Lightheaded and Shaky After Eating Sugar

While you might be tempted to grab a sweetened beverage or sugary snack for energy, several hours later you may feel worse. Simple sugars cause spikes in blood sugar, resulting in feeling lightheaded or weak. Understanding how the glycemic index and glycemic load affect blood sugar can help you select foods that provide energy with no crash.

Glucose is the primary source of energy for brain cells or neurons. Neurons require twice as much energy as other cells. Simple carbohydrates, like sugar, corn syrup, and fruit juices are easily broken apart and absorbed into the bloodstream. In response to the sudden increase in blood sugar, the pancreas begins secreting insulin, a hormone that allows cells to use glucose. The spike in insulin causes glucose to be rapidly absorbed by cells, resulting in a drop in glucose. Neurons no longer have their energy source readily available, which causes you to feel lightheaded, shaky, spaced-out and weak.

Long-term, chronic consumption of sugar and sweetened beverages may increase Type 2 diabetes risk. A study published in "The Journal of Nutrition" in 2007 collected dietary history of more than 4,000 men and women aged 40 to 60. Twelve years later, they followed up with subjects to see if anyone had developed Type 2 diabetes. They found a positive relationship between those who reported eating more simple sugars and developing the disease. The researchers suspect that the simple sugars may disrupt normal insulin metabolism. Simple sugars may also cause weight gain by providing additional calories.

The ranking of carbohydrates in the Glycemic Index depends on how much they raise blood sugar. The scale ranges from 0 to 100. The higher the score, the faster it is digested and more likely it is to raise blood sugar. Foods ranked 55 or lower are low glycemic foods, while foods ranked 70 or above are considered high glycemic foods. Several factors affect a food's glycemic index. Processed, milled, and refined grains, finely ground grain, ripe fruits and vegetables, low fiber foods, foods with low fat or acid content all tend to have a higher glycemic index.

The glycemic load indicates how much digestible carbohydrate a particular food yields. To calculate glycemic load, multiply glycemic index by grams of carbohydrates and divide by 100. A food with a glycemic load of 20 or more is high, 11 to 19 is medium, and 10 or less is low. Low glycemic load foods include fruits, beans, nuts, and bran cereals. Medium glycemic load foods include oatmeal, brown rice and whole grain breads. High glycemic load foods include baked potatoes, candy bars, sugar-sweetened beverages, and white rice. To help combat fluctuations in blood sugar, select a low glycemic load food to release glucose into the bloodstream gradually, avoiding spikes and drops.