Do Bananas Make You Fat? The Truth About Fructose



Today, we talk about the truth about fructose and what it does to your body. Can you handle the truth?

When you think of the word “fructose,” what comes to mind? Maybe you’re a little confused about good sugar vs. bad sugar. There has been talk back and forth about whether fruit is truly healthy, and in what quantities?

Some even argue that, because fruit has fructose in it, it can have some unfortunate effects on your body. But how can fruit possibly be bad for you, when we spend our whole lives thinking it’s good for us?

All this talk has some worried that fruit is going to make them fat. These folks might also be surprised to find out that others can eat up to 100 grams of carbs in a day. So can fruit really make you fat? There’s just so much misinformation about sugar and half truth flying around that we wanted to clear the air.

Today we’ll clear the air and set the record straight on fructose.

Amongst the latest and greatest in the diet and nutrition world, there have been some pretty harsh claims thrown towards fructose.

The Truth About Fructose: What Does Science Say?

Does the name Dr. Robert H. Lustig ring any bells? It might. He’s a pretty big name among those who hate fruit. He has a talk called Sugar: The Bitter Truth. With over 3 million views on YouTube, Dr. Lustig believe that fructose has a few special qualities that are directly connected with fat storage. Therefore, this makes fructose pretty toxic to the liver. 

But are these based on opinions or facts? What type of evidence is there to support these findings? Does this mean fructose, and essentially fruit, aren’t good for us? Do bananas make us fat? What about strawberries and cherries and mangoes and oranges? 

Let’s first breakdown what fructose is and why it matters. Fructose is a type of simple carb that makes up sucrose (which is basically table sugar) once it’s combined with glucose. You can find it in a tone of plant sources, including things like fruits, flowers, root veggies and honey. Fructose is one of 3 forms of sugar that each one of our body’s need in the form of fuel. These other two forms of sugar are galactose and glucose.

When you eat a lot of refined sugars (yes, we’re including fructose here), you’re going to see some problems outside of just the additional calories you’re getting.

We know this is generally associated with drug abuse, but it can be the same for sugars, too. Plus, it has some crazy symptoms, including withdrawal symptoms ranging from cravings to binging. When you have sugar on a regular basis, sweetened beverages, this can contribute to weight gain and obesity. Plus, high amounts of sugar has been linked to an increase risk of cancer in both women and men.

This stuff is no joke. If you’re not taking it seriously by now, it’s time to recalculate.

And if we’re going to listen to these fructose haters, this molecule specifically is the one to be avoided. For example, there’s been some major research that shows consuming fructose on a regular basis plays a big role in the development of many diseases. These can be everything from heart disease, hyptertension, to obesity, metabolic syndrome, diabetes, and kidney disease.

These types of studies then cause people to give advice about avoiding both fruit and fructose. And the people listening hear Don’t eat a ton of fruit. The less fruit you consume, the better you’ll be. But frankly, the truth about sugar isn’t this simple, not when it comes to fructose. There’s a lot more that goes along with this and fruit is not your enemy. 


Consuming Fructose Vs Eating Fruit: Understanding a Key Difference You Might Be Missing

When you really start looking into the clinical trials that focus on the health problems generally connected to the volunteer’s fructose intake, there’s a pretty big red flag that some people miss. Here’s the deal:

The fructose was given in incredibly high dosages, which in turn caused negative effects. While you might be able to reach these insanely high dosages if you’re drinking 2 cases of soda a day and eating candy, you certainly aren’t going to get anywhere near them with just fruit. 

So is too much fructose bad for you? Definitely. Are you going to reach that level eating fruit? Hardly likely.

A study conducted by the University of Lausanne focused on a diet high in fructose for seven days. Needless to say, it showed that fat deposits in both the muscle and the liver increased. Plus, there was a big decrease in insulin sensitivity. Not good at all.

But what were the details surrounding this study? A total of 16 guys would drink a solution that contained around 3.5 grams of fructose for every kg of weight on a daily basis. Let’s say you weight 90 kilograms. That means you would be consuming around 315 grams of fructose on a daily basis.

That sounds like a lot, so you should definitely avoid fruit, right? Wrong…

Allow us to put this in perspective. In order to get 315 grams of fructose from say, a banana, you’d have to eat 45 of them. That’s a lot of bananas. How about strawberries? Well, to get 315 grams of fructose from them, you’re looking at eating about 80 cups of strawberries. We love strawberries but we don’t know if we love them that much. Apples, you’d have to eat 26 of them. How about cherries? You’re looking at about 800 cherries. We don’t think that’s doable in one sitting, but that’s just us. The biggest humans in the gym don’t have that much fruit in their post workout meals.

Let’s take a look at another study to see what they had to say about it.

University of California Fructose Study

For this one, the University of California stepped up to the plate. They had a group of volunteers get 25% of their calories on a daily basis from two things: either from fructose or glucose.

Once 12 weeks passed, the researchers found some pretty drastic results. Both groups (those who ate fructose and those who are glucose) had obviously gained a lot of weight, because they were overeating.

However, here’s the interesting piece of this puzzle. The group that was getting 25% of their daily calories from fructose didn’t see the harmful side effects that the group eating the glucose saw.

Some of these side effects were a lot worse than others. The glucose group say things like an huge jump in visceral fat, as well as a jump in fat production within their livers. They also saw there was a decrease in insulin sensitivity, with a surge in LDL (you know it as the ‘bad’ cholesterol) levels. The researchers also found the glucose group had an increase in their triglyceride levels.

So yeah, the glucose group didn’t make out too great here.

But think about it – glucose or fructose made up 25% of their calories on a daily basis for 12 weeks? That’s pretty intense. If you eat 2,500 calories a day, that’s a little under 150 grams of fructose on a daily basis. We already bombarded you with the fruit list in comparison to fructose grams so we won’t do that again, but you probably have a clear idea about this – you’d have to eat a ton of fruit to get even close to that dose.

Dispelling Other Claims About Fructose

Needless to say, eating large, large amounts of fructose on a daily/regular basis is definitely not a good thing. But, in order to come anywhere close to that number in regards to consuming fruit, you’d have to be insane – and probably pretty rich to afford buying all that fruit, especially if you’re going through 800 cherries a day.

Another common claim against the hated fructose is that it can cause a lot more weight gain than various other types of carbs, no matter how much you’re ingesting. That seems a little strange doesn’t it? How can something be assumed to make you gain more weight when you can’t even have a solid measurement to compare it again?

Yet another favored claim is that fructose is toxic to the liver. In some pretty dramatic cases, fructose is compared to alcohol in terms of what it does to the liver.

But here’s the thing – these kinds of accusations aren’t supported by any type of studies that are done on humans. Again, these studies were conducted on animals like mice and rats. Obviously, there are some huge, huge differences, especially with metabolic functions, between mice/rats and humans. So how can we possibly assume that our systems respond the same way, when they function in two totally different ways?

fructose myths

A Study on Fructose and the Liver

There’s been some research that shows a measly 2-3% of fructose that you consume is actually changed into fat when it’s in the liver. What happens to the other parts of it, you ask? Well 50% of it ends up as glucose, while the other 25% changes to lactate and the remaining 15% heads off as glycogen.

So this could be why McMaster University decided to publish their meta-analysis in 2012. The university published a study that was conducted when 637 were involved in 31 fructose feeding trials. The study stated that fructose did not seem to cause any weight gain when it was subbed out for other carbs and the calorie intake remained around the same.

While you might be part of the team that’s quick to point out lactate production becoming a problem, these so-called claims were called out as false over 10 years ago. Lactate isn’t exactly a metabolic troublemaker. Rather, it plays a large role in countless metabolic processes and is actually considered a fuel for us.

Here’s what’s important to keep in mind – fructose is going to cause you to gain weight when you indulge in overeating, which is just like any other type of calorie out there.  It doesn’t have some power that makes you gain 1,000 pounds overnight and it certainly doesn’t do any harm when you consume it on a pretty moderate basis. 

Fructose and the Fiber Effect

There’s also something else to consider here too. Because fruit has such high amounts of fiber in it, it’s going to alter the way our bodies handle the sugar that comes along with fruit. So we can’t just say a piece of fruit has this much fructose and that’s it. There are other things to consider here.

First off, since we’re on the subject, ask yourself, are you getting enough fiber

We’re curious to see if any university or researcher decides to gather up a group of volunteers and start them up on an 800 cherries/29 apples/150 orange diet. Now that’s something we would be interesting in seeing.

All in all, fruit is always the better choice, no matter what you hear from these studies. Whether you are carb cycling, or just trying to maintain a healthy weight, fruit is a healthy source of energy. When you’re focused on building muscle while burning fat, fruit stokes your metabolism after a workout and aids in protein synthesis for building new muscle.

For example, let’s say you’re going to get 30 grams of fructose today and that’s all you will allow yourself. Would you prefer to get those 30 grams of fructose from a few pieces of fruit, or do you want to reach for some kind of juice that’s filled with sugar and has 30 grams of pure fructose in one cup? Some of these can come in high-fructose corn syrup shape, too. But obviously, the fruit is the better choice here.

Odds are, the juice doesn’t offer much in the way of health or even satiety. The fruit, however, is bursting full of essential vitamins and nutrients. Plus, it’s going to help keep you fuller for longer – at least more than juice will do.

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We’ll end on a good note – how much fructose should you consume on a regular basis? Well, if you take a look at some of these clinical studies that focus on fructose consumption, taking in about 25 to 40 grams on regular basis is going to be safe (from fruit). Before you start counting out the cherries, we will tell you that’s the equivalent of eating 3 to 6 bananas, up to 15 cherries, 3 apples, or 10 cups of strawberries. Even the biggest fruit lover in the world would have trouble eating that much fruit, so odds are, you are totally fine.

-Terry Asher


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Gym Junkies Founder & Editor in Chief at Gym Junkies LLC
I’m Terry and I’m here to help you achieve your fitness goals. I truly believe anyone can achieve the figure they want with the proper guidance. Through my extensive fitness blog, top fitness videos, leading workout supplements, and top selling eBooks, I have been able to help thousands of people online lose weight, tone up and get in shape. My passion is helping people all around the world change their lives for the better.
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  1. I eat more fruits then I should (after all it’s summer). I am glad that you posted this article, it will make me think before reaching for that second piece of fruit!! I know that I could eat 800 cherries in a day!! Never enough cherries? — thank you

  2. Great post! I ‘ve definitely heard people say that fruit is not a good healthy food. I now understand why they are saying this, but thank you for clearing the air. Thank you for sharing!

  3. Hi Terry,

    I think you make some excellent points in this article, but I want to ask you what your opinion on “Freelee the Banana Girl,” is. I don’t know if you have heard of her, but she has a vegan youtube channel. I like to do my own research concerning fitness and proper diets for such a lifestyle and in doing so, I ran across her channel. She has a mostly fruit based diet, so I am curious what your thoughts are on her diet and work-out regime (she does a lot of the boring, endless cardio).

    Thanks in advance,

  4. Hey Marie,

    I have not heard of her, but I will check her stuff out. I tend to be more of a fan of diets that utilize all three macronutrients though. I also tend to stick with whole food based diets. Nevertheless, I will check her stuff out!



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