Why Do I Get Tired After Eating A Lot?

It has more to do with insulin, and blood sugars. High blood glucose levels, can switch off the brain cells{orexin neurons} that normally keep us awake and alert.
I believe it occurs in all mammals.

 

Eat thanksgiving meal, get dozy. It's probably a good thing that male African lions always feed first. They get fat and dozy and forget to kill the cubs.

 

I've heard that it is low glucose levels, not high ones that are responsible. After we eat, our blood glucose levels are elevated causing the release of insulin. Sometimes, if the blood glucose levels are high enough, the body will overcompensate with the insulin resulting in a period of low blood sugar after the insulin has done its work. It's this low glucose period that causes the "food coma."

 

http://www.jneurosci.org/cgi/content/short/24/46/10493

Here is some interesting reading.

 

The fancy name is "Postprandial somnolence". What happens is that when you eat food high in sugar and carbohydrates (which are converted into sugar), your blood glucose levels rise. This causes the body to respond with insulin production, which takes the sugar and amino acids out of your blood.

What happens is that insulin does not have an effect on the amino acid tryptophan, which relative levels in the blood will rise. This causes the neural amino acid transport to shift to transport of tryptophan to the brain, the brain responds in making serotonin (causing the happy feeling), which can be metabolized into melatonin (which regulates circadian rhythm).

Article http://wurtmanlab.mit.edu/publications/pdf/178.pdf" [Broken]

 

Monique when you say insulin increases amino acid uptake, are you talking about muscle cells where gluconeogenesis can not occur?

 

No, I'm talking about the cellular uptake of amino acids from the blood, so that they can be used for protein synthesis: http://books.google.com/books?id=4I...v=onepage&q=insulin amino acid uptake&f=false

 

So eating sugar actually makes one feel sleepy rather than giving a "boost up"?
Don't sportsmen eat sugar while in a prolonged effort? Before a marathon I can understand eating carbohydrate that will later be converted in sugar... but during the run, eating (or drinking) sugar will actually makes the runner sleepy? I just want to be sure I'm not misunderstanding.

 

I realize that this is very late but I'll post the answer anyway...

When sportsmen consume sugar during exercise the system is able to absorb the sugar without the need to balance it. This is because there is a need for it. They will take it during or post exercise only and never pre because before exercise insulin is produced by the body which reacts in the way outlined above (removing many amino acids allowing tryptophan to predominate and later causing melatonin in the brain) and also other unwanted effects.