By Dr Joe
Does fruit spike insulin? Does fruit spike blood sugar?
Both questions are valid and deserve attention. Because fruits innocence can easily be mistaken. As usual I go deep on this topic.
We are encouraged to eat fruits as part of a healthy diet. Can something be this good and be just as bad for us?
Let me clarify something upfront. This piece is not saying you shouldn’t eat fruits. Rather it’s a deep insight into whether fuits can spike insulin or spike your blood sugar.
The US food and drug administration recommends 2 servings of fruits a day even amongst those whose level of physical activity is less than 30 minutes a day.
Although the official website does talk about how much fruit you need daily would depend on age, sex and physical activity.
In the UK, we are advised to eat 5 portions of fruits and veg daily to keep the doctors away from our doorstep.
All in all, you are encouraged to consume fruits daily. Any fruit. In any form.
I will disagree with some aspects of the recommendation especially if we are going to answer the question of whether fruits can spike blood sugar or spike insulin.
You will see what I mean as I delve deeper into the fruits and blood sugar & insulin connection.
Not that we need any encouragement to eat fruits anyway. The mere fact of their sweetness and fleshy texture is enough to make us fall in love with fruits.
Our love for fruits is evolutionary. In the prehistoric times over 2 million years ago, our diet was carbohydrate-poor, rich in protein and fat.
At the time, the only way we satisfied our sweet tooth was through fruit consumption. Fruits were more pleasant on the palate than leaves and roots. Indeed, it was important to have these substitutes when the hunter-gatherer couldn’t make a catch.
Instead of going hungry because the deer survived our hunting attempt, you had berries, veggies and roots to fall back on. Not a big deal.
Whilst it made sense at the time to eat all fruits that came our way, so long as they were considered safe, our modern way of life has now thrown some questions regarding the effects of fruits on blood sugar and insulin.
This is inextricably tied up to our modern lifestyle of being sedentary. All of these do have implications as to how our body deals with the sugar that erupts from the fruits we eat.
So, does fruit spike blood sugar and insulin?
Well, the answer is, Yes and No.
Yes, fruits can spike blood sugar.
Yes, fruits can spike insulin.
And No, fruits may neither spike blood sugar nor insulin.
Confused? Don’t be.
And I’m not giving a cop-out answer here. You know I am not one for sitting on the fence. It hurts the bum…badly.
Whether fruits spike blood insulin or spike blood sugar or not, depends on a number of factors.
And this would vary from person to person. In fact, whether your blood sugar or your insulin spikes after you eat fruit can also vary within you as an individual.
Here are some of the factors that would determine if fruits will spike your insulin or spike your blood sugar:
- Type of fruit
- How the fruit is eaten
- How much of the fruit you eat
- What you eat the fruit with
- Where you are in your metabolic health
- Your level of physical activity
Let’s take each of those factors and see how they play out.
1. Type of fruit
I don’t need to tell you that some fruits are sweeter than others. Even the same fruit can have different variations. Think Green Apples and Red Apples.
Red apples are tastier than green apples. Green apples sometimes border on the savoury side than sweet. Amongst the red apples, I’ve lost count of how many types my supermarket throws at me. Choices, choices, choices.
I’m encouraged to buy some brands of red apples because according to my supermarket, they are sweeter.
That’s just apples.
If you take things further and compare sugar between fruits, that could take a huge table of facts that might be difficult to digest (no pun intended).
So, I will keep things simple.
The amount of sugar in cantaloupe or honeydew melon is twice the amount in strawberries. Gram for gram you will be getting double the dose of sugar from honeydew melon and cantaloupe than you would, if you ate strawberries.
What about pineapples and mangoes? They are in a different league.
The flipside of that is there are some fruits that you will consider as being very safe as far as blood sugar spiking and insulin spiking are concerned.
Raspberries, blueberries, blackberries, strawberries are generally safe fruits for blood sugar and insulin spikes. So safe the berries are that diabetics are actually encouraged to eat them.
If you take things a little further in terms of fruits safety from blood sugar spikes, avocado is one fruit that should be considered a safe bet. Avocados are fatty though but the sugar level is pretty tolerable. Just something to bear in mind.
Depending on the other factors that I will be discussing shortly, a certain fruit can spike your insulin correspondingly after spiking your blood sugar on a given day.
What fruit you eat matters.
2. How the fruit is eaten
If you eat fruits whole and fresh, the soluble and insoluble fibre in the fruit keeps the release of sugars from the fruit in check.
There is a reason people like Eric Rimm from Harvard School of Public Health recommend that fruits be eaten whole.
Fruits contain not just natural sugars but also fibre and micronutrients. The fibre in fruits is both soluble and insoluble. The soluble fibre is what stops the fruit from releasing the natural sugars briskly.
The insoluble fiber does other things like serving as a prebiotic to our gut bacteria. Not only that, insoluble fiber helps move food along the alimentary tract, keeping us regular (if you get my drift).
I like making smoothies and of course I make my own smoothies. You should too.
However, I have had to rein in my love of smoothies because the process of making smoothies does break down the fibre we are talking about.
When you blitz the fruits in your smoothie machine, you are blitzing the fibre and altering the digestibility of the fruits.
In theory, you are encouraging the sugars in the fruits to be released a little quicker than they would, if you ate and chewed your fruits whole.
The finer the texture of your smoothie, the higher this effect.
Now, I should add that this effect may not be too significant in a person who is metabolically competent. I will touch on this shortly.
From the above, you would have gathered that if you are going to consume smoothies, please make your own smoothies. At least you know what’s gone into the smoothie.
Never buy smoothies from the shops or your supermarket. They invariably add sugars to those commercially available smoothies. You will be shocked at how much sugar is added.
As if the fruit isn’t sweet enough?
The point here being, whereas eating a whole fruit may not spike your blood sugar or spike your insulin, the smoothie version may spike your blood sugar and insulin.
The only way to find out is; if you test yourself using a blood glucose meter eating both versions. I encourage you to test yourself, by the way. More so, if you have insulin resistance, prediabetes or diabetes.
Lest I forget. Dried fruits and Canned fruits.
Whereas fresh fruits might be good for your blood sugar and insulin, the dried version of the fruit may turn out to be a devil in disguise.
Think grapes and raisins. Do you think eating 30 grapes will have the same effect as eating 30 raisins?
For a start, 30 grapes will fill you up more, 30 raisins will do no such thing. Agreed?
Secondly, the release of simple natural sugars from the raisins will be faster than you get from the grapes even though both the grapes and the raisins have the same amount of sugar.
It is the speed of sugar release that will affect the likelihood of a blood sugar spike and a corresponding insulin spike.
Dried fruits will certainly move you in that direction.
Dried fruits are fruits that have lost nearly all the water content. Not only that some food manufacturers are crazy enough to add sugar to some dried fruits to sweeten them up some more.
How much sweetness do we need in our lives?
Think dried berries, cherries and apricots.
The same goes for canned fruits. Some have added sugar in them. Avoid.
If you ever going to have canned fruits, ensure they are preserved in water. If there’s any added sugar, avoid.
Because those brands of canned fruits with added sugar will most certainly spike your blood sugar and spike your insulin.
3. How much of the fruit you eat
This is common sense really.
If you are going to gorge on something sweet, it makes sense to be sensible about it.
If you are going to eat 10 apples in one sitting because you are chatting with your friend and you’ve lost track of how much apples you have eaten (10 actually, need I remind you), is it any surprise if the apples spike your blood sugar and your insulin?
Then again, it also depends on other factors playing up to either protect you or conspire against you. I’m referring to the type of fruit, how you eat it, your metabolic status etc.
All of those factors will determine whether 10 apples or 10 oranges may spike you or not.
I’m not one to talk, because I actually eat lots of bananas. The most bananas I have eaten is 5 in one sitting. But I was fine. I’m no longer insulin resistant and the bananas by the way are the minimally-ripe ones not the deep yellow over ripe ones with brown patches on the skin.
I eat lots of minimally-ripe bananas to catch up on my resistant starch.
I’m pretty sure if I ate 5 of those over-ripe bananas, my blood sugar will rocket up.
And I don’t eat those bananas blindly, by the way. I have a glucometer and I check my blood sugar to ensure I am not being reckless.
Okay, I could get away with eating lots of bananas, will I get away with eating lots of honeydew melon?
I’m not so sure. I haven’t tested it, so I can’t say.
What I can tell you though is; honeydew melon is a fruit that is not only high in sugar (we established that already earlier on) but low in fibre.
And as you know, melons are so soft that the texture is almost non-existent.
What does that mean?
It means you can easily eat lots and lots of a fruit like watermelon without realising you have. In addition, the fact that watermelon or honeydew melon has very little fiber means fruits like honeydew melon or watermelon will give you a blood sugar spike and an insulin spike.
The way round it is, if you are going to eat fruits like melon with high sugar and low fiber, you will need to reduce your portion sizes to less than a cup.
High fiber fruits like the berries are a safer bet when it comes to eating bigger portions of fruits, if you want to avoid insulin spike and blood sugar spike.
Something else I need to mention about canned fruits is that you can very easily eats lots of canned fruits than you would eating the whole fruit version of it.
You need to be mindful of that.
4. What you eat the fruits with
Before I started writing this article, I had some fruit. Apples and Blueberries.
But I didn’t just eat the apples and blueberries on their own, I had the them with oatmeal.
I like doing that. Why?
Because oatmeal as you know has lots and lots of fibre. Fiber is good for you.
Oat meal has fibre. The apple has fiber. The blueberries have fiber. What have I succeeded in doing with that combination?
Not only have I succeeded in boosting my fiber intake for the day, I have also ensured that the release of blood sugar from that meal is as slow as it will ever get.
You can apply the same principle of introducing more fiber to your fruit intake by having your fruits with leafy green vegetables, if oatmeal is not your thing.
Leafy greens have lots of fibre to boot. You can’t go wrong with them. In fact, I will go as far as saying fruits like honeydew melon with low fiber content on their own, are best eaten as eaten as salads with leafy green vegetables.
The flipside of that is what my teenage son did the other day.
I came downstairs to the kitchen and saw him having strawberries. How cool is that? A teenager having fruit?
They usually have little interest in fruits. But wait for it…
He was having the strawberries with sugar draped over them. Yes, he was. See image below.
Strawberries are supposed to be one of the best fruits you can ever eat. But here we have a situation where my son was turning one of the healthiest fruits into something potentially unhealthy.
Will a combination like this cause the fruit to spike your blood sugar and spike your insulin? Very likely.
5. Where you are in your metabolic health
I have sort of touched on this in a roundabout way already.
We are all at different places in our metabolic health. Some of us are still metabolically competent. However, 24% of adult population in the US for instance, is thought to be insulin resistant.
Others are quite frankly diabetic.
How the fruit you eat interacts with you is strongly dependent on your metabolic status. The older you are, the higher the likelihood that you may be metabolically incompetent.
Which means fruits that wouldn’t spike you in your 20s will now spike your blood sugar in your 40s and beyond. Because you are probably insulin resistant.
Fruits like bananas, watermelon, apples, pears, nectarines, apricots, oranges, pineapples etc are fruits that won’t do someone with insulin resistance, prediabetes and diabetes any favours especially when eaten on their own.
But if you can make yourself insulin sensitive, then you may well welcome these fruits back into your life without any hassles.
How do you eat fruits without spiking your blood sugar if you are insulin resistant, have prediabetes or have type 2 diabetes?
Look out for these tips later on.
6. Your level of physical activity
Nothing beats the cellular capabilities of someone who is physically active. You hear it everywhere. Exercise, exercise, exercise.
Most advice on exercise is geared towards weight loss. That is correct but I do think that’s a misplaced advice. Exercise does little for weight loss and I mean that.
Exercise does a whole lot more for improving your metabolic health than it will ever do to make you shed fat.
If you do nothing else, do your exercises to boost your metabolic health.
The principal gain from exercise is improving insulin sensitivity.
If you built muscle as a result of your exercise activity, even better.
Muscle soaks up glucose from the blood circulation thereby lowering blood sugar. This prevents blood sugar spike and insulin spike.
Even if you don’t build muscle, just doing regular exercise will sensitize your muscles and make them more responsive to insulin.
If you boost your insulin sensitivity, fruits you eat will not cause a blood sugar spike and will therefore not cause insulin spike.
If you do nothing else, just increase your level of physical activity. You don’t have to visit the gym. See how you can boost your metabolic advantage by doing the things you do every day better.
As you can tell, the implication is; if you are very sedentary, you increase your risk of having fruits spiking your blood sugar and spiking your insulin.
Being sedentary is one of the worst things you can ever do to your metabolic and overall health.
Okay, here is how you can eat fruits without spiking your blood sugar or spiking your insulin:
- Eat high fiber fruits
- If eating low fiber fruits, keep quantity small
- Avoid dried fruits
- Eat whole fresh fruits
- Avoid fruit juice
- Avoid shop-bought smoothies
- Make your own smoothies instead. Whole fruits better than smoothies though.
- Avoid canned fruits
- Add more fiber to your fruits by eating fruits with other high fiber foods in combination
- Eating fruits with protein like nuts, nut butter or seeds can also slow down digestion
- Don’t eat fruits with added sugar
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