Do snacks cause blood sugar spikes? How to handle them correctly

Do snacks cause blood sugar spikes?

When you get hungry in the afternoon and reach for something sweet or a piece of bread, do you ever worry about a blood sugar spike? This article explains the meaning of the term "blood sugar spike" and why you can't simply say that snacking is bad for your health.

What does "blood sugar spike" actually mean?

Do you think a blood sugar spike is an official medical diagnosis that appears on health checkup results? According to materials from the Saiseikai Imperial Gift Foundation, a blood sugar spike is not an official diagnostic name but a general term referring to a state where blood sugar levels rise and fall rapidly after a meal (Saiseikai "Let's prevent blood sugar spikes"). Even if you feel sleepy or lethargic after a snack, you cannot definitively state that a blood sugar spike has occurred. For example, if you feel sleepy after eating a sweet bun in the afternoon, it is important not to attribute the cause solely to a "blood sugar spike."

Why snacking itself isn't necessarily bad

Once you realize that a blood sugar spike is a general expression rather than a medical diagnosis, you will see that you don't need to be on guard as if every snack is harmful. How blood sugar rises depends on what you eat, how much, and at what intervals. When choosing a snack, it is important not only to look at the amount of sugar, but also to consider the combination with protein and dietary fiber, as well as the time until your next meal. We recommend keeping the portion size modest and enjoying your snack in a way that does not affect your next meal.

Characteristics of snacks that cause blood sugar to rise

Snacks high in carbohydrates, such as canned coffee and sweet buns, are combinations that easily raise blood sugar levels. Here, we explain which eating habits and choices tend to cause significant fluctuations in blood sugar, along with specific examples.

Why sweet drinks and sweet buns easily raise blood sugar

Many people likely snack by having a canned coffee and a sweet bun together during work. Soft drinks and sweet buns are foods high in carbohydrates derived from sugar and flour. If you eat a canned coffee and a sweet bun consecutively, the total sugar content per snack tends to be higher than usual because both contain carbohydrates. By comparing the carbohydrate or sugar labels when selecting items, you can confirm in advance whether the combination is too high in sugar. Simply replacing either the drink or the food with a low-carb alternative can change the overall sugar content of the snack. If you want to reconsider your usual snacking habits, "Can you buy low-carb snacks in stores? How to choose and recommendations" may also be helpful.

Characteristics of people prone to blood sugar spikes

Because "blood sugar spike" is a general term and not an official diagnosis, it is impossible to define a single set of characteristics for those prone to it. Here, let's consider it from the perspective of how you choose your usual snacks. For example, people who repeatedly nibble on chocolate or candy during meetings increase both the frequency and the amount of sugar they consume throughout the day. In particular, people who have a habit of choosing sweet snacks at the same time every day may find it difficult to be conscious of their total sugar intake. Even if you consume the same amount of sugar, the total sugar content of your snacks for the day will change depending on whether you eat it all at once or spread it out. A good place to start is to reflect on whether your usual snacks are biased toward sweets and whether the amount is consistent.

How to decide the interval, amount, and timing of snacks?

For snacks, not only "what you eat," but also "when and how much" affects how your blood sugar rises. Let's think about the timing of snacks using two yardsticks: the duration of hunger and the quantity.

The relationship between hunger time and blood sugar after snacking

Many people likely have lunch at 12:00 and feel a bit hungry around 15:00. A Scientific Research Grant-in-Aid research report compared individuals consuming a 500 kcal Baumkuchen immediately after lunch, between lunch and dinner, and immediately after dinner. It reported that when eaten around 15:00 to 16:00, blood sugar levels rose less easily than when eaten immediately after lunch or dinner, and the overall daily fluctuation range of blood sugar was also smaller. If you are going to have a snack in the afternoon, it is best to choose a time when some time has passed since lunch and there is still some time until dinner.

Guidelines for snack portion sizes

There is no uniform standard for how many grams a snack should be. The appropriate amount for a "single serving" changes depending on whether you had a substantial lunch or had little appetite and ate very little from the morning. Clues for deciding the amount include what you have already eaten that day and the calories and sugar values listed on the product. If you settle for a small snack on a day you are very hungry, you might end up overeating later. Conversely, if you add the same amount of snacks on a day when you have already eaten a lot, it is easy to exceed your daily intake. We recommend adjusting the amount of your snack each time by checking it against how much you have already eaten that day.

The relationship between two meals a day and snacking

People who eat two meals a day tend to have longer gaps between meals compared to those who eat three, and the timing of their snacks will also differ. As mentioned in the research above, it was reported that blood sugar was less likely to rise when the snack was eaten after some time had passed since lunch and while there was still time until the next meal. People who are prone to long gaps between meals should be more conscious about the timing of their snacks.

Does one rice ball cause a blood sugar spike?

When you are a little hungry, you might choose a single rice ball, which can be eaten with one hand, as a snack. Rice balls are primarily made of rice, which is high in carbohydrates. Therefore, you cannot say that one rice ball won't raise your blood sugar just because it is small. In fact, a single rice ball can be closer to a light meal than a snack. If you eat one rice ball at once after a long period of hunger, your blood sugar might fluctuate significantly. Days when you find yourself reaching for a second one are a good opportunity to reconsider if one is enough. Choosing a smaller size, or eating half and saving the rest for your next snack, makes it easier to adjust the portion. When choosing rice balls at a convenience store, be sure to check the carbohydrate content on the package.

What should you look at on the nutritional information label when choosing snacks?

When choosing a snack, do you ever get confused by the various numbers on the package and wonder where to look? Knowing the meaning of each item on the nutritional information label will provide you with criteria for comparing products.

Differences between carbohydrates, sugars, and saccharides

When you pick up a rice ball or snack at a convenience store, have you ever returned it to the shelf without knowing which one to look at because similar terms like "carbohydrates," "sugars," and "saccharides" are listed? The Consumer Affairs Agency states that nutritional information must be listed in the order of calories, protein, fat, carbohydrates, and sodium (salt equivalent) (Consumer Affairs Agency "On Nutritional Information Labeling"). The same document also notes that while carbohydrates are a mandatory item, whether to display sugars or saccharides is up to each individual manufacturer. When choosing a snack, first check the sugar content of the product you have picked up.

How to combine with protein and dietary fiber

The nutritional information label lists not only carbohydrates and sugars but also the amounts of protein and dietary fiber. When choosing yogurt or nuts as a snack, comparing these two values is one effective method. Even for products with around 100 kcal, the amounts of protein and dietary fiber differ by product. You don't need to memorize the values every time. Simply picking up two products in front of the shelf and comparing the labels will provide you with the information you need to choose your snack for the day. Since dietary fiber is sometimes listed as a sub-item of carbohydrates, we recommend looking at the breakdown section rather than stopping at the carbohydrate value.

Related content is introduced in "How long does sleepiness from a blood sugar spike last? Causes and countermeasures" and "How to choose and eat snacks that don't easily raise blood sugar," so please refer to those as well.

Comparing nutritional information using BRAIN PRO as an example

When you're not sure what to choose for a snack, let's look at an example using BRAIN PRO to see where you should compare nutritional information. We will check the specific values of sugars and protein, as well as the ingredients.

Viewing the balance of sugars and protein in a comparison table

When you pick up a protein bar because you are hungry in the afternoon, you might be confused about which numbers on the package to look at. BRAIN PRO displays the following per 35g bar:

Product	Content	Sugars	Artificial Sweeteners	White Sugar	Protein (Source)
Cream Genmai Bran Cacao	36g	17g	None	Used	5g / Soy
1-pon Manzoku Bar Protein White	39g	9.8g	None	Used	16g / Soy/Milk
Zavas Protein Bar 1/2 Day's Iron Royal Milk Tea Flavor	38g	Not listed (Saccharides 6.4g)	Used (Sucralose)	Used	14.7g / Milk/Soy
in Bar Protein Baked Bitter	42g	2.3–5.0g	Used (Sucralose)	Used	15.9g / Milk/Soy
BRAIN PRO	35g	4.9g	None	None	11.1g / Plant-based (Pea)

The values for each product are based on nutritional information posted on the manufacturers' official websites as of September 25, 2026. Values may change due to product revisions.

Of the 7.1g of carbohydrates, 4.9g are sugars. When compared with 11.1g of protein, the proportion of protein is higher than that of sugars. Since it is not uncommon for the sugar content of sweet buns and snack foods to significantly exceed the protein content, this difference in ratio is an easy-to-understand decision-making factor for those who have a habit of comparing nutritional information. We recommend BRAIN PRO for those who want to choose snacks while checking the amount of sugar.

BRAIN PRO ingredients and nutritional information

The ingredients in BRAIN PRO are almond paste, pea protein, almonds, soy puffs, cocoa powder, coconut oil, cacao butter, inulin syrup, agave syrup, yamabushitake (lion's mane) powder, rock salt, flavoring, and sweetener (stevia). No white sugar is used, and sweetness is provided by stevia and agave syrup. Preservatives, colorings, trans fats, and animal-derived ingredients are also not used.

However, since it contains soy and almonds as ingredients, those with allergies to these should be careful. BRAIN PRO is suitable for those who want to check the ingredients before choosing a snack or those who want to avoid white sugar.

How to check for changes in your body after snacking

If you feel sleepy or lethargic after snacking, you might be worried that it's a blood sugar spike. Let's look at what criteria to use rather than relying solely on your physical sensations.

Sleepiness and lethargy are not determined solely by blood sugar

When you feel very sleepy during an afternoon meeting, do you automatically blame your snack? Sleepiness and lethargy are caused by factors other than blood sugar, such as sleep deprivation, temperature, and the nature of your work. As mentioned above, a blood sugar spike is not an official medical diagnosis, so you cannot determine that a "blood sugar spike is occurring" based solely on physical sensations. Afternoon sleepiness itself is discussed in detail in "Is afternoon sleepiness caused by blood sugar? How to distinguish it and how to reconsider your lunch." If symptoms persist even after changing the content or amount of your snacks, it is a good idea to reflect on other potential causes as well.

When to consult a doctor if symptoms persist

If you feel that strong sleepiness or lethargy persists every time you have a snack, we recommend consulting a medical institution rather than relying on your own judgment. The clinical guidelines of the Japan Diabetes Society indicate that for a normal classification, the fasting blood glucose level should be less than 110 mg/dL and the 2-hour value of a 75g oral glucose tolerance test should be less than 140 mg/dL (Japan Diabetes Society "Diabetes Clinical Practice Guideline 2024"). Such values can only be determined through tests at a medical institution, not by self-diagnosis. If you have any concerns about persistent symptoms, consider a health checkup or a consultation at a medical institution.

Frequently Asked Questions

Is there a way to completely eliminate blood sugar spikes?

There is no way to definitively state that you can completely eliminate blood sugar spikes through snacking adjustments. A blood sugar spike is not a diagnosis but a term referring to a state where blood sugar levels rise and fall rapidly after a meal, and the rise depends on the amount, interval, and combination of snacks. Continuing to make adjustments, such as choosing snacks while checking sugar content and keeping portions moderate, is a realistic way to approach this.

Do blood sugar spikes occur in people who are not overweight?

The materials checked for this article do not provide evidence that allows us to say whether or not they occur based on weight or body type. If you are concerned about fluctuations in blood sugar, do not judge based on your physical sensations, and consider a health checkup or an examination at a medical institution.

Summary

Snacking itself is not necessarily the cause of blood sugar spikes; how blood sugar rises changes depending on the intervals, amounts, and combinations of foods eaten. Having a habit of checking the amounts of sugar, protein, and dietary fiber on nutritional labels will make it easier to choose your daily snacks. It is recommended that you do not judge based on your physical sensations alone, and consult a medical institution if you have any concerns about persistent symptoms.