Ghrelin

Citing a study in the Annals of Internal Medicine, the speaker reports that two nights of 4-hour sleep caused Leptin (satiety hormone) to drop by 18% and Ghrelin (hunger hormone) to rise by 28%. This hormonal shift increased hunger ratings by 24% and cravings for high-carb foods by 30-45%.

The speaker explains that the hunger hormone Ghrelin does not directly cause eating but activates a separate set of brain cells running on the neuropeptide Orexin (transcript: 'ereexen'). These Orexin neurons are the actual drivers of the drive to eat. The mechanism is described as a signaling circuit where Ghrelin flips on Orexin, which then triggers feeding behavior.

The speaker explains that the pituitary gland releases growth hormone in pulses, driven by two independent signals: GHRH and a ghrelin-mediated pathway. By targeting these two separate receptor systems, peptides can work synergistically to double GH output compared to single-pathway stimulation.

Ghrelin, the hunger peptide hormone, exerts its appetite-stimulating effects by activating orexigenic neuropeptide Y (NPY) neurons located in the arcuate nucleus of the hypothalamus. This represents the mechanistic pathway through which ghrelin drives hunger signaling centrally. No dosages, study citations, or specific evidence sources are provided in the transcript.

Ketone esters have been shown to reduce circulating levels of ghrelin, the primary hunger-signaling peptide hormone. By suppressing ghrelin, ketones may blunt appetite drive. No specific dosage, study citation, or evidence tier is explicitly stated by the speaker — the claim is presented as established fact without referencing a specific trial or study design.