Low Carb Intermittent Fasting and Muscle Gain

Key Points
Studies show that an LCIF dietary approach is not detrimental to building muscle. Additionally low carb diets (due to being higher in protein) may help retain more muscle tissue than normal when dieting.

Low Carb Intermittent Fasting (LCIF) is an effective tool for weight loss, you can read more about the reasons why here. But how about gaining muscle when undertaking LCIF? or retaining hard earned muscle if switching from a standard diet?

Most people familiar with strength and conditioning understand how important nutrition is to the process of building muscle. With that in mind it’s only natural to ask:

  • Do fasting periods (when no calories are consumed) impact on potential muscle gains if training for hypertrophy?
  • Does LCIF impact muscle retention, especially if in caloric deficit?

LCIF and Muscle Gain – What the Science Says

The science is not completely settled when it comes to whether there are any advantages to building muscle when fasting. Clinical studies have shown potential but there are a number of variables to consider. This includes how fasting of any type affects energy levels and therefore performance in the gym along with caloric intake, including protein.

To gain muscle the body must be in a caloric surplus. This means you must be consuming more calories than your body needs to maintain its current state. With the exception of religious practice, fasting is almost always been used as a tool for weight loss. But, provided you are consuming enough calories, incorporating a high amount of protein and training with a high intensity, all things being equal (sleep, stress levels) there’s no reason why LCIF and muscle gain can’t be achieved.

Retaining Muscle

Intermittent fasting has demonstrated in clinical trials an ability to aid with muscle retention. Here’s just a few of the studies showing favourable outcomes.

These results indicate that fasting may help the body prevent muscle loss more effectively while dieting. From a weight loss perspective the more lean mass your body holds the better.

When dieting it’s natural to expect a loss of loss of lean mass along with fat loss. This is because the body is in caloric deficit. Retaining additional muscle tissue is beneficial, as muscle tissue is the most metabolically active tissue in the body. As a result it increases your metabolism. Intermittent Fasting may also combat Sarcopenia (muscle loss due to ageing) which is normally the result of a natural decline in Testosterone as we age.

Where does Low Carb Fit into This?

Clinical studies have demonstrated the benefits of low carb diet when it comes to muscle retention. Even when the subject is in a caloric deficit:

It would appear in some cases that when put on an extremely low daily caloric intake (500 calories per day) muscle loss was not recorded, even after 8 weeks. This isn’t the result of the low carbohydrate intake as such and is mostly attributed to higher protein, as an indirect result of lowering carbohydrate consumption.

How much Protein do I need to keep or grow muscle?

In most cases a good starting point is between .85 and 1 gram of protein per pound of body mass.

Recent studies have shown that less protein may also be effective however. As a result it’s best to track your progress. You can then make adjustments based on how your body is responding.

*It’s important to note for some, a high amount of protein may be unhealthy. For those with liver disease for instance, we recommend that you consult your doctor before making dramatic changes to your diet.


It’s not possible to provide a definite answer on whether LCIF provides benefits for building muscle. However it does seem to assist with muscle retention.

But, whenever discussing the human body, it’s just not that simple.

To build or preserve muscle standard protocols must be observed. This is regardless of your training or diet. For example you must be in a caloric surplus while consuming sufficient protein. You must also be stimulating muscle growth through strength training. Without these three conditions in place muscle gain will prove difficult.

Leave a Comment