By Dr. Mallika Marshall

BOSTON (CBS) – The average American will consume 4,500 calories during a typical Thanksgiving and while we say it’s only one day a year, what is happening to our bodies with all of that stuffing? Dr. Mallika Marshall explains.

We’ve all experienced that food coma after indulging on Thanksgiving but what’s really going on to make you feel so sluggish and yet so satisfied? Yahoo! health broke it down by body system, beginning with your brain.

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Psychologists say your mindset before dinner can affect how much you eat. Family stress, like having to sit next to crazy Uncle Ned or having to explain why you’re not married yet, can make you eat (and drink) more.

And once you start to eat, the levels of the feel-good hormone serotonin rise in your brain, making you feel tired and perhaps less mindful of what you’re shoveling into your mouth.

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Whenever you eat, your stomach expands, which typically tells your brain that you’re full, but because you tend to keep eating because it’s Thanksgiving, those signals are overridden and your stomach continues to stretch.

And as for your liver, when you drink alcohol, your liver sees it as a toxin and starts to break it down, but it can only process one drink an hour.

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So those glasses of wine and spiked egg nog can add up quickly.

Dr. Mallika Marshall