Fainting after eating?

Yes, my young friend. It's MORE LIKELY to be Reactive Hypoglycemia.

This occurs when your pancreas 'overproduces' insulin in response to the release of sugar (glucose) from the breakdown of carbohydrates during the digestive process.

You WILL, of course, need to see your doctor with regards to getting him/her to refer you for an OGTT (Oral Glucose Tolerance Test), which would either confirm, or refute, that this is what's going on.

Normally, Reactive Hypoglycemia will show its symptoms between 1.5 hours and 2 hours after eating.

The bad news is, there is no "magic pill" that will solve this for you.

IF it is Reactive Hypoglycemia, you will be requested to eat smaller, but more frequent meals, throughout the day ... eating every 2 or 3 hours ..., to eat fewer carbohydrates, but to also to incorporate more fat and/or protein in your meals. (Fats and proteins slow down the absorption of glucose into the bloodstream, which means that your pancreas shouldn't produce so much insulin in response, thereby causing you to NOT experience the symptoms that you are currently experiencing.)

I guess climate also is one of the cause。。。

Guess you need to see a doctor