Does Glutamine Break a Fast?

5 min read

The topic of supplements and intermittent fasting is a very debated one. Most people look at calories and especially the number of carbs and protein to decide whether something will or won’t break a fast. Their goal is to only have foods under 1 gram of carbs, or supplements that won’t cause an insulin response. Others believe even vitamins and minerals should be avoided because they go against the classic definition of a fast, which implies no nutrients whatsoever, only water.

Taking all this into consideration, does glutamine break a fast?

The common consensus is that yes, glutamine and all amino acids break a fast. They take you out of ketosis and autophagy and may even cause an insulin response. Others, especially bodybuilders, recommend using glutamine during a fast.

So let’s dive deeper into this topic and see when you should avoid glutamine during a fast, when you can benefit from it, and more.


What is glutamine?

Glutamine is an amino acid. Its main role is to serve as a building block for proteins. It comes in two forms: l-glutamine and d-glutamine with the first being more commonly used in protein supplements. That’s because d-glutamine has little to no effects on humans, all the benefits come from l-glutamine.

Glutamine can be found in foods and it is also produced by the body. However, your body’s ability to produce this essential amino acid doesn’t always match your needs for it. For instance, in case of an injury or an illness, supplementation is often required for rapid recovery. Athletes and bodybuilders may also be unable to get the necessary glutamine quantity without supplementation.


Does glutamine break a fast?

The answer depends mostly on why you’re fasting and what type of fast you’re on. If you’re on a strict water fast, with maybe unsweetened tea and coffee and a goal to stay as close to zero calories as you can, glutamine is off-limits. The same goes for those with blood sugar issues. Supplementation with amino acids and glutamine specifically should be done with caution.

 Studies suggest glutamine increases blood sugar levels. In other words, it causes an insulin reaction that breaks your fast. If you’re fasting for gut rest, the news isn’t any better as glutamine will stimulate the gut, breaking this type of fast as well.

The only people who may be able to supplement with glutamine without worrying are those who are dirty fasting. This includes athletes or bodybuilders who are trying to cut and lose weight quicker, without losing any muscle.

In these cases, the main goal of fasting is losing fat, usually while gaining muscle and maybe reducing the inflammation that naturally occurs after an intense workout. As a result, supplementing with amino acids, including glutamine is helpful and the small insulin response that may happen won’t affect the overall goals of the fast.


Does glutamine powder break a fast?   powder

The answer is exactly the same as before. The only issue powder introduces is that of added sugars or sweeteners. As long as you make sure you’re having unflavored, unsweetened glutamine powder, the answer will depend purely on the type of fast you’re on and the reasons you have for fasting.

Flavored or sweetened powders add new ingredients to the mix that may have more unwanted effects and break your fast regardless of your goals.


How does glutamine help intermittent fasting?help

If you’re someone who is trying to lose fat but you don’t want to lose weight overall, instead you want to gain lean muscle, supplementing with glutamine during your fast will be helpful. The truth is, when fasting for an extended period of time, there’s a risk to lose some muscle mass.

For most people, this isn’t an issue as the loss isn’t significant and the risk can be diminished by doing some easy workouts. Bodybuilders who want to have a lot of lean muscle mass cannot afford to take such a risk because it might slow down their athletic efforts.

In this case, supplementing with glutamine is a good solution. Yes, there might be some insulin response to it, but the overall benefit of the fast – reduced inflammation and caloric deficit is maintained without the risk of losing muscle.


Side effects of glutamine

Since glutamine is an essential amino acid found in various foods and produced naturally in the body, it is generally very well-tolerated by everyone. Someone who doesn’t supplement will typically get somewhere between 3-6 grams of glutamine per day, depending on their diet.

Several studies have been conducted regarding supplementing with glutamine with doses ranging from 5 grams to 45 grams per day for up to six weeks. The results showed no side effects. However, blood safety markers were not examined even in the highest doses. In other words, we can’t say supplementing with very high doses is 100% safe, but no immediate side effects appear.

Short-term use is generally deemed safe. Some scientists do express concerns regarding long-term supplementation. Also, the effects will vary from a person who eats a high-protein diet, rich in animal products versus someone who eats plant-based. Animal products, such as eggs and meat are high in glutamine, so you’ll be getting a good amount from food alone. Someone on a plant-based diet will not get as much glutamine from foods, so they might react differently to supplementation.


The bottom line

Does glutamine break a fast? Yes, if you’re following the classic definition of a fast that requires close to no carbs or protein and bans any foods or supplements that could create an insulin response.

If you’re following a modified type of fast with the sole intention of losing fat, but not weight, supplementing with glutamine may be allowed and beneficial. Pay special attention to powders and choose an unflavored, unsweetened option to avoid a high increase in blood sugar levels.

Because it is found in foods and it occurs naturally in the human body, glutamine supplements are generally well-tolerated even in higher doses, though caution is recommended, especially with long-term use.

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2 thoughts on “Does Glutamine Break a Fast?”

  1. Thanks FOr the info, it was helpful. Just an fyi though, twice you refered to glutamine as an essential Amino acid. It is not. It is a non-essential amino acid. If the body makes its own supply, it is not essential that we consume it Through our fooD.


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