Blood sugar levels refer to the concentration of glucose in your blood. Glucose is the body’s preferred source of fuel, therefore it’s important to maintain steady blood sugar levels to provide energy to your cells. 

Chronically high blood sugar levels can lead to diabetes, heart disease, or metabolic syndrome, therefore it’s important to maintain your blood sugar levels. Here is an overview of how your body maintains its blood sugar levels and tips for keeping your blood sugar levels steady.   


How Does Blood Sugar Change After a Meal?

When you eat carbohydrates they are broken down into monosaccharides including glucose molecules that are absorbed into your bloodstream and cause an increase in blood sugar levels.   

As blood sugar levels increase, the pancreas begins to secrete the hormone insulin into the blood. Insulin is like a lock and key that opens the cells to allow glucose in. When insulin binds to insulin receptors located on the surface of the cell, glucose can enter the cell to be converted to energy or stored as fat or glycogen for later use. 

Ideally, you want a slow and steady increase in blood sugar so the body can respond with a slow and steady amount of insulin to move sugar out of the blood and into the cells. As sugar moves into the cells, insulin levels slowly come down. 

To create that slow and steady increase in blood sugar, you need to eat some fiber, protein, or fat with carbohydrates to slow down the digestion and absorption of the carbohydrates. 

Tip: Eat meals that contain fiber, protein, and/or fat to slow the absorption of glucose into the blood and prevent spikes in blood sugar levels. 


What Happens When Blood Sugar Spikes

When you eat a meal that’s high in refined grains, white flour, or added sugar, the carbohydrates in those foods will be quickly digested and absorbed into the bloodstream, causing a spike in blood sugar. 

If blood sugar levels increase too quickly the pancreas will respond by releasing a ton of insulin to quickly move the excess glucose out of the blood and into the cells. Due to this high level of insulin, glucose with rapidly move out of the blood causing blood sugar levels to plummet. Low blood sugar is known as hypoglycemia. This quick decrease in blood sugar levels is sometimes referred to as the “sugar crash” that people experience after eating foods high in sugar. As your blood sugar quickly decreases you’ll start to feel lethargic, irritable, and may crave sugar as your body tries to prompt you to each more glucose to bring your blood sugar levels back to normal. 

When your blood sugar levels become too low your body will start sending hunger signals so you consume carbohydrates to replenish glucose levels in the blood. This is why you may feel hungry shortly after eating a meal that contains a lot of refined carbohydrates or sugar


Insulin Resistance and Diabetes

When blood sugar levels are consistently high, insulin is continuously being released into the blood to lower your blood sugar. If this happens too often the insulin receptors on your cells get fatigued and stop responding to insulin (i.e., insulin resistance), which means sugar can’t move out of the blood and into your cells.

Type 2 diabetes occurs where your body stops responding to insulin or your pancreas can no longer produce enough insulin to regulate consistently high blood sugar levels.

Type 1 diabetes is not caused by high blood sugar. It’s an autoimmune disorder where your body attacks the beta cells in your pancreas that produce insulin. Eventually, your body loses the ability to produce insulin and you must use insulin injections to maintain blood sugar levels. 


How to Prevent Blood Sugar Spikes and Crashes

  • Moderate physical activity: at least 30 minutes most days helps to reduce insulin resistance
  • Aim to consume at least 25 grams of fiber per day
  • Limit intake of sugar-sweetened beverages
  • Replace saturated fat with monounsaturated fats (olive oil, nuts, avocado) to reduce insulin resistance
  • Limit alcohol intake to 1-2 drinks per day
  • Mediterranean-style eating pattern that focuses on low glycemic index foods
  • Strength training, which helps your cells better utilize glucose
  • Reduce stress since cortisol promotes the release of glucose from the liver, which can increase blood sugar levels
  • Regular meal times


Glycemic Index

The glycemic index of a food is an estimate of how much your blood sugar levels would increase after eating a specific food in comparison to consuming pure glucose. 

Glucose has a glycemic index of 100, which is the reference point for the glycemic index of other foods. 

Let’s say you eat a pear, which has a glycemic index of 38. This means that your blood sugar levels will rise to 38% of the level that would occur if you were to eat pure glucose. 

To prevent large spikes in your blood sugar levels, you want to eat carbohydrates that have a lower glycemic index (≤55). This mainly includes foods high in fiber, such as non-starchy vegetables, fruit, and whole grains. Foods high in fat or protein are also low on the glycemic index. 


More Basic Nutrition Articles

An Introduction to Intuitive Eating

Nutrition 101: What are Macronutrients?

Nutrition 101: What are Probiotics and Prebiotics

Nutrition 101: How Your Digestive System Works

How to Meal Prep: The Steps to Start