieve. Apart from the Standard Ketogenic Diet, there are variations which allow extra carbs. On the Targeted Ketogenic Diet (TKD), you eat carbs strategically round your workouts to maintain performance without interrupting ketosis for too long. The Cyclic Ketogenic Diet (CKD) is used by advanced individuals, mostly bodybuilders, for maximum muscle growth and sustained performance. CKD and TKD are not suitable or advisable for the vast majority of people. Be aware that it's easy to consume excessive carbs and gain body fat if you use the CKD approach.

If you want to try TKD or CKD, you should already be quite lean. For a TKD, avoid fructose based foods and go for glucose based foods instead. Unlike fructose which will interrupt ketosis (replenishes liver glycogen), glucose will be used as an immediate source of energy (replenishes muscle glycogen). This is a great resource for both CKD and TKD approach - check it out if you are interested in this type of ketogenic diets.

You should never use the Targeted or Cyclic Ketogenic Diet as an excuse to eat extra carbs. These diets are only suitable for advanced athletes and bodybuilders who want to enhance their performance and maximise muscle growth.

Explosive Exercise Actions (HIIT): Yes You May Need To Carb-Up

What is explosive exercise? Explosive exercise builds power, strength and fitness faster and can be defined as movements in which the rate of force development is maximum or near maximum.

Whether you'll need carbs or not also depends on the type of exercise. For the vast majority of people, extra pre or post workout carbs are not needed. However, if you do CrossFit, sprinting and other high-intensity activities which require explosive actions, extra carbs can be beneficial for sustaining strength.

Have you tried carb-ups? Let me know your thoughts!

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Martina Slajerova
Creator of

Martina Slajerova

I changed the way I ate in 2011, when I was diagnosed with Hashimoto’s, an autoimmune disease that affects the thyroid. I had no energy, and I found it more and more difficult to maintain a healthy weight.

That’s when I decided to quit sugar, grains, and processed foods, and to start following a whole-foods-based ketogenic approach to food.

About the Reviewer

This article has been reviewed by Franziska Spritzler, RD, CDE who is a qualified expert. At KetoDiet we work with a team of health professionals to ensure accurate and up-to-date information. You can find out more on the About us page.

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Comments (17)

I’m starting out on a low carb diet (aiming for max 20g a day) due to historic injuries and my job becoming less active, I’ve piled the weight on over the last three years. Over the last 9 months I’ve got back into kickboxing and overcome my injury to a point where I feel I’m ready to up my training.
I will be looking to kickbox 3 times a week (with occasional heavy sparring sessions, knee depending) and if possible 2xHIIT. I have a lot of weight to loose, so the keto diet suits me (I also hate most carb type foods) but should I be adding extra carbs? Or aim for the low 20g?

When in ketosis and engaging in HIIT training such as CrossFit and OrangeTheory, what is the general recommended amount of carb intake in grams as a percentage of the day's caloric intake?  There's literature out there about consuming carbs either before and/or after exercise.  Do you have a preference or do you see a benefit in either?  How to gage how much carb will be "spent" during a workout and if you don't add the carbs pre or post workout, is it dangerous or does it halt the weight loss process?

I have been on keto for 8 months. Its going very well. I am 60 yrs old. I am currently training fora sprint triathlon in 2018. None of the Triathlon sites seem to understand keto, they all promote energy bars and energy drinks which of course are loaded with carbs. Any suggestions for what to have on hand DURING the race for added fuel???

Hi, thanks for an amazingly well researched website. Is there an app coming soon on the iphone?
I was a vegan before recently turning to the keto diet, initially for fat loss. I do intend to work out a way to be healthily vegan on a ketogenic diet, and will share if I make interesting discoveries along the way.
I came here looking to see if I can justify a higher number of vegetable based carbohydrates by doing more exercise. You recommend glucose over fructose if doing HIIT and similar due to the muscle glycogen being prioritised during the workout. Can starchy sources of carbs (i.e. vegetables) therefore be eaten more freely, if afterwards some kind of resistance training was involved?
Would this also be true of sports like football or squash? i.e. Can a vegetarian keto athlete get away with eating more starch based carbs and maintain ketosis? How much of a difference does time make - i.e. eating at midday and exercising at 1, or eating at 10 am and exercising at 8pm?
Thanks very much.

Thank you Joe! It is available on the iPhone since January 2017:
Yes, depending on the exercise, you can have more post workout carbs from vegetables. If I have a really intense training (HIIT), I sometimes eat sweet potatoes after my workouts. I generally tend to eat more carbs after my workouts but it's not something I always plan for. Sometimes I even skip meals, it depends how I feel.
You can maintain ketosis with more carbs but you will likely not maintain it continuously. You will temporarily be kicked out of ketosis after a carb up. Some types of exercise (HIIT types of exercise) are better with carbs ups while other types (resistance training) won't require carb ups.
When it comes to time, sooner is generally better (you should avoid exercise 2-3 hours before bed). I usually exercise round midday on an empty stomach but that's because I'm not hungry and rarely eat breakfast.

Hi Martina!
Can you kindly share with us what does a post workout meal/snack on keto looks like? Many thanks!

Hi Farah,  I just make sure there is enough protein and also some fat (but not too much). Sometimes I just skip a meal altogether - if I don't feel hungry, I don't eat. Here's what I usually have...
- If it's just a quick snack, I'd have a few slices of beef jerky: Soft & Tender Homemade Beef Jerky
or a handful of almonds or a protein shake (coconut milk + water + whey protein powder).
- If it's a full meal, I usually go for fish (salmon, tuna, sea bass, ...) with steamed broccoli + extra virgin olive oil + lemon juice. Or I have a portion of steak, pork chops, lamb chops, chicken, slow cooked meat, etc with salad (usually Greek Salad: Authentic Greek Salad or some Guacamole: Quick & Easy Chunky Guacamole)
- I rarely do carb-ups but when I do, I'd have a sweet potato or some root vegetables with meat.

I really like the keto lifestyle and I've been doing it for about 3 month it helped my boyfriend a lot with his migrane but do you also have recommendations for athletes? I do train 5x a week 2x a day, these training sessions variy from heavy lifting, to strength traing, sports specifiy skill training and High Intensity Crossfit Workouts. All days are different some are strength oriented, some are more focused on maximum areobic output. At  
I do struggle a bit to find the right caloric intake for the level of activity since it varies so much and I although I am athletic i still want to loose some bodyfat. Do you have any recommendations?
thank you cheers

Hi Martina, there's a lot to discuss and I'll definitely write a post at some point 😊 For the science behind it, I'd recommend The Art and Science of Low-Carbohydrate Performance by Volek & Phinney.

hi martina ..
    I am from Saudi Arabia , we have ablog in arabic about low carb diet , and I have an idea to add to this app ..
   I am in low carb diet scince 2 years , and I have some lowcarb recipes I want to share with you and other customers who have been used this app .. can you make an option if we want to add some recipse ..
Thank you for this app it's very helpfull , and I really enjoy it ..

Hi Walaa, thank you! Did you maybe mean guest-posting? Or is there any recipe you would like to see in the app?

I mean in the app if i want to add recipes..

I really appreciate it. However, we have been working on a universal KetoDiet app right now and won't be able to work on additional features until it's done. I think what you suggest is great idea but also requires a lot of work - right now the universal app is our priority. We'll consider adding this feature in the future updates. Thank you!

Hi Martina, do you think that I it's a good idea to do carb-ups to balance hormone levels? I've heard that low-carb eating can mess them up. Do we all need to do carbs ups then?

I do not need carb refeed not yet any as I am 80 pounds over weight and am doing very well with 20 or less grams of carbs a day

This is something I'd like to focus on in one of my future posts - together with zero-carb diets and their actual purpose. Many people do well without carb refeeds (for hormone balance) but some seem to be doing better with small carb-ups. Whether you need them or not depends on several factors and I'll get to it in more detail in my upcoming post.

Hi Carol. I don't know if you need carbs ups but they helped me stick with the diet. I didn't do well on a VLCKD diet which I followed for a few months. I do carb ups every week or two and it has really made a difference to my hormone balance. I don't eat loads of carbs but have a meal with 3-4 times more carbs than what I'd usually eat.... not like carb backloading where you eat hundreds of grams of carbs if you know what I mean.