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Seeing and smelling food prepares the mouse liver for digestion -- ScienceDaily

A previous study published in Cell in 2015 by another team of researchers found that sensory perception of food by lab mice was enough to trigger the neural pathways normally fueled by eating. Specifically, perceiving food inhibited AgRP neurons, which stimulate appetite, and activated POMC neurons, which induce satiety and suppress eating. The new study built on that research, focusing on how the changes in these neural pathways sent signals that affected metabolic activities in the liver. Here, the researchers found that within five minutes of lab mice perceiving food, the changes in POMC neuron activity were enough to induce a rapid signaling cascade that activated the mTOR and xbp1 signaling pathways. These pathways are normally activated when the liver takes up amino acids from digested food and help increase the protein folding capacity of the endoplasmic reticulum (ER), which assembles proteins from the amino acids found in food.