In healthy young adults, administering insulin without providing amino acids leads to a 20–40% increase in the activity of genes involved in mitochondrial function after 7 hours, indicating that...

Pro

Against

Mechanism

Synthesis from 1 study

How it works

Insulin tells muscle cells to make more energy-producing parts by turning on their genetic instructions, but without enough protein building blocks, the cell can't actually build those parts. So the instructions get louder, but nothing gets made.

Most probable mechanism

In Simple Terms

When insulin levels rise, it signals muscle cells to turn on genes that help make energy-producing parts inside the cell. But if there aren't enough building blocks from protein (amino acids) available, the cell can't actually build those parts, even though the instructions are active. So the genes get turned up, but nothing gets made.

Causal chain

Insulin binds to its receptor on skeletal muscle cells, activating the PI3K-Akt signaling pathway

Verified by multiple studies

which leads to

Activated Akt promotes nuclear translocation of transcription factors that upregulate expression of mitochondrial genes including PGC-1α, NRF1, and COX III

Verified by multiple studies

which leads to

Low availability of essential amino acids, particularly leucine, prevents activation of the mTORC1 complex despite upstream Akt signaling

Verified by multiple studies

which leads to

Inactive mTORC1 fails to phosphorylate downstream translational regulators p70S6K and 4EBP1, blocking initiation of protein synthesis

Verified by multiple studies

which leads to

Increased mRNA levels of mitochondrial genes are not translated into new mitochondrial proteins, resulting in no increase in mitochondrial enzyme activity or ATP production

Verified by multiple studies

Evidence from Studies

Supporting (0)

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No supporting evidence found

Contradicting (1)

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Insulin fails to enhance mTOR phosphorylation, mitochondrial protein synthesis, and ATP production in human skeletal muscle without amino acid replacement.

Randomized Controlled Trial

Human

2012 Nov 1

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Source Study

Insulin fails to enhance mTOR phosphorylation, mitochondrial protein synthesis, and ATP production in human skeletal muscle without amino acid replacement.

Score: 54

DOI: 10.1152/ajpendo.00067.2012

Similar Assertions

When insulin is infused into healthy young adults without providing amino acids, the levels of key amino acids in the blood drop by 40–50% within 7 hours, and this is accompanied by a decrease in muscle protein synthesis and no activation of the mTOR signaling pathway.

78%

In healthy young adults, prolonged high insulin levels without accompanying amino acids reduce the rate of muscle protein synthesis by 20-30% during the final five hours of insulin infusion, even though genes related to mitochondrial function are more active, showing that amino acids are required for insulin to promote muscle protein synthesis.

72%

In healthy young adults, insulin alone cannot trigger key cellular processes for building proteins in muscle unless amino acids are also present, even though insulin still activates its initial signaling step.

71%