Nutritional Ketosis for Strength Training

You can get all the benefits of a ketogenic diet and still gain strength.

“Fat is bad for you, your cholesterol is going to go up, and so will your risk of chronic disease.” This is what many of us have been told throughout our lives, and this view point has pushed by the media, trainers, and most of the health world for many, many years. Thankfully, things have changed.

Fat as a macronutrient is now being accepted as beneficial for our health (as long as it comes from good sources). Due to this acceptance of fat, more researchers and people have been experimenting with nutritional ketosis, which is extremely high in fat and low in carbohydrates. The concept is that nutritional ketosis allows the body to use fat as its main fuel source rather than carbohydrates.

The prevalent thinking today is that carbohydrates are needed with protein after workouts in order to help repair muscle tissue and promote strength gains, but is this really the truth? Can we train for strength on a ketogenic diet or are we destined to wither away into scrawny prepubescents?

In this piece I will discuss what nutritional ketosis is, what it means to be in nutritional ketosis, how to get there, how this influences our ability to strength train, and what to keep in mind while in nutritional ketosis during strength training.

The Skinny on Nutritional Ketosis

Nutritional ketosis means we are using ketones and fat as our primary fuel source not carbohydrates. Our mitochondria (the guys who make our energy) typically run on glucose if it is available. In nutritional ketosis this interaction shifts, and our body starts burning fatty acids and ketones in order to produce energy. The energy that can be produced from fat far outweighs what can be produced from glucose.1 Fat also burns much cleaner then glucose, which can result in less ROS (reactive oxygen species) which can damage DNA.2

Our body will always use glucose for fuel if it is available. That means if we are eating lots of carbohydrates we won’t be in nutritional ketosis. In order to enter nutritional ketosis we need to eat a low carbohydrate diet and deplete our glycogen. Glycogen is stored glucose found in the liver and in the muscles. When it is needed, like during a workout, our body will call upon that glycogen to be used for energy. Once all of the glucose is depleted then our body will look to fat for energy.

Once our glycogen is used up our body will start to mobilize fatty acids (fat) to be used for energy. However, fatty acids do not cross the blood-brain barrier easily, so our liver will start to create ketones for us.1 Ketones are water-soluble fat molecules that can readily cross the blood-brain barrier to be used for fuel. There are three ketones: acetone acetoacetate, beta-hydroxybutyrate, and acetone.

One of the fastest ways to get into ketosis is through fasting for 24-48 hours. Someone who is eating a high carbohydrate diet would likely need closer to 48 hours. The transition to ketosis can cause some adverse symptoms like headache, irritability, etc. This process can be made easier through the use of exogenous ketones/ketone supplements which give our body fuel to use before we have started to produce our own ketones.

There is no one size fits all approach to anything, especially nutrition.

The Measurement of Ketosis

We enter ketosis when we have a certain level of blood ketones. The minimum level of blood ketones needed to enter ketosis is 0.5 millimolar. For best results we would like our blood ketones to be between 1–3 millimolar. If our blood ketones get too high, then we can enter ketoacidosis and issues can arise. Measuring your ketone levels is a good idea to ensure you are in a state of beneficial nutritional ketosis.

There are different tools you can use to measure your blood ketones at home, such as the Precision Xtra Blood Glucose & Ketone Monitoring System.

Maintaining and Increasing Strength During Ketosis

The old adage is that you need carbohydrates in order to provide your muscles with the fuel needed to push yourself in the gym and to refuel your body after exercise. During nutritional ketosis we are running off fat, and fat provides a lot of energy for our body and our muscles to use. Energy is energy (ATP) if we have it, and if it is bioavailable we can use it in order to push larger amounts of weight or preform well.

Nutritional ketosis has been shown to improve aerobic ability and keep strength up.3 Contrary to Gatorade’s ads, high levels of carbohydrates are not necessarily needed in order to perform athletically. For most strength-building exercises, short bouts of intense effort will call upon the creatine-phosphate energy pathway. That pathway does not rely on carbohydrates or fat but instead relies on amino acids. If you are trying to build strength, taking a creatine supplement when in ketosis is a good idea.

An example of how nutritional ketosis doesn’t affect strength is seen through a study of elite gymnasts.4 After 30 days of being in ketosis, the gymnasts saw no reduction in their strength, but they did see an improvement in their body composition and body-fat percent.

Muscle Loss and Ketosis

Our body can create glucose from amino acids, and preventing this is imperative to keeping ourselves in ketosis. Ketones themselves help with this since they are anti-catabolic. This means that they help to prevent breakdown of the body. They specifically have an anti-catabolic, protein-sparing effect. This means if our blood is flooded with ketones, our body is less likely to liberate amino acids from our skeletal muscle for fuel. This is because the ketones replace the glucose as the primary energy. This prevents muscle wasting and the loss of strength as well.

How to Implement Nutritional Ketosis

A traditional ketogenic diet (which is lower in protein) is not ideal for a strength athlete. A modified Atkins diet can be better idea for many because it is a little less restrictive: 70% of calories come from fat, 25% from protein, and 5% from carbohydrates. This increased protein intake gives a strength athlete a better ability to recover and heal from intense exercise sessions.

Using a fast of 24-48 hours is an effective way to start to enter into ketosis. Fasts are great for a variety of reasons, and this includes giving your digestive system a break. The use of exogenous ketones (like ketone esters) can help one enter ketosis and gain some the benefits of ketosis. The use of ketone esters has been shown to help the performance of endurance athletes.5 Even though endurance athletes are not the same as strength athletes, strength athletes can still benefit from the use of exogenous ketones.

Supplementing with medium-chain triglyceride (MCT) oil or coconut oil can be an effective way to get all the necessary calories from fat. When someone enters nutritional ketosis they will typically find their appetite goes down as ketones have an appetite-supressing effect. This may end up with some calorie restriction which isn’t always a bad thing. Insulin sensitivity decreases as we age, and that decrease can lead to the development of a variety of chronic issues. Calorie restriction can combat this by increasing our insulin sensitivity.

Insulin is important when it comes to building strength and muscle. Insulin is an anabolic hormone, meaning it helps us to build. Whenever we are trying to increase size and/or strength, insulin becomes important. We must stay sensitive to insulin for it to be effective. Insulin secretion is stimulated by elevated levels of blood glucose, which is the result of eating carbohydrates and amino acids. When we eat protein and break it down into amino acids, this will stimulate an insulin release.6 We need that release to help insulin shuttle amino acids into our tissues. This helps to increase protein synthesis in some of our tissues (faster recovery), and stimulates fat to enter our cells which can then be used for energy.7 Insulin plays an important role in nutritional ketosis, and it is imperative to keep our insulin sensitivity high if we want to keep up our strength.

There are other benefits to ketosis. One of the three ketones, beta-hydroxybuterate, has beneficial effects on endogenous antioxidants production, and helps to protect genome stability (ie: preventing the development of cancer cells).8 It has also been shown to prevent inflammation from the NLRP3 inflammasome, which drives the inflammatory response in a handful of disorders including Alzheimer’s disease, autoimmune diseases, and type 2 diabetes.9

Ketosis Is Not for Youth

Nutritional ketosis is not a good idea if you are a younger individual looking to increase strength and size. When you are younger, you are more sensitive to things like IGF-1 and insulin; both are anabolic (help you get bigger). If you are eating a ketogenic diet you will not be able to take full advantage of these, and you may miss out on some of your genetic potential. As we discussed, increased blood glucose is the main driver of insulin secretion. As we get older we become less sensitive, and it no longer becomes as important to maximize IGF-1 and insulin.

Is Nutritional Ketosis for You?

Something a lot of nutritional experts will overlook is the fact that we are all individuals. There is no one-size-fits-all approach to anything, especially nutrition. Different people react better to different ratios of macronutrients then others. For example, I run great on a high-fat diet while my friend feels like garbage if he has too much fat. The key is finding what works best for you and your goals.

Ketosis can help you maintain and increase your strength. It is also a great tool if you want to lose body fat. But it is not for everyone. Women typically have a harder time getting to ketosis, and may feel more adverse symptoms as their body switches from carbs to fat for fuel. Remember that you are an individual. Find what works best for you while eating high quality ingredients.

More on ketones:

Why a Ketogenic Approach to Nutrition Is Ideal for Your Health


1. Phillis A. Batch. Prescription for Nutritional Healing. October 2010.

2. Phillip Stafford, et al. The ketogenic diet reverses gene expression patterns and reduces reactive oxygen species levels when used as an adjuvant therapy for glioma. September 2010. Nutrition & Metabolism.

3. Rhyu HS, Cho SY. The effect of weight loss by ketogenic diet on the body composition performance related physical fitness factors and cytokines of taekwondo athletes. October 2014. Journal of Exercise Rehabilitation.

4. Paoli A, et al. Ketogenic diet does not affect strength performance in elite artistic gymnasts. July 2012. Journal of International Society of Sports Nutrition.

5. Cox Pj, et al. Nutritional Ketosis Alters Fuel Preference and Therby Endurance Performance in Athletes. August 2016. Cell Metabolism.

6. John C. Floyd, et al. Stimulation of insulin secretion by Amino Acids. Vol 45, No, 9, 1966. Journal of Clinical Investigation.

7. George Dimitriadis, et al. Insulin effects in muscle and adipose tissue. August 2011. Diabetes Research and Clinical Practice.

8. Rhyu HS, Cho SY, Roh HT. The effects of ketogenic diet on oxidative stress and antioxidative capacity markers of Taekwondo athletes. December 2014. Journal of Exercise Rehabilitation.

9. Yun-hee Youm, et al. Ketone body beta-hydroxybutyrate blocks the NLRP3 inflammasone-mediated inflammatory disease. March 2015. Nature Medicine.

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