If you've ever eaten dessert on an empty stomach, chances are you've experienced what's known as a blood sugar "crash." The cells in your body don't get enough energy, so you often end up feeling tired, irritable, dizzy, hungry and you may even experience shakiness or light-headedness. 

This occurs because your body responds to the sudden influx of sugar in your system by releasing too much of the hormone insulin, which causes your blood sugar, also known as glucose, to plummet below normal levels. Though this occurrence isn't usually anything to be overly concerned about if it doesn't happen often, it's a good reminder that what we eat affects how we feel. 

Who needs to lower blood sugar? 

Some people need to monitor their blood sugar levels a lot more than others. People with diabetes, for instance, have to constantly check their blood sugar levels and need to be especially mindful of what they eat. "People with type 2 diabetes have insulin resistance, which means their tissues don’t respond well to insulin," explains Dr. Dariush Mozaffarian, a cardiologist and professor of nutrition and medicine at Tufts University. Because of this, he says, "blood glucose levels can rise very high while the tissues starve from lack of energy." 

People without diabetes may also want to prevent their blood sugar levels from spiking too often. "Occasional glucose spikes are not damaging long-term, especially when the body is young and resilient," says David Sinclair, professor of genetics and a longevity researcher at Harvard Medical School. "However, constant spiking from eating foods with excess sugar can cause brain fog and hunger pains when sugar levels plummet." 

Along with these short-term effects, regularly eating poorly and not allowing the body enough time to absorb glucose between meals can cause further issues to "accumulate over time," says Mozaffarian. These can include cardiovascular and kidney-related problems. 

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What should your blood sugar be 2 hours after eating?

Because the food we eat is broken down into blood sugar, it's normal to experience a blood sugar boost, sometimes called a spike, for a period of time following a meal. This is a sign food is being converted into energy and that the pancreas is doing its job. One's blood sugar will increase temporarily before it begins dropping again. Before a meal, blood sugar is usually in the range of 80 to 130 milligrams (mg) per deciliter (dL), but the U.S. Centers for Disease Control and Prevention (CDC) notes that it's okay if this digestion-related boost causes one's blood sugar to be as high as 180 mg/dL about two hours after a meal. 

After that time, your blood sugar should be dropping as the insulin in your body helps the glucose get absorbed. If your blood sugar doesn't drop, however, you might have diabetes or prediabetes. 

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How to lower blood sugar

People with diabetes or prediabetes need to work especially hard to manage their blood sugar levels. They do so primarily by injecting insulin and watching what they eat. 

People without diabetes can similarly watch what they eat and do other things to avoid the effects of having too much sugar in their bloodstream. Healthy weight management and getting regular exercise have proven to maximize insulin sensitivity and keep blood sugar levels in a normal range. 

It's also important to minimize the consumption of ultra-processed foods, refined carbs such as pasta, white rice, and white bread and to avoid foods with too many added sugars. Along with avoiding the wrong foods, it's critical to also eat foods known to help with healthy blood sugar management. "Eat more fiber-rich foods like fruits, vegetables, nuts and seeds," advises Mozaffarian. He also recommends "eating more healthy fats, proteins and carbs from foods like plant oils, fish and yogurt."