3

votes

Is there any advantage from fructose over glucose for an active person?

Answered on August 19, 2014
Created April 11, 2011 at 5:03 PM

I began working with my dad a couple weeks ago in a plant nursery, where we are on our feet for 9-10 hours hauling heavy plants back and forth the whole day. I am amazed at how resilient my dad is compared to me. He relies on fruit throughout the day while I eat lots of starches (yams, sweet potatoes, taro), yet I find myself giving out way before he does. Could the fructose in the fruit he is consuming have any sort of metabolic advantage over glucose when it comes to restoring glycogen?

667f6c030b0245d71d8ef50c72b097dc

(15976)

on April 12, 2011
at 02:13 PM

Also, if the father's fuel source were to disappear for a day or even just a few hours how would he fare? How would a well-acclimate fat-burner fare in relative comparison then?

742ff8ba4ff55e84593ede14ac1c3cab

(3536)

on April 11, 2011
at 07:17 PM

No doubt about that, my dad is a work horse, but I'll experiment with fruit and see if there is any difference.

742ff8ba4ff55e84593ede14ac1c3cab

(3536)

on April 11, 2011
at 07:16 PM

Excellent plausible explanation.

A968087cc1dd66d480749c02e4619ef4

(20436)

on April 11, 2011
at 06:00 PM

Really good point.

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7 Answers

4
Cf626d3fba66c18297b3f1116a920e58

(3417)

on April 11, 2011
at 06:46 PM

Good thought, but no, the fructose is not at all what is allowing your dad to embarrass you all day.

An equal amount of fructose and glucose/glycogen ingested will result is vastly different amounts and methods of sugar metabolism in the liver. Almost all of the fructose will enter the liver, and much of it will be converted into VLDL (atherosclerotic), uric acid (hypertensive), and fatty acids (adipogenic and increases serum triglycerides). Some will enter the mitochondria and ultimately form ATP -- noticable energy.

The glucose will enter the liver at about a fifth the concentration as the fructose because its entrance is mediated by a hormone, insulin (a lack of a fructose transport mediating hormone like insulin may suggest that we have no business consuming it in even moderate amounts, but I like apples too much to follow that avenue). Because of the fundamentally different nature of glucose, an aldose, from fructose, a ketose, moderate glucose will NOT lead to significant VLDL, uric acid, and TAG production.

This is true of pure glucose (or polymers like starch) or of high-fructose chemicals like sucrose (50% fructose) or HFCS (actually only ~55% fructose, about the same as sucrose... hmm...). Actual foods are more complicated and have a lot more moving parts, and that's why this is a tough question to answer.

Now, add fiber into the mix, and things get more complicated as it has an effect on insulin production and satiety at a few levels. It may be that you are consuming too much starch, and your insulin system is overcompensating on the blood sugar increase. You may be experiencing pre-Paleo blood sugar crashes. Alternatively, the fiber content of the apples relative to the digestible sugar content could be significantly higher than that of the starchy foods you're eating. I don't know at all off-hand if that's the case. If it were, then the fruit fiber could mediate the sugar intake such that not too much is entering your dad's bloodstream -- not enough to cause a blood sugar crash but enough to provide him with energy.

Remember that a lot of things we can do in the Neolithic are totally novel, and our bodies respond in accordingly ridiculous ways. Although you may be supplying your cells with more energy by eating starch than your father is eating fruit, YOU feel exhausted because your blood sugar is low, a potent fatiguing signal.

Everything from the fiber part thereafter is just conjecture, but that's my best guess. Any other thoughts?

742ff8ba4ff55e84593ede14ac1c3cab

(3536)

on April 11, 2011
at 07:16 PM

Excellent plausible explanation.

3
1cbb6b2a813475d6c0b17fd5e898dc50

on April 11, 2011
at 05:56 PM

I work construction...very hard physical labor. I don't eat breakfast and eat about a pound of meat(hamburger,pork) for lunch. How can I work 9-10 hours a day without fructose or glucose? I'm not saying I don't ever eat any but I surely....nor should anyone, "rely" on fructose or glucose to get through the day. The only way to know whether or not anything is true is to live it! Learning is good but knowledge is applying.

A968087cc1dd66d480749c02e4619ef4

(20436)

on April 11, 2011
at 06:00 PM

Really good point.

2
5de2fffda92c0bf2be7ede10cad55546

(1781)

on April 12, 2011
at 04:40 AM

I think it's a mistake to rely on carbs for sustainable energy this way as the body can only hold an hour or two's worth at a time. I much prefer to rely on fat for my long term energy needs. I often go all day heavy pick and shovel work fully fasted or if needed, a big slurp of cream for lunch gets me through the day. As always, YMMV.

2
A968087cc1dd66d480749c02e4619ef4

(20436)

on April 11, 2011
at 05:27 PM

I would suggest that he is better adapted to the work than you are. He's been doing it a long time and it's only two weeks for you.

But try some fruit for a day or three and see if it makes a difference. Then go back to the tubers and see if you lose performance. only way to know for sure and I'd be interested in your n=1 experience.

It may be that fructose is replenishing liver glycogen better than glucose - and less glucose means less insulin with all its cascading effects.

I'm guessing he could switch to tubers while you switch to fruit and he'd still outperform you...

742ff8ba4ff55e84593ede14ac1c3cab

(3536)

on April 11, 2011
at 07:17 PM

No doubt about that, my dad is a work horse, but I'll experiment with fruit and see if there is any difference.

1
1e24731412133d02d1492bddf7a32c6e

on April 12, 2011
at 02:05 PM

I work in the oilfiels and see people who rely on sugars and starches for energy.They need to constantly replenish themselves and often have difficulty maintaining an even keel. Myself I have become a fat burner and can actually go all day without eating anything and not have a problem. I seriously doubt anyone putting out work at less than Olympic caliber training needs any large amount of starches or sugars to perform. If you have a low insulin level, due to not eating lots of sugars like your Dad or starches like yourself, you can easily burn body fat for energy throughout the day. Being able to do that is liberating.

1
05055dcbf12c81f1cce777ec365870af

(1791)

on April 11, 2011
at 05:11 PM

i'd be interested to know other things like, does he have a shorter fuse than you do? more mood swings of some kind? how is his ability to communicate while doing hard work? how old is he compared to you and how long has he been doing hard labor jobs? what is his physical condition and nutrition since birth compared to yours?

667f6c030b0245d71d8ef50c72b097dc

(15976)

on April 12, 2011
at 02:13 PM

Also, if the father's fuel source were to disappear for a day or even just a few hours how would he fare? How would a well-acclimate fat-burner fare in relative comparison then?

0
5bbc8269614897ecebdd73b6eb0686e2

(0)

on April 29, 2013
at 01:07 AM

Hi I am not educated on a chemistry side of this problem. But! I am a cyclist and I also have quite a big garden to work. In summer it is very exhausting. And riding bike at 100F+ too! My remedy is vinegar(known from old Roman time as 1 absolutely necessary ingredient for field workers) Occasionally I start my day wit 1 lemon squeezed out,about 1-2 spoon of apple cider vinegar,good pinch of salt and 2 spoons of olive oil(to prevent stomach walls from being attacked by the acids). No food for 10-15 minutes after that. Then through out the day I would have couple of tees(black or green or half and half) with 1-2 spoons of apple cider vinegar and sugar. Every day! That somehow regulates the kidneys,prevents kidney stones,great digestion of any food and a lot of energy. I can go on for 50-70 miles in 100F+ sunny day on mi bike,where a lot of other people would die in 5 miles. Of course, the training is also helpful - i.e. getting used to it....(as your old man doing his labor all the time....)

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