Ketosis and Fasting: Do BCAAs Break a Fast or Ketosis: Thomas DeLauer

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Ketosis and fasting: BCAAs break a fast or ketosis: Thomas DeLauer

Overview of ketosis

Ketosis is a metabolic state that occurs when dietary carbohydrates are found in such low amounts that your body must depend almost exclusively on the oxidation of fatty acids and the metabolism of ketones.

A traditional ketogenic diet allows to reduce carbohydrates to around 5% of the total energy intake with a maximum carbohydrate limit of 50 g per day.

In short, a ketogenic diet causes the body to use and burn fat, instead of carbohydrates, as a fuel (energy)

Summary of BCAA

Amino acids are the building blocks of proteins. Branched-chain amino acids (BCAAs) are so named because of their structure, which includes a "side chain" of one carbon atom and three hydrogen atoms.

BCAAs are the only non-degraded amino acids in the liver.

All the other amino acids are regulated by the intestine and the liver before circulating through the rest of the body.
This means that the dietary intake of BCAA directly influences plasma levels and concentrations in muscle tissue (Layman DK 2003). Interestingly, BCAAs are burned for energy (oxidized) during exercise, so they are also an important fuel exercise.

So this raises the question … If it can be used as fuel, can it break fast?

BCAAs, however, go directly to the bloodstream. This means that the dietary intake of BCAAs directly influences plasma levels and concentrations in muscle tissue

There are three BCAAs: leucine, isoleucine and valine

The administration of BCAA can reduce muscle pain, accelerate recovery, promote muscle protein synthesis and support fat loss (1,2)

Ketosis and insulin

The main purpose of insulin is to regulate the metabolism of fats and carbohydrates. The digestive system breaks down carbohydrates, such as sugars and starches, into a molecule called glucose.

Insulin allows your body's cells to absorb glucose so your body can use it as fuel, which ultimately lowers glucose levels in the bloodstream.

Ketosis and insulin

Ketosis will take place when the body needs energy and there is not enough glucose available for the body.

This happens when the body lacks insulin and blood glucose levels rise.

BCAAs can inject insulin

Studies have shown that branched-chain amino acid supplementation increases insulin levels and free fatty acid concentrations

Leucine, specifically, stimulates glucose uptake for up to 45 minutes (3,4)

Study of Insulin and Ketosis

Although there are some benefits of supplementing BCAAs, it may not be advisable to do so in a ketogenic state.

In one study, a man voluntarily fasted for 50 days.

Their ketones were high (14 mmol / l) and they injected insulin (around 0.1 IU / kg, so around 7-8 IU).

For 30 minutes, your ketones and blood sugar decreased and there was a massive absorption of ketones by the brain and the production of ketones stopped.

However, in 30 minutes their ketones started firing again

In summary, a peak of insulin can expel you from ketosis, even temporarily, since the clearance of insulin is apparently rapid (5)

BCAAs in ketosis (increase in circulating BCAAs)

In one study, the dietary replacement of carbohydrates by fat was studied in six healthy subjects, which was preceded and followed by a period of 3 days of balanced diet.

During the ketogenic diet, the levels of free fatty acids, glycerol and 3-hydroxybutyrate increased significantly and glucose levels decreased by 16.5 +/- 3.2%

The hormonal pattern changed to a catabolic mode with a drop in insulin levels (-44.0 +/- 6.3%) and an increase in glucagon concentration (+39.0 +/- 10.4%).

The average levels of gluconeogenic amino acids (alanine, glutamine, glycine, serine and threonine) were reduced by 8-34%, while those of the branched chain amino acids increased by more than 50%.

He concluded that a ketogenic diet may result in an increase in circulating BCAAs in the body, so supplementing with BCAA may be even less necessary during ketosis (6)


1) All about BCAA | Precision nutrition (North Dakota.). Obtained from

2) Ten advantages of BCAA | Article of Poliquin. (North Dakota.). Obtained from

3) The ketogenic diet and insulin resistance | He governed me. (North Dakota.). Obtained from

4) Ketosis: what is ketosis, the effects of ketosis and ketosis levels. (North Dakota.). Obtained from

5) Hyperlipid: Fuel and neuron function. (North Dakota.). Obtained from

6) Hormonal and metabolic changes induced by a isocaloric isoprotein ketogenic diet in healthy subjects. – PubMed – NCBI. (North Dakota.). Retrieved from

Video credits to Thomas DeLauer YouTube channel

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    Ketosis and Fasting: Do BCAAs Break a Fast or Ketosis: Thomas DeLauer

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