It shuts off the neurotransmitters in response to leptin, a hormone released by fat cells.

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Too-high stress hormone levels are directly linked to gastrointestinal problems, lowered immune response, anxiety disorders and depression.

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The body's response to prolonged periods of stress is to secrete increasing amounts of cortisol, a hormone that marshals resources to cope with crises.

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They picked a hormone called glucagon-like peptide-1 (GLP-1) that is made by intestinal cells in response to sugar and fat.

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