Three years ago I began experiencing episodes of low blood sugar and was diagnosed with severe hypoglycemia.

Hypoglycemia is often experienced after gastric bypass surgery, a small percentage of rare cases may become severe.

Here are some things that I have found that work for me.

I eat 4 to 5 small meals each day which includes a mid-afternoon meal in order to help keep my blood sugar and insulin levels steady between lunch and dinner.  I make sure I eat before going on a walk, a trip to the gym, or even shopping or housework. 

I have a very small "snack meal" after dinner before bedtime. My "snack" meals are very small (healthy) meals, very similar to what I eat for lunch, only smaller portions. I keep a fairly close food journal on how much I'm eating throughout the day. I often have to add a snack in the morning on the days I am more active or go to the gym.   

I never eat carbs on a empty stomach, as it causes blood sugar levels to raise and lower too fast. I always eat them with a protein. I might add a tiny meal such as a few ounces of chicken and 1/3 cup black beans or chicken and 1/3 cup of sweet potato.

Low glycemic index foods such as black beans are slowly digested, (as is the sweet potato) raising the blood sugar at a slower pace. The beans and chicken work together to slow the digestion down. Eating these combinations of foods together is called the glycemic load. 

My hypoglycemia is been very hard to control with diet alone, but these things do help. (At this time I am taking a prescription drug which helps to lessen my episodes, but I am continually trying different food options to see what works and to improve my success.)

Everyone reacts differently, and must find what works best individually. But there are a few tips that might save you from getting into trouble. 

• Keep a close watch on your blood sugar level. 
• Do NOT skip meals (skipping meals slows your metabolism)
• Eat small amounts of carbs (around 15 grams per meal) Never on an empty stomach. Avoid foods with sugar and high sugar fruits and don't eat low sugar fruit on an empty stomach.
• Always eat protein first.
• Avoid starchy veggies, pasta, bread, cereals, white (enriched), refined flours, and sugars. (this includes milk, which is high in sugar)
• Avoid artificial sweeteners, (which stimulates insulin and enhances insulin-resistance.
• Eat whole food items and avoid processed food items. 
• Eat every 3-4 hours.
• Fiber slows down digestion, so add fiber by eating foods with the highest fiber content possible, anything 3 or above is good.
• Exercise in small intervals, pacing what works for you.

It may require trial and error to find what works.  

This article copied from wikipedia on Gastric dumping syndrome, or rapid gastric emptying is a condition where ingested foods bypass the stomach too rapidly and enter the small intestine largely undigested. It happens when the upper end of the small intestine, the duodenum, expands too quickly due to the presence of hyperosmolar (substances with increased osmolarity) food from the stomach.

"Early" dumping begins concurrently or immediately succeeding a meal. Symptoms of early dumping include nausea, vomiting, bloating, cramping, diarrhea, dizziness and fatigue. "Late" dumping happens 1 to 3 hours after eating. Symptoms of late dumping include weakness, sweating, and dizziness. Many people have both types. The syndrome is most often associated with gastric surgery.

It is speculated that "early" dumping is associated with difficulty digesting fats while "late" dumping is associated with carbohydrates.^{[citation needed]}

Rapid loading of the small intestine with hypertonic stomach contents can lead to rapid entry of water into the intestinal lumen. Osmotic diarrhea, distension of the small bowel (leading to crampy abdominal pain), and hypovolemia can result.

In addition, people with this syndrome often suffer from low blood sugar, or hypoglycemia, because the rapid "dumping" of food triggers the pancreas to release excessive amounts of insulin into the bloodstream. This type of hypoglycemia is referred to as "alimentary hypoglycemia".

Diagnosis

Physicians diagnose dumping syndrome primarily on the basis of symptoms in patients who have had gastric surgery. Tests may be needed to exclude other conditions that have similar symptoms. Two ways of determining if a patient has dumping syndrome include Barium fluoroscopy and radionuclide scintigraphy.

In the first procedure, a contrast of barium-labeled medium is ingested, and x-ray images are taken; early dumping can be easily recognized by premature emptying of the contrastmedium from the stomach.

The second method, scintigraphy (or radionuclide scanning), involves a similar procedure in which a labeled medium containing ^99mTc (or other radionuclide) colloid or chelate is ingested. The ^99mTc isotope decays in the stomach, and the gamma photons emitted are detected by a gamma camera; the radioactivity of the area of interest (the stomach) can then be plotted against time on a graph. Patients with dumping syndrome generally exhibit steep drops in their activity plots, corresponding to abnormally rapid emptying of gastric contents into theduodenum.

Treatment

Dumping syndrome is largely avoidable by avoiding certain foods that are likely to cause it, therefore having a balanced diet is important. Treatment includes changes in eating habits and medication. People who have gastric dumping syndrome need to eat several small meals a day that are low in carbohydrates, avoiding simple sugars, and should drink liquids between meals, not with them. Fibers delay gastric emptying and reduce insulin peaks. People with severe cases take medicine such as octreotide, cholestyramine or proton pump inhibitors(such as pantoprazole) to slow their digestion. Doctors may also recommend surgery. Surgical intervention may include conversion of a Billroth II to a Roux-en Y gastrojejunostomy.

Most of the text of this article is taken from http://digestive.niddk.nih.gov/ddiseases/pubs/rapidgastricemptying/index.htm