Thanks.
It had crossed my mind with looking it up, but I could not understand why anyone would just want to say "hello" in a post, so wondered if the letters stood for anything (?) :)
This sounds like an insulin utilization syndrome. In this case an HBA1C probably won't provide the answer, although it is a good idea to get one. You require an old-fashioned glucose test, or, alternatively what is called the insulin-clamp procedure. High glucose levels after eating produce sleepiness.
I would suggest that you make an appointment to see your doctor and ask if you can have a glucose intolerance test and do a HBA1C blood test. a HBA1C blood test will show the average glucose levels in the blood stream over a period of approximately 3 months.
It may be that you have an insulin intolerance. This means that your pancreas is producing insulin, but this is not being used adequately by your body.
Tiredness after eating food can be due to your sugar levels getting too high and this will cause tiredness.
You may be better eating small quantities more often rather than have a large meal all in one go.
It is also a good idea to get checked out.
You can have blood sugar reactions without being a diabetic. Some people are more sensitive than others. Not to say that's what it is for sure, but it still could be blood sugar. Could also be poor nutrition -- we don't know what you're eating, how long between meals, etc.
Could be an allergy to what you are eating. You say you were tested for diabetes? Well, sometimes low blood sugar can cause the sleepiness after eating, have you had a glucose tolerance test performed?