One of the reasons that I personally follow a Zero Carb diet (limited to meat, cheese, eggs and butter) is “The Blood Sugar Roller Coaster”  Here is what that is all about.

There is a condition common to people who eat a carbohydrate based diet that I like to call “The Blood Sugar Roller Coaster” and scientists call Reflex Hypoglycemia.  

Insulin is not just released when you eat carbohydrate or protein.  If you  just watch someone eat cookies or even see a big ad showing them your body will release insulin.  Insulin is always going to make your sugar levels go down.  There are 2 problems that often occur with insulin releases of any kind.  

The first is that in the body there are cells in the duodenum called “enteroendocrine cells” that detect carbohydrates and signal the pancreas to release insulin.  The problem is that they are not very good at judging how much carbohydrate we ate and thus often call for too much insulin.  Refined carbohydrate also raise the blood glucose very fast (whole wheat is a refined carbohydrate and raises it very fast, faster than sugar from the sugar bowl).  The pancreas watches for rises in glucose and the faster it is rising, the more insulin it puts out.  Thus you wind up with too much insulin in your system, especially when you eat refined carbohydrates, crashing your blood sugar giving you symptoms like weakness, trembling, headache and you can even pass out in severe cases though this is rare.  The pancreas responds to this by putting out a ton of the hormone glucagon which raises blood glucose by triggering glucose release in the liver.  Adrenaline is also secreted by the adrenal glands to further raise blood sugar and the sugars then go too high triggering more insulin and another crash.  This is the blood sugar roller coaster.  
The other bad thing that can happen is that you look at all the wonderful carbohydrates, smell them, dream about them causing an insulin release then don’t eat anything.  This will also crash your blood sugar and can put you on the roller coaster.