Is Bread a Fast or Slow Digesting Carb? (A Dietitian Answers)

If you eat bread regularly, you might wonder how fast the body digests it.

White bread or bread like a French baguette is fast-digesting. This is because these options are lower in fiber and fat, and the body absorbs them faster. However, if you choose options like oat bran or mixed grain bread, they have higher fiber and protein content making them a slower-digesting food.

Understanding bread’s digestion speed can help determine the best time to consume it. You might want to have it as a carb source before or after a workout, before long fasting hours, or simply as an afternoon snack to hold you over until dinner. 

Using the Glycemic Index To Determine How Quickly Bread Digests

One way we can determine how fast or slow a food digests is by using the glycemic index. 

The glycemic index (GI) is a measurement of how fast a food can raise sugar levels. Of the three macronutrients (protein, fats, and carbohydrates), carbs are the easiest to digest. And since the glycemic index only measures how fast a food raises sugar levels, it mostly measures starchy foods (or those with sugar content). 

However, the glycemic index can change if a carb is mixed with other macronutrients.

A food with a low protein, fiber, or fat content can have faster absorption, meaning it has a higher glycemic index. On the other hand, a food with a low protein, fiber, or fat content can have slower absorption, meaning it has a lower glycemic index.

The glycemic index uses a scale of 1-100:

  • Low: 1-55
  • Medium: 56-69
  • High: > 70

The higher the number of a food item, the higher the sugar response, meaning that food has a faster absorption. 

How Long Does It Take Bread To Digest?

How long it takes bread to digest depends on the type of bread and the addition of other foods. Based on these factors, it can take between 30 minutes and several hours for bread to digest.

White bread has a faster absorption since it has a lower protein and fiber content. Your body can start to digest it in less than an hour if you eat it on its own.

On the other hand, whole-grain bread that is higher in fiber and protein can take two to three hours to get digest.

If you eat bread with other fat or protein sources, it will also take longer to digest because fat and protein are slower digesting.

Is Bread a Complex or Simple Carb?

White bread is a simple carb, and whole-grain bread is a complex carb. But to understand why different types of bread fall into different categories, we need to know the definitions of simple and complex carbs and how manufacturing processes affect a food’s classification.

Simple carbs are short molecules of sugars. You might find them alone (only one sugar molecule) or in pairs. Since they come in smaller molecules, the body doesn’t have to do too much to process them, meaning they are easily absorbed. 

You can find natural sources of simple carbs like sugars, honey, fruit, and lactose (milk). However, there are also processed simple carbs. These happen when you take whole grains and process them until you remove most of the fiber (which is the case with white bread), making them easier to digest. 

On the other hand, complex carbs are long chains of sugars. Thus, the body needs to cut each sugar to digest them, making them absorb slower. These tend to be higher in fiber, vitamins, and minerals (which is the case with whole-grain bread).

Types of Bread: Ranking From Fastest To Slowest Digesting

As discussed, there are different types of bread, meaning they can have different digestion speeds. It all depends on their fiber, protein, and fat content. 

So, to help us determine which is the fastest and slowest type of bread to digest, let’s take a closer look at the glycemic index of different types of bread.

Type of breadGlycemic Index (GI)
French baguette95
Gluten-free bread79
White bread70
White bagel69
Hamburger bun61
Pumpernickel bread56
Mixed grain bread52
Oat bran bread41

French baguette has the highest glycemic index, meaning it has the fastest absorption compared to other types of bread.

On the other hand, oat bran bread has the lowest glycemic index, meaning it has the slowest absorption. 

So, why is there a massive difference between bread? 

It depends on the processing and added ingredients. The more processing a flour undergoes, the less fiber it has, and the higher it will be on the glycemic index.

Also, adding nuts, seeds, and any other type of fat can help make the absorption slower. 

Benefits and Drawbacks of Eating Fast-Digesting Carbs Like White Bread


1. They Give You Immediate Energy 

One of the benefits of white bread is that it can give you immediate energy.

There are several reasons why this is advantageous. 

First, it can be a great snack to have before exercise. Since it doesn’t take long to digest, it gives you immediate energy to get through an arduous workout without producing digestive symptoms like bloating, gas, and stomach cramps that can affect your performance. 

Also, if you feel light-headed, meaning you have a sudden sugar drop, white bread can help you regain your strength. 

2. They Are Easier To Digest

For people with Chron’s disease or irritable bowel syndrome (IBS), low-fiber foods like white bread can be beneficial in avoiding any flare-ups.

They allow you to reach your caloric requirements without causing any symptoms. 

3. They Help You Reach a Caloric Surplus 

Finally, fast-digesting foods like white bread are beneficial because they allow you to easily increase your calories if you’re trying to build muscle. 

For those in a caloric surplus (eating more calories than your body needs to maintain weight), adding fast-digesting foods allows you to eat more without feeling too stuffed.


1. They Are Not Filling 

As mentioned, fast-digesting carbs are low in fiber. Fiber can help increase your fullness levels. But since white bread is low in fiber, it doesn’t keep you full for long. This is a disadvantage for those trying to lose weight.

While you can include white bread on a weight loss journey, the portion size you need to stay within your calorie margin might be too low.

On top of that, it might leave you feeling hungry since it doesn’t fill you up much. This can result in more snacking and wanting to eat larger portions at meals, affecting your goals. 

2. They Can Spike Your Sugar Levels

Another drawback of fast-digesting foods like white bread is that they can spike your sugar levels. For people with diabetes, this is a serious concern since it might cause hyperglycemia

If you’re not diabetic, unstable sugar levels can lead to cravings and fluctuations in your energy levels. 

3. They Are Not Nutritious 

Not all fast-digesting foods are low in nutrients. Options like fruit and some dairy products are high in nutrients. However, that is not the case for white bread. Since it undergoes a lot of processing, most of the fiber and nutrients are lost. 

So, in the end, you consume calories but don’t get a lot of nutrients. If you don’t balance the rest of your meals by including high-nutrient foods like vegetables, you might become deficient in key nutrients.

Benefits and Drawbacks of Eating Slow-Digesting Carbs Like Whole-Grain Bread

Pros vs Cons of eating slow-digesting carbs like whole-grain bread


1. They Provide Long-Term Energy

One of the biggest benefits of whole-grain bread is it provides long-term energy. Since it takes longer to digest, it won’t cause a massive sugar spike.

So, instead of giving you a sugar rush, it creates more stable energy levels to prevent you from feeling fatigued. 

For people who need to have more stable glucose levels, like those with diabetes, whole-grain bread is a better option. 

2. They Increase Fullness Levels

Fiber cannot be fully digested. As a result, it stays longer in the stomach and increases fullness levels. This can be a great ally in weight management. 

When you feel fuller, you are less likely to snack and more likely to have smaller portion sizes at your meals. This makes it easier to be in a caloric deficit (eating fewer calories than your body needs to maintain weight), helping you achieve weight loss. 


1. They Won’t Give You Fast Energy

If you want immediate energy before a workout, whole-grain bread is not the way to go.

Since whole-grain takes longer to digest, it can lead to feeling sluggish, bloated, or gassy before hitting the gym. 

2. They Might Cause Digestive Problems

Finally, since whole-grain bread is higher in fiber, it might cause stomach problems. If you are not used to consuming a lot of fiber, you may experience symptoms such as bloating, gas, stomach cramps, and diarrhea. 

If this is the case, make sure to add small quantities of whole-grain bread until your body gets used to the fiber intake. 

When Should You Eat Bread? 

When you should consume bread depends on the type of bread you eat.

For example, for quick energy before a workout, you might want to include white bread to boost your energy levels without giving you digestive symptoms.

On the other hand, for those with long fasting hours due to intermittent fasting or a busy work schedule, whole-grain bread is a better option since your body digests it more slowly. This allows you to stay fuller for longer and endure the fasting hours. 

Also, slower-digesting bread is a great snack before bedtime. It can prevent you from waking up hungry in the middle of the night to search for something to eat. 

Factors That Affect the Digestion of Bread 

1. Processing 

As discussed, you need to remove most (if not all) of the fiber to create white bread. This creates a more palatable option.

However, removing the fiber makes digestion faster. That is why white bread (which is more processed) has faster digestion than whole-grain bread (which is not as processed). 

2. Added Foods and Toppings

The toppings and ingredients you add to bread can also affect the digestion speed. Foods higher in fiber and fat, like nuts, seeds, and butter, can take longer to digest, reducing the digestion speed. 

For example, plain white bread with nothing added to it has faster digestion than white bread with chia seeds.

Also, including foods like non-starchy vegetables (tomatoes, cucumbers, lettuce, kale, mushrooms), healthy fats (avocado, peanut butter, and mayo), and protein (chicken, cheese, and meat) helps reduce the digestion of bread.

About The Author

Brenda Peralta

Brenda Peralta is a Registered Dietitian and certified sports nutritionist.  In addition to being an author for, she fact checks the hundreds of articles published across the website to ensure accuracy and consistency of information.

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