October Challenge: Tackle Fructose Head On!

A Personal 31-Day Challenge to Reduce Fructose Intake

Don’t Go Bananas On Your Fruit Intake!

Since reading Robb Wolf’s The Paleo Solution almost 3 years ago I have been living a “Paleo” lifestyle as close as I possibly can (the sleep part is still tough due to being a Ph.D. student, school often times keeps me from getting the sleep I would like).  I have had incredible success and can’t begin to thank the entire Paleo community for their selfless dissemination of knowledge.   I have gone from 180 lbs at 15% body fat to around 168 pounds at 6% body fat, increased my strength in virtually every domain, and improved some long-time health issues.

What does this have to do with today’s post? Well, along with the rest of the “paleo” community, I am going to purpose my own challenge for myself and see how many of you I can get onboard to join me. Let’s cut out fruit (specifically fructose) for 30 days and see how our body changes. To steal Robb Wolf’s mantra “Try it for 30 days and see how you look, feel, and perform”.

So here is the challenge. Starting October 1st, I am cutting out all fruit, and fructose containing sweeteners. My carbohydrate sources are going to be roots, tubers, and squash based vegetables. I am also going to document my progress along the way and I encourage you all to do the same.  On October 1st I will record my weight (just as a baseline, I am not a scale person and actually encourage people not to weigh themselves all that frequently), BF% (using either a BOD POD or calipers, whichever I can most easily access), a measurement of my umbilicus,  and take pictures.  On November 1st I will do the same thing and report the findings.  Along the way I will be blogging about my experience and sharing it with you along the way.


Anyone can join me in the October fructose challenge and I invite ALL of you to join in. Take your measurements before you start and after you finish and tell me about your experience. I am going to give away a prize to the person who submits the best post about their experience and how it changed their life!

You have 2 weeks to get your fruit in (I mean it is prime peach and apple season right now so I have to let you get those delicious treats in now while you can) and prep yourself for October.  Don’t think I will be leaving you to figure the culinary stuff out for yourself either; I’ll be posting recipes and links to my favorite Paleo-friendly squash loving cooking sites along the way. I would also love to hear your feedback along the way.

So why exactly am I cutting out fruit for 30 days? First off, I do not believe fruit is horrible,and that in an isocaloric or hypocaloric diet I believe it can do a lot of good (especially when compared to other, processed carbohydrate sources). That being said, there is a dark side to fruit and its native sugar, fructose. The rest of this post is a brief overview to this darker side of fruit.

Lets begin with a basic, general review of fructose and how it is metabolized in the body.  Like glucose, fructose is a monosaccharide (simple sugar). Both glucose and fructose have the same basic chemical makeup (C6H12O6); however, their molecular arrangement differs.  In geek speak, that means fructose is an isomer of glucose.


GLUCOSE                                               FRUCTOSE

This simple structural difference gives fructose its sweet taste, more important it alters how it is metabolized by the body.  Glucose can be metabolized in various tissues in the human body, whereas fructose metabolism is almost solely confined to the liver.

Are the wheels in your head started to turn yet…. Two sugars… one can be processed throughout the body and one in the liver…… If you think this effects how much fructose compared to glucose we can actually process due to the size and capacity of a liver vs. the rest of the human body you’re brain is on the right track!

A large portion of humans are unable to completely absorb doses of fructose in the range of 20-50g.  This is due to mainly two main reasons.  The first as previously alluded to is the fact that the liver, like all organs, has only a limited capacity to process substrates.  The second reason is that during exercise,(in a healthy, normal individual) the liver glycogen is utilized for energy after blood glucose and muscle glycogen are unable to keep up with metabolic demands via a hormone glucagon.  Thus, liver glycogen is rarely ever completely depleted and typically only needs to be “topped” off post exercise.

We now know that Fructose can only be metabolized in the liver. In the liver’s defense, it is quite the organ and can process a decent amount of glucose but it gets full quickly; however, it was not biologically designed to handle abnormally large amounts of fructose that we currently subject ourselves to (i.e. the devil that is HFCS, or even throwing 3 bananas and 2 cups of pineapple juice into a blender for a “healthy smoothie”).

Ok……… so what exactly does this mean? Why is too much fructose that bad? What happens when we subject the liver to this much fructose? When the liver tops off its glycogen stores it has to make something else with all the “wonderful” fruit sugar we took in. The liver turns this excess fructose into a saturated fatty acid known as palmitic acid and sends them into the bloodstream as triaglycerols.

Palmitic acid in the bloodstream is extremely effective in crossing the blood-brain barrier…. Yup, that’s right, Those 3 bananas and pineapple juice turned into saturated fat and went directly for the think tank.  Once in the brain palmitic acid has a nasty little trick up its sleeve, it pulls a once over on your hormone signaling for insulin (the dreaded insulin resistance!) and leptin (an appetite hormone that regulates food (energy) intake. Leptin disregulation has been shown to lead to over eating and changes in weight and body composition.

Fatty liver, scrambled brain function, appetite deregulation…. This all sounds pretty bad doesn’t it? Unfortunately I have to drop one more bombshell. After insulin resistance in the liver sets in, the liver goes haywire.  Normal hormone responses that regulate glucose release from the liver stop functioning, it begins spewing out glucose like a volcano.  This “spewing” of glucose, insulin, and triglycerides stimulates your fat cells (adipocytes) to store fat.  Not only that but we have excess blood glucose levels which ultimately leads to type II diabetes.

Where does this leave us? Too much fructose causes insulin resistance, leaves us with a deranged endocrine system, and blood glucose levels your doctor would be seriously worried about. Are you freaked out yet? Are you re-evaluating your idea of fruit?  Don’t freak out, that isn’t my intent, and I will remedy that situation in just a second. So I have, in essence, vilified fruit. For that I apologize, I just want to inform you of what exactly happens when you ingest obscene amounts fructose.

Fruit, in moderation, is an excellent source of micronutrients (vitamins and minerals) and is a superior source of carbohydrate when we compare it to any of the grains or legume counterparts. As I mentioned earlier, your body can safely handle between about 20-50g of fructose in a given day.  That is actually a lot of fructose when you put it into the context of REAL FOOD, not the processed HFCS or other sweeteners that contain fructose (agave, honey, etc.). For example, you could eat 2 apples or 2 pears in a day and still fall in that range.

           Here is a break down of the average fructose contents of typical fruits.


By this point I know you all are going to ask, “Ok, so no grains, no dairy, no legumes, now no fruit! Where am I going to get my carbohydrates”? Well, too be honest I timed this post/challenge this time of year for this exact question. We are at the perfect time to switch out all those carbohydrate choice for (in my opinion) the best carb based food on earth. SQUASH!!!!


Squash, specifically the fall and winter varieties are packed full of healthy, low glycemic carbs, have incredible micronutrient profiles, are amazingly versatile, and can last for weeks in your fridge.    Some of my favorite squash varieties are spaghetti squash, acorn squash (had some tonight for dinner, baked and sprinkled with cinnamon and coconut oil), pumpkins, and butternut squash.

(If you want a head start here is an amazing Paleo Lasagna Recipe )

For more information on fructose and how it is metabolized, check out the following resources

Basciano, H., Federico, L., & Adeli, K. (2005). Fructose, insulin resistance, and metabolic dyslipidemia. Nutrition and Metabolism , 2 (5), 1-14.

Gropper, S. S., Smith, J. L., & Groff, J. L. (2005). Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth.



Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Examine.com - A Look into the Surprising Elements of Supplements

An Evolutionary Approach to Health, Nutrition, and Fitness

Evolutionary Health Perspective

An Evolutionary Approach to Health, Nutrition, and Fitness

The Daily Lipid

An Evolutionary Approach to Health, Nutrition, and Fitness

Whole Health Source

An Evolutionary Approach to Health, Nutrition, and Fitness

Chris Kresser

Let's take back your health - Starting Now.

Catalyst Athletics: Olympic Weightlifting

An Evolutionary Approach to Health, Nutrition, and Fitness

PaleOMG – Paleo Recipes

An Evolutionary Approach to Health, Nutrition, and Fitness


An Evolutionary Approach to Health, Nutrition, and Fitness

Evolutionary Health Perspective

An Evolutionary Approach to Health, Nutrition, and Fitness

%d bloggers like this: