In another article, I wrote about how exercise affects your blood sugar. Today will be the second part to that, where I talk about how food affects blood sugar.

So if you’re a diabetic, pre-diabetic, or know a diabetic, this may be useful to you. Actually, no. This WILL be useful to you 🙂

Here’s what we’ll cover:

  • The promised – how food affects your blood sugar
  • Three factors that influence how high and how fast blood sugar rises after a meal
  • Some FAQs: how long after eating does blood sugar return to normal?
  • What’s a normal blood sugar 1 hour after eating?
  • What should be your blood sugar immediately after eating
  • Foods that raise blood sugar
  • How food affects blood sugar

How Food Affects Blood Sugar 101 

There are basically 3 macronutrients: carbohydrates, proteins, and fats. They are called “macronutrients”, because we need them in “macro” quantities (grams per day). Then there are micronutrients. They are called “micro”, because we need them in small quantities (milligrams or micrograms). These are things like vitamins and minerals.

Since the macronutrients are the ones that have the really big effects on blood sugar, that’s what we’ll focus on.

Different macronutrients raise blood sugar to different levels.

For the most part, high-fat foods don’t raise blood sugar at all. What are high-fat foods? These are things like olives, olive oil, nuts, seeds, butter, cheese, and others. This doesn’t make them good or bad, it’s just a characteristic of these foods.

High-protein foods raise blood sugar a little bit. These foods include things like meat, fish and seafood. If you’re going to start going down the “what about” route (“what about beans?”, “what about eggs?”, “what about dairy?”), read my article on the best sources of protein here.

However, in some people, high-protein foods can actually raise blood sugar a lot. Almost as much as sugar itself. If you’re one of those people, you have to be careful. To find out if you’re one of those people, measure your blood sugar after high-protein meals.

Lastly, there are carbohydrates. Within the entire group called “carbohydrates”, there are 3 different types:

  • Fibrous carbohydrates. These are things like vegetables (with the exception of vegetables like potatoes, beets, squash, pumpkins, etc.).
  • Starchy carbohydrates. These include things like pasta, potatoes, rice, bread, etc.
  • Simple carbohydrates. These include fruit, candy, etc.

Of these, fibrous carbohydrates increase blood sugar very little. It’s the simple and starchy carbohydrates that raise blood sugar very quickly. Again, this isn’t good or bad. It’s just a characteristic of these foods.

Beyond the Basics 

So now you know the basics of nutrition, and how different macronutrients affect blood sugar levels. Now, let’s get into the deep details.

Fibre Content

The fibre content of a meal will have a very significant impact on how any given meal will affect your blood sugar levels. The higher the carbohydrates in the meal, the more the blood sugar will rise. BUT, if the fibre content of the meal is also high, it will attenuate the rise in blood sugar caused by the carbohydrates.

There is in fact a concept called “net carbohydrates.” That means that you subtract the fibre from the carbohydrate content to figure out what the net effect is on your blood sugar levels. So for example, if you eat a meal that contains 30 grams of carbohydrates, and 6 grams of fibre, the net effect on your blood sugar levels would be as if you ate 24 grams of carbohydrates. Cool, eh?

That’s why with our diabetic, pre-diabetic and insulin resistant clients, we recommend adding 2 teaspoons per meal of flax seeds, chia seeds, hemp seeds, etc.

That’s one strategy we use to help our diabetic and overweight clients get amazing results. Although it’s not directly what we’re working towards, frequently, their doctors are able to reduce their dosage of medications, or take them off the medications entirely. If you’d like help with that, you can see if you qualify for our help here. 

One way to further enhance the fibre content of your meals and support blood sugar regulation is by incorporating supplements like Colonbroom. Adding Colonbroom, which is rich in natural fibre psyllium husk, can contribute to the overall fibre content of your meals. This can help attenuate the rise in blood sugar caused by carbohydrates and promote better blood sugar control, which may lead to improved outcomes for individuals managing diabetes or weight-related issues.

Composition of the Meal

Very rarely do people eat a meal that is one macronutrient by itself. So what you eat along with your meals will affect your blood sugar levels. For example, if you eat protein and fat along with your starches, it will slow down the rise in blood sugar levels. So if your meal consists of a salad (that has olive oil as dressing), chicken, and rice, it will not raise your blood sugar nearly as much as if it was just rice and chicken.

Glycemic Index and Glycemic Load 

Different carbohydrates raise blood sugar at different speeds. The speed at which a food raises your blood sugar is called the “glycemic index.” Pure glucose will raise your blood sugar pretty quickly. But don’t confuse “pure glucose” with table sugar. Table sugar is actually a combination of glucose and fructose, so it raises blood sugar slower than pure glucose. Whereas peanuts will raise your blood sugar very slowly.

But there is just one problem with the glycemic index: it’s standardized to 50 grams of carbohydrates. It means that you’d need to eat 50 grams of carbohydrates from a certain food for the glycemic index to mean anything. So for example, you would need to eat about 250 grams of a potato to get 50 grams of carbohydrates (because a potato is made of more than just carbohydrates). But you would need to eat about 530 grams of raw carrots to get 50 grams of carbohydrates.

So low carbohydrate punks used to say “don’t eat carrots, they’re high on the glycemic index.” Sure, they’re high on the glycemic index. That’s true. But they don’t raise blood sugar that much because I don’t know of anyone who eats half a kilo of raw carrots in one sitting.

Enter the glycemic load. The glycemic load takes into account both the glycemic index, as well as the actual quantity of the food that you are eating. To figure out the glycemic load of a meal, use this formula:

Glycemic load = glycemic index /100 x net carbohydrates.

I’ll bet you didn’t think you’d have to do math in an exercise/nutrition newsletter, did you?

So while the glycemic index doesn’t matter too much, the glycemic load does. The lower the glycemic load, the lower the impact on your blood sugar. So pull out your calculator, and start crunching numbers.

FAQ #1: How Long After Eating Does Blood Sugar Return to Normal?

Before we go into the next few FAQs, take a look at this chart from Diabetes Daily of how blood sugar should behave after a meal:

How Long After Eating Does Blood Sugar Return to Normal

Now that you’ve taken a look at this chart, let’s go back to our question: “how long after eating does blood sugar return to normal?”

Another question answered with “it depends.” But fortunately, there aren’t a lot of factors here. Just whether you’re a diabetic, or not. For healthy people, who aren’t diabetics, blood sugar should return to normal within 2 hours regardless of the size and composition of that meal. However, for a diabetic, it may take longer. Much longer.

Speaking of which, what’s “normal” blood sugar? Although it varies lab to lab, most labs overlap, and agree that it’s somewhere between 4.0-5.5 mmol/l (that’s 72 mg/dl-99 mg/dl, for my American readers).

FAQ #2: What’s A Normal Blood Sugar 1 Hour After Eating?

We know that within 2 hours, blood sugar should be back to the level it was before a meal. But what about 1 hour after eating (this is called your “postprandian sugar” or “postprandial glucose”)? Generally speaking, between half an hour and 1 hour after eating is when sugar peaks.

According to at least one study, at no point in the day should blood sugar be above 7.2 mmol/l (around 130 mg/dl) in a healthy person.

And if 1 hour after eating is the peak, then I’d say it should be no higher than that. Of course, for diabetics and pre-diabetics, it will be higher.

FAQ #3: What Should Be Your Blood Sugar Immediately After Eating

Having read the first 2 FAQs, the answer to this one becomes much clearer, doesn’t it?

If fasting blood sugar is in the 4.0-5.5 mmol/l (72-99 mg/dl) range, and peak blood sugar is 7.2 mmol/l (130 mg/dl), immediately after eating, it would be somewhere in the middle, and steadily rising towards the 1-hour mark, approximately when it peaks.

FAQ #4: What Are Some Foods that Raise Blood Sugar?

The answer to this is “almost all of them.” The real question is “to what extent?”

Here are some foods that raise blood sugar  both quickly AND to a large extent (in no particular order):

  • White bread (including bagels, pita, baguette, etc.)
  • Pasta
  • White rice
  • Sweetened fruit juices
  • Pop/soda (but not diet pop/soda)
  • Most breakfast cereals that are low in fibre (you want to see 2 grams of fibre for every 10 grams of carbs)
  • Most dried fruits
  • Most pastries (muffins, donuts, cake, etc.)
  • Pancakes
  • Waffles

Basically, everything that tastes good is bad for you 🙂

Here is a list of foods that raise blood sugar just a little bit:

  • All meat, fish and seafood. Enjoy.
  • Almost all vegetables (notable exception being potatoes)
  • Almost all fruits (including bananas – they raise blood sugar quickly, but not to a very high amount)
  • All nuts and seeds (cashews, almonds, pecans, pistachios, etc.)

These lists are certainly not comprehensive. But if you do want a comprehensive list, just go here.

So there you have it. Between my last article, on the effects of exercise on blood sugar, and this article, on how food affects blood sugar, you have a pretty decent picture of the different effects on your blood sugar. You’re welcome.

If you’re interested in personal training for diabetics, check out the article in the link.