Bagels are a beloved American breakfast staple—but they’re also notoriously high in simple carbohydrates, which break down easily into glucose and are rapidly absorbed into the bloodstream. That might leave you wondering how eating them on a routine basis could affect your blood sugar levels.
While a plain, medium-sized (3 ½–4 inch) bagel contains 1.7 grams of fat and 11 grams of protein, the majority of its calories—78%—come from its 56 grams of carbohydrates. Whole wheat bagels have slightly fewer carbs (around 51 grams) and offer more fiber and additional nutrients, such as iron, but they’re still relatively high in carbohydrates.
Here’s how a bagel compares to the carb content of other common breakfast foods:
- One cup of cooked oatmeal: 27 grams
- Two slices of white bread: 28 grams
- A cup of raisin bran cereal: 47 grams
- A Pop-Tart: 39 grams
Because bagels are high in simple carbohydrates that the body processes quickly into glucose, eating one on its own will likely cause a quick spike in blood sugar, said Jamie Mok, MS, RDN, RYT, National Media Spokesperson for the Academy of Nutrition and Dietetics.
Case in point: The glycemic index—a measure of how quickly food raises blood sugar—of a medium-sized plain bagel is 70, a high score.
In the right context—such as before a strenuous workout, when you need a quick burst of energy—that surge can be helpful. However, “this rapid rise and fall in blood sugar can sometimes lead to a ‘crash,’ leaving a person feeling tired, irritable, and hungrier soon after,” Violeta Nieves Morris, MS, RDN, a dietitian who specializes in prediabetes, diabetes, and weight management, told Health.
That said, in healthy, active people, a post-bagel blood sugar spike is usually small, according to Andres Splenser, MD, an endocrinologist with Memorial Hermann Medical Center in Houston.
But for people with insulin resistance, obesity, or diabetes, the spike—and subsequent crash—can be much more pronounced, since the body has a harder time moving excess glucose from the bloodstream into cells for energy.
In this population, “eating refined carbohydrates or processed foods like bagels or cereals can cause a sugar spike where blood sugars may go above the normal range,” he told Health. This often triggers an increased insulin response, leading to an even more dramatic energy rollercoaster.
When it comes to eating bagels regularly, the effects on blood sugar depend on the individual and their overall health status, experts said.
For example, Mok explained that a generally healthy marathon runner would likely use the bagel’s carbohydrates for immediate energy, “so eating one daily may pose little risk.”
But that’s not the case for everyone. For less active people—and especially those with type 2 diabetes—a daily bagel could contribute to higher daily blood sugar surges, which could have more detrimental effects over time.
“Repeated and frequent large spikes in sugar are worrisome,” Splenser said. They “may increase oxidative stress and inflammation, stress the insulin-producing cells in the pancreas, and increase the risk of other medical conditions, like fatty liver and metabolic dysfunction.”
Your overall metabolic health isn’t the only piece of the glycemic puzzle. Other factors matter, too. When eating a bagel, you can offset a potential rise in blood sugar by taking the following steps:
- Choosing a smaller portion: The larger the bagel, the more simple carbohydrates hitting your bloodstream.
- Opting for whole wheat: Bagels made with whole grains like whole wheat or oats provide more fiber, which can slow sugar absorption, according to Splenser.
- Eating your bagel in the morning: Studies show that insulin sensitivity and glucose tolerance peak in the morning, leading to lower blood sugar spikes from carbohydrate-rich foods.
- Paying attention to added sugars: Bagels made with added sugar increase the likelihood of a spike-and-crash effect.
- Pairing your bagel with certain foods: Eating a bagel with protein, healthy fats, or fiber can temper the absorption of its simple carbs. Good options include eggs, hummus, and avocado.
Bagels contain simple carbohydrates, which break down easily into glucose and are rapidly digested. While most people may experience only a small rise in blood sugar, it can be more pronounced in individuals with obesity or diabetes.
Over time, regularly consuming large amounts of bagels could contribute to inflammation and metabolic dysfunction. You can help minimize a potential blood sugar spike by choosing a smaller portion and pairing your bagel with protein, healthy fats, or fiber.
