top of page

Your Meals Blog


Does Toasting Bread Really Reduce Carbs? Toast vs Bread on Keto

Updated: May 7, 2022

The ketogenic diet has been increasingly popular in recent years, with millions of people eager for the metabolic benefits it can offer. However, the transition from a carb-rich diet to a low-carb lifestyle can prove very difficult for many. Bread is a staple food for most families as well as a beloved & versatile comfort food. Understandably, bread is a food that many well-intentioned ketoers really struggle to give up.

Of course, on the internet, misinformation about carbs and keto is everywhere. One common suggestion is that toasting bread lowers its carbohydrate content, making it friendlier to low carb diets. But does this actually work? Is there any truth to it, or is it just wishful thinking?

Simply put, toasting does not do much to affect nutrients and macros in white bread, although there might be one advantage gained from toasting. Toasted white bread does have a slightly lower GI, and freezing bread before toasting reduces this further, giving the starches a more tempered effect on blood sugar and insulin production. As insulin suppresses ketone production, this makes toasted bread slightly better than untoasted white bread – but in the end, it doesn’t actually change your carb intake.

How much difference does this make in practice? Does this make it any better to occasionally eat bread on a keto diet? Let’s go into more detail about the health effects of toasting bread, to find out whether it’s a helpful strategy for a ketogenic diet.

How Does Toasting Affect the Nutrients and Macros in Bread?

To discover more about the nutritional effect of toasting bread, we need to look closer at what actually happens when bread is toasted.

Toasting your bread causes a chemical reaction in which some molecules separate, removing water and making the bread much drier. This is really the main change that happens when bread is toasted: some of the water is removed, while calories stay pretty much the same. If you burn your bread to a blackened crisp then yes, you will see a calorie change – but who would want to eat that?

Similarly, toasting bread only has a very minimal effect on the carbohydrate content. Unfortunately, if you’re on a strict keto diet, then bread is still something to be avoided, whether it’s toasted or plain. Exceeding your daily carb goals can still kick you out of ketosis either way, so even a one-off indulgence can really sabotage all your hard work.

However, toasted bread can still be a little more forgiving in the carbs department than plain white bread. Toasting bread has been shown to lower its glycaemic index (or GI), meaning the carbohydrates take longer to break down. As the starch is slightly more ‘resistant’ and harder to digest and therefore glucose is released into your bloodstream more slowly. While this still causes your insulin levels to go up – something that suppresses that crucial ketone production – it will not be as dramatic as when you eat untoasted bread.

So, if you are resigned to having a ‘cheat meal’ or you’re stuck on lockdown with nothing else to eat, your indulgent slice of white bread may as well be toasted. It won’t undo the damage to your hard-earned ketosis, but I think you’ll agree that any improvement is better than nothing in this case.

There is also another popular ‘hack’ of sorts to lower the glycaemic index of bread, and we’ll look at that in a moment.

As for those with gluten intolerance, unfortunately you’ll still have to avoid wheat-based bread altogether. Toasting bread does not eliminate or even affect the gluten content in bread.

How Does Freezing Affect the Nutrients and Macros in Bread?

Interestingly, researchers have discovered that if you freeze white bread before eating it (after you defrost it, of course) the glycaemic index goes down by 31 per cent – a pretty significant result. Like toasting, freezing the bread changes the molecular structure of starch to a form that is harder to digest, a more “resistant starch”. Again, the lower the glycaemic index means the more gradual it is for your body to absorb the glucose into your bloodstream.

Therefore, a combination of freezing the bread, defrosting it, and giving it a nice toast before consumption seems to be the best combination for those who still want to have that occasional slice of bread.

It does take a bit of effort and commitment to go through the steps, so if you are on a keto diet and want to keep your carbs to a minimum, you might be better off investing that effort elsewhere. In addition to buying low carb bread, you can try making a keto-friendly microwave bread or cloud bread in less times than it takes to freeze and toast a loaf.

It’s a good idea to stock your freezer with a keto-friendly bread for occasions just like this. If you always have a keto alternative on hand, you’ll be less tempted to cave and tuck into a slice of white bread.

Note that in all of these studies, the tests were carried out on white bread, as it is by far the most widely consumed variety. At the time of writing, the jury is still out as to whether the same results apply to brown or wholemeal bread, given that the level of resistant starches is already higher. However, it’s logical to assume that defrosting then toasting your bread will have some effect on its glycaemic index score, whether it’s white or wholemeal.

Is Toasted Bread Healthier Than Untoasted Bread?

While toasting bread is proven to lower its glycaemic index, giving it a less dramatic effect on blood sugar and insulin levels, there are a few disadvantages of toasting your bread.

Starchy foods like bread naturally contain the amino acid asparagine. When these foods are exposed to high cooking temperatures, a chemical called acrylamide is formed. Unfortunately, studies have demonstrated that high levels of acrylamide are known to cause cancer. While the levels of acrylamide are thankfully low when it comes to untoasted bread, the levels of this chemical are significantly higher when the bread is toasted.

The more the bread is toasted and the darker the colour, the more acrylamide is produced – so if you’re burning your bread to a crisp in an attempt to reduce the calorie count, you’re unfortunately maximising your acrylamide exposure in the process. Whether or not to be concerned about this is a matter of individual perspective – after all, plenty of people cook and brown their foods without concern. But if you really want to identify the healthiest approach, your best bet is to toast bread lightly.

And when it comes to freezing and toasting your bread, it may lower the GI, but, there is also a health disadvantage here. If you suffer from irritable bowel syndrome (IBS), usually manifested in bloating and gas issues after eating, this increase in resistant starch can make it harder on your digestive system.

The more resistant starches are exactly what gives frozen bread its low-GI benefits, but they’re harder to digest for people who suffer from IBS, bringing about the uncomfortable and potentially embarrassing symptoms stated above.

Related Questions

Does the Crust of Bread Have More Carbs?

It’s a common assumption that bread crusts have fewer carbs, or are at least healthier than the soft interior. Scientific results are mixed on this topic, with some studies finding there are health benefits and others coming up negative. Since the crust is nothing more than the outer layer of the dough that is most exposed to the oven’s heat, and it is such a small part of the bread itself, it would be safe to assume that any nutritional benefits would be minimal.

What Is the Healthiest Bread You Can Eat?

A popular ‘healthy’ bread variety is Ezekiel Bread, taken from the Bible verse that mentions how bread was made during ancient Biblical times. It’s made with many whole grains, which are allowed to sprout before they go into the flour mill. Sprouting not only increases the nutrients available in the bread, but it also lowers its glycaemic index. A slice of Ezekiel bread has only 15 grams of carbohydrates, which is fairly high for a keto diet, but for regular health-conscious eaters, is better than other varieties of bread.

Another popular type of bread among the low carb & keto communities is not technically bread at all, but a creative protein-rich recipe basically made from eggs, cream cheese, and salt. It’s called cloud bread, and it serves as a good replacement for grain-based breads, being high in protein and healthy fats

Affiliate Disclosure: this post may contain affiliate links, meaning that if you click through and buy something, I may get a small commission. This doesn’t cost you any extra and helps me build my passion for keto cooking into a livelihood. All opinions and recommendations reflect my own genuine views or those of the linked product reviewers.

Disclaimer: This article is published in good faith and for general informational purposes only. It is not a substitute for medical or nutritional advice and does not take into consideration your individual health needs. Ketolicious Kreations does not make any warranties about the ongoing completeness and reliability of this information. Always check the product label regarding allergens and other health needs. Any action you take upon the information you find on this website is strictly at your own risk. For any medical advice regarding diet and nutrition, or before changing your diet drastically, always consult a doctor or nutritionist.


Recent Posts

See All


bottom of page