Why Am I Losing Muscle On Keto?

There are multiple different fitness fads popular today. There are different types of diets and different types of fasting gaining popularity these days.

With so many options, it can be hard to make a choice. Regardless, many people are going with the keto diet. The keto diet is becoming popular like nothing else.

But, many people on the keto diet, unfortunately, notice they lose muscle quickly on this diet.

So, why am I losing muscle on keto? Well, keto is a bad diet for bodybuilders as it often causes muscle loss due to the low carbs (even if it’s a great diet for losing fat!)– and it makes it basically impossible to gain muscle either. While it is possible, there are “modified” versions of keto and other diets that work much better to save and/or build muscle.

Why Am I Losing Muscle On Keto?
Why Am I Losing Muscle On Keto?

Understanding The Keto Diet

The Ketosis Process

Ketosis is a special that happens in the body when the body does not have enough carbohydrates to burn.

In such a situation when the body’s primary energy resource (carbohydrates) are not available for use, the body turns to its second source of energy, fats.

Now, obviously- a diet that causes you to burn fat is unsurprisingly popular! And just for reference, I used to do the keto diet myself for a year. I LOVED it- but there are a few downsides.

As the body begins this process, molecules called ketones are produced. These can be used for energy by the body. The keto diet or the ketogenic diet is named after this substance.

The Ketogenic Diet

The ketogenic diet is described as very low in carbs and high in fats. The diet shares many similarities with other low-carb diets such as the Atkins diet.

In a keto diet, a minimum amount of carbohydrates are included and instead, fats are included. When the body can’t find enough carbohydrates for use, the body switches to using fats for energy, this is when it produces a substance called ketones on which the diet is named.

There are different types of ketogenic diets, let us take a look at them:

  • Standard keto diet: This is the most basic keto diet. It generally contains 70% fat, 20% protein and only 10% fat.
  • Cyclical keto diet: This is a special type of keto diet that involves periods of carb refeeds. An example would be 10 ketogenic days followed by 2 high carb days
  • Targeted keto diet: This is yet another special type designed for people who hit the gym. Here, we have the facility to include carbs in the diet near times of workout. 
  • High protein keto diet: This is a keto diet designed to focus on protein. The distribution is often 60% fat, 35% protein and 5% carbs.

The Role of Carbohydrates in Building Muscle

Let us try to understand the very important role that carbohydrates play in the body. Think of the body as a car. It needs fuel to run. The body gets this fuel from, you guessed it, carbohydrates.

We naturally obtain carbohydrates from the foods we eat. Foods such as breads, cereals, rice, etc contain ample amounts of carbohydrates. Once the carbohydrates reach the body, it is converted into glucose which can be reacted inside the cell to release energy. Our body uses this energy to do different types of work. 

Now, the argument is- our fat cells contain glucose and we burn the fat to produce that sugar instead. While this is right- there’s one problem.

Our body refuses to burn fat AND build muscle at the same time- and scientists (even I!) are unsure why. It’s generally believed our body just doesn’t like having to break our reserve energy down to build muscle as muscle is so energy expensive. It is theorized our body sees this as very inefficient.

So, this is the main role of carbohydrates in building muscle. Without a surplus of carbohydrates (nor protein), our body just refuses to really build muscle.

Why You Are Losing Muscle On Keto

The reasons for this are simple. We already understand the keto diet. It is extremely low in carbohydrates and high in fats.

So, here’s the thing. Our body, again- for some weird reason, refuses to burn fat AND build muscle. Muscle requires a TON of calories to maintain, and it’s theorized by scientists our body sees this as a very inefficient thing to do- build muscle and burn fat.

Think of our ancestors. Would it make sense for them to be starving- burning fat, and building something that requires EVEN MORE energy? This would probably lead to us dying from lack of food!

It’s basically like using the reserve gas in the car to drive EVEN FASTER! It’s a massively bad idea.

Nowadays, we just have a surplus of food everywhere- but we need to remember our evolution and where we came from as humans. Nowadays we WISH our body would do this as we would look shredded, but it didn’t necessarily make sense for our ancestors.

Keto Also Depletes Energy in The Gym

Remember that your body does have an energy source – the fats from your keto diet. But there is a problem with the setup. You require quick energy at the gym as you are using different muscle groups at different intervals.

And the problem is that fats have trouble providing that. Fats are indeed a source of energy, but they are a slow source of energy.

On the other hand, you need a fast source of energy like carbohydrates for use in the gym. The result is that you are able to make less power in the gym than usual. As time goes on, you continue to workout with less intensity and ultimately you start to lose muscle.

How To Minimize Muscle Loss On Keto

If you’re looking to minimize muscle loss on keto- you should try taking BCAAs. BCAAs are just like creatine in a sense, it’s a powder you mix into your drink and it puts amino acids in your blood stream.

These amino acids are proteins- and it ‘tricks’ your body into thinking you have more protein than you do. This encourages your body to NOT break down muscle, which can be common on the keto diet.

BCAAs are incredibly common- even if you’re not on keto. A lot of bodybuilders take it before sleeping or when they wake up to keep the muscle-building going.

BCAAs will help reduce muscle loss on keto, general fasted cardio, and many other diets. While it cannot absolutely stop muscle loss nor guarantee muscle retention- many bodybuilders swear by it.

How To Workout With Keto

Firstly, if you want to stay in keto, there is still an option to keep following and still not lose muscle. That is the targeted keto diet that we talked about before.

The targeted keto diet includes taking carbohydrates only near workout times so performance at the gym is not reduced. At other times it feels like a normal keto.

The other option is obviously to give up the keto diet entirely and start following a dedicated diet plan made for bodybuilders.

While this doesn’t give the same muscle growth normal bodybuilders may experience- it still gives better than the normal keto diet.

Want to Bodybuild With Fewer Carbs? Try Fasted Cardio instead of Keto

If you’re interested in bodybuilding with less carbs- you may want to try fasted cardio instead of keto.

It’s kind of similar, you do fasted cardio in the morning for that intense fat loss- but you eat normally when you go to do the weight lifting.

You might’ve heard of this- fasted cardio in the morning, weights at night. Many super serious fitness freaks do this, they do their fasted cardio right when they wake up, have a small snack, then weight lift. This maximizes fat loss, muscle retention, and will get you absolutely shredded.

(I mean really, you burn like 4000 calories a day doing this, it’s almost impossible to GAIN weight)


The keto diet has been gaining a lot of traction. It is a good diet plan for losing weight but it is certainly not for bodybuilders. While it’s great to burn fat, it’s not exactly great for actually putting on muscle nor keeping it.

You can try BCAAs to help reduce the muscle loss- but they don’t always work.

If you can, it’s best to stick with the carbs if you want to put on muscle. Otherwise, you’re playing bodybuilding on max difficulty. That’s also not to mention the potential health risks of keto- physicians still aren’t in agreeance if keto is a good idea.

So, if you notice a lot of muscle loss on keto- you might want to try a different diet, or doing targeted keto where you increase carbs when you workout.

Regardless, keto and bodybuilding isn’t a great idea. It’s a great diet for fat loss, and might be great if you’re actually trying to ‘cut’ weight for a bodybuilding competition, but if you’re trying to gain muscle, you may want to try something else.

Leave a Reply