The Facts of Fructose – Specific Reasons To Avoid It.

0013 Feature Skull of Sugar

[DISCLAIMER: I’m not a doctor, nor do I play one on the Internet. Speak with a medical professional before doing anything medical-related] [13]


— “Fructose, or fruit sugar, is a simple ketonic monosaccharide found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. “ [2]

Not all sugar is created equal and this is especially true for fructose. Fructose is a sugar that is digested much differently than regular sugars, and affects your health much differently as a result. Fructose is commonly misinterpreted as healthy natural sugar when it is factually more problematic than glucose or starches when we take a look at the biological facts once ingested. For more of an introductory look at just fruit and sugar in general please go here. (Fruit! Health food or just eye catching click bait?)  For a deeper dive into the impacts of just fructose, keep reading. 🙂

Fructose and Fat Loss

Fructose unlike starches and glucose can not be used as fuel until processed by the liver. All fructose consumed must be processed by the liver before it can be used as fuel. The liver conversion process is automatically lipogenic to start things off. This means it will produce a certain amount of fat and specifically the visceral (bad) fat that surrounds your organs, not the kind of fat that is under your skin. [1][5] This type of fat is linked with Heart Disease as well as Fatty Liver Disease. These are both extreme cases and diseases that take a long time to manifest, however, in the short term there are also other things to consider.

Let’s explore the relation to burning extra body fat and going back to the point about fructose skipping right to the liver. Starch and glucose can be used up and stored in the blood, muscles, and lastly surpluses stored in the liver. This is important because as discussed in a prior article, the amount of stored glucose in the liver is a signal to turn the body’s fat burning on or off. When eating fructose, you are sending a direct supply and signal to the liver to turn off fat burning in the form of glucose that skips both blood and muscle storage locations.

“Ketone bodies are formed by ketogenesis when liver glycogen stores are depleted” – [7]

Fructose and Metabolic Syndrome

Consumption of fructose increases insulin resistance, which results in poor metabolic function. [3] In very basic terms, you will not be able to eat as many carbohydrates and remain healthy. Most importantly, carbohydrates are delicious, so for sanity sake we want to be able to eat as many of them as possible while reaching our goals. 😉

Limiting carbohydrate consumption (Especially Fructose) and increasing fat consumption (omega-3’s and non-oxidized saturated fats) has been shown to reduce insulin sensitivity issues, and improve cholesterol markers. [3][4] Inversely increased intake of fructose has not only been shown to increase insulin resistance but also to create more smaller LDL particles, which is the number 1 risk factor for the number 1 killer, heart disease. [1][3][8]

Fructose, Alzheimer’s and Aging

Alzheimer’s is also known in the medical community as Type-3 Diabetes, which makes perfect sense when you know fructose accelerates insulin resistance. [3] Alzheimer’s is just a form of insulin resistance, but in the brain. [9] Some people say they don’t care how their body looks as long as their brain works fine. Alzheimer’s being caused by a compromised metabolic system means that with poor diet you will lose your mind quicker as well. Both mind and body are affected, which is why I focus primarily on metabolic health.

For aging, excessive long term fructose consumption accelerates age related markers in a rat study. [10] How this applies to humans directly needs to be studied further, but having a compromised metabolic system, will for sure age your mind and body quicker.

Positive Effects of Fructose on Health

To be honest, I have yet to find any and have searched high and low. The only argument I have come across is that it does not increase blood glucose, however in doing so puts the entire glycemic load on the liver, which brings us back to our first issue with fructose.

Fruit sugar in an orange

Fruits are one of those sneaky foods that sabotage people into falling short of their fat loss goals.

I think that excessive fruit consumption is sabotaging some people’s fat loss goals. It is counter productive when filling the liver with a direct glucose supply that turns off fat burn. Excessive amounts will not help and create further decline in personal metabolic health. Losing fat with compromised metabolic health is like trying to burn more fuel with a smaller engine. Juicing fruits daily would be an example of excessive fruit consumption.

If you are interested in replenishing glucose supplies in your muscles after a hard fat loss workout, I would recommend you stick to starches and avoid things with fructose in them. I personally have a little bit of rice after my harder workouts these days, but before I hit my body fat goal I used to only have avocados and veggies as carbs in my post workout meals. This was to ensure I did not put any unwanted amounts of glycogen into my liver that would turn off fat burning.


Tips & Takeaways:

  • Starches, Dextrose / Glucose are best for pre-workout and fructose should be avoided since it can not be used for energy right away. Fructose will also take energy away from your workout through digestion needed to convert it to fuel.
  • Starches, Dextrose / Glucose are also better for post workout as you are most interested in replenishing muscle glycogen stores and fructose doesn’t help with this.
  • Alternatively glutamine, a branch chain amino acid supplement can be used to replenish glucose stores in muscles without spiking insulin and without creating unwanted excess glucose to store in the liver. This will allow you to recover your muscles quicker and stay in fat burn. [11]
  • Sometimes foods have a lower GI (glycemic index) because they have fructose in them. Low GI is only a good thing when its a fructose free low GI food.


Click for References:


Note: If you read something in this article that you whole heartily disagree with based on scientific empirical evidence, please share it with me here. I’m always interested in appending and updating my information to be as accurate as possible for my readers.

Also contact me if there is anything you would like me to expand on or write about as it applies to your personal situations.





    Naturally occurring fructose in fruit is part of a complex of nutrients and fiber that doesn’t exhibit the same biological effects as the free high fructose doses found in “corn sugar”.

    1. Chris MacSweyn (Post author)

      100% agree! It is however on a spectrum right. The less fructose the better. Fruit is better than candy and vegetables are better than fruit. There are no benefits to ingesting fructose as far as I have researched.


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