Health Outcomes Of A High Fructose Intake: The Importance Of Physical Activity

Mito

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Abstract
Fructose metabolism is generally held to occur essentially in cells of the small bowel, the liver, and the kidneys expressing fructolytic enzymes (fructokinase, aldolase B and a triokinase). In these cells, fructose uptake and fructolysis are unregulated processes, resulting in the generation of intracellular trioses‐phosphate proportionate to fructose intake. Trioses‐phosphate are then processed into lactate, glucose, and fatty acids to serve as metabolic substrates in other cells of the body. With small oral loads, fructose is mainly metabolized in the small bowel, while with larger loads fructose reaches the portal circulation and is largely extracted by the liver. A small portion however escapes liver extraction and is metabolized either in the kidneys or in other tissues through yet unspecified pathways. In sedentary subjects, consumption of a fructose‐rich diet for several days stimulates hepatic de novo lipogenesis, increases intrahepatic fat and blood triglycerides concentrations, and impairs insulin effects on hepatic glucose production. All these effects can be prevented when high fructose intake is associated with increased levels of physical activity. There is also evidence that, during exercise, fructose carbons are efficiently transferred to skeletal muscle as glucose and lactate to be used for energy production. Glucose and lactate formed from fructose can also contribute to the re‐synthesis of muscle glycogen after exercise. We therefore propose that the deleterious health effects of fructose are tightly related to an imbalance between fructose energy intake on one hand, and whole‐body energy output related to a low physical activity on the other hand.

Modulation of fructose metabolism by fructose intake and muscle energy output. In conditions of low fructose intake (Abstract figure A), available data suggest that fructose is primarily metabolized in the gut and, to a lesser extent, in the liver. Fructose metabolized in these organs then recirculates as glucose and lactate intermediates to be distributed to the periphery. With increasing fructose intake (Abstract figure B), intestinal fructose metabolism becomes saturated and fructose is mostly extracted by the liver where it is still converted into metabolic intermediates. When total energy output is high, fructose conversion into glucose and lactate remain the preferred, most energy‐efficient disposal routes as both intermediates can provide energy to working muscle. When total energy output is low (Abstract figure C), however, the mismatch between fructose input and energy output forces the diversion of some fructose into lipids. According to this model, fructose deleterious effects on health would only appear in conditions of chronically high fructose intake associated with low physical activity. IHCL: intrahepatocellular lipids; TRL‐TG: triglycerides in triglycerides‐rich lipoproteins.

https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP278246#.XOeTgLlZR_M.twitter
 

LiveWire

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Thanks.

Very sober answer to the eternal black and white question is fructose good or bad.
 

olive

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Matches my experience. Fructose consumption should be directly tied to physical activity level. Small amount of fruit upon waking to replenish liver glycogen, then fruit only upon compeltion of exercise. Fructose has the benefit of increasing muscle glycogen uptake, so its especially beneficial after weightlifting/calisthenics.
 

yerrag

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Perhaps my recent weight gain could be traced to increased fruit consumption. I wanted to increase potassium intake and chose to increase intake of fruit juices, from juicing fruits. Where previously I was able to stay in shape even without having to force myself to exercise strenuously, I wasn't able to do so lately as I gained weight and I find it harder to fit into my pants. I should perhaps shift to vegetable juicing to get my fill of potassium. However, my blood sugar drops and I feel hungry or sleepy shortly after drinking vegetable juices. And it's because vegetable juices are largely free of sugar and full of potassium, and potassium facilitates glucose uptake by tissues. So, I should try adding sugar, in the form of glucose, to my vegetable juices. I'll add maltose to my vegetable juices and see how it goes. It won't taste as sweet as putting cane sugar though.

Either it's the fruit juice, or the milk, which I've added to my daily food consumption as part of folowing Peat's food choices. But I think it's the fruit juices that's causing my weight gain.

Nice article. Thanks!
 

yerrag

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Why not add fruit into the veggie juice instead of sugar?
For the same reason I'm not fruit juicing - fructose. But you're right - I could put some, just enough that the fructose isn't that much. Maybe if the sugar component is 25% fructose and 75% glucose, it could work.
 

yerrag

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Mauritio

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I loose weight and get softer hair from fructose but also feel lower testeron-ish from fructose... Go figure...
 

lampofred

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All this is saying is that if you eat more fructose than you can metabolize, it will turn into fat and triglycerides. Dr. Peat says the fat from converted sugar is actually anti-inflammatory and protects against stored PUFA, and he says triglycerides aren't bad for you, they are just a sign of stress.

To me it seems like this is a problem with eating too much for your metabolism, not a problem with fructose itself.
 

Cirion

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Either it's the fruit juice, or the milk, which I've added to my daily food consumption as part of folowing Peat's food choices. But I think it's the fruit juices that's causing my weight gain.

It's the milk. As I increase my fructose/sugar to starch ratio, I find it easier not harder to avoid gaining weight. Milk is a problem for me and many others here. My experience shows that fructose does not readily turn into body fat... as long as dietary fats (PUFA's in particular) are sufficiently low.

BTW, I am quite sedentary.
 

Vinny

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Abstract
Fructose metabolism is generally held to occur essentially in cells of the small bowel, the liver, and the kidneys expressing fructolytic enzymes (fructokinase, aldolase B and a triokinase). In these cells, fructose uptake and fructolysis are unregulated processes, resulting in the generation of intracellular trioses‐phosphate proportionate to fructose intake. Trioses‐phosphate are then processed into lactate, glucose, and fatty acids to serve as metabolic substrates in other cells of the body. With small oral loads, fructose is mainly metabolized in the small bowel, while with larger loads fructose reaches the portal circulation and is largely extracted by the liver. A small portion however escapes liver extraction and is metabolized either in the kidneys or in other tissues through yet unspecified pathways. In sedentary subjects, consumption of a fructose‐rich diet for several days stimulates hepatic de novo lipogenesis, increases intrahepatic fat and blood triglycerides concentrations, and impairs insulin effects on hepatic glucose production. All these effects can be prevented when high fructose intake is associated with increased levels of physical activity. There is also evidence that, during exercise, fructose carbons are efficiently transferred to skeletal muscle as glucose and lactate to be used for energy production. Glucose and lactate formed from fructose can also contribute to the re‐synthesis of muscle glycogen after exercise. We therefore propose that the deleterious health effects of fructose are tightly related to an imbalance between fructose energy intake on one hand, and whole‐body energy output related to a low physical activity on the other hand.

Modulation of fructose metabolism by fructose intake and muscle energy output. In conditions of low fructose intake (Abstract figure A), available data suggest that fructose is primarily metabolized in the gut and, to a lesser extent, in the liver. Fructose metabolized in these organs then recirculates as glucose and lactate intermediates to be distributed to the periphery. With increasing fructose intake (Abstract figure B), intestinal fructose metabolism becomes saturated and fructose is mostly extracted by the liver where it is still converted into metabolic intermediates. When total energy output is high, fructose conversion into glucose and lactate remain the preferred, most energy‐efficient disposal routes as both intermediates can provide energy to working muscle. When total energy output is low (Abstract figure C), however, the mismatch between fructose input and energy output forces the diversion of some fructose into lipids. According to this model, fructose deleterious effects on health would only appear in conditions of chronically high fructose intake associated with low physical activity. IHCL: intrahepatocellular lipids; TRL‐TG: triglycerides in triglycerides‐rich lipoproteins.

https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP278246#.XOeTgLlZR_M.twitter
Thank you
 
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What is that supposed to mean?
If it means that the liver is using less of other materials( protein) to produce glucose, then it means less by products such as ammonia, and less catabolism of lean tissue, but to be honest I'm not sure if that's what they were trying to convey by saying that.
 
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Perhaps my recent weight gain could be traced to increased fruit consumption. I wanted to increase potassium intake and chose to increase intake of fruit juices, from juicing fruits. Where previously I was able to stay in shape even without having to force myself to exercise strenuously, I wasn't able to do so lately as I gained weight and I find it harder to fit into my pants. I should perhaps shift to vegetable juicing to get my fill of potassium. However, my blood sugar drops and I feel hungry or sleepy shortly after drinking vegetable juices. And it's because vegetable juices are largely free of sugar and full of potassium, and potassium facilitates glucose uptake by tissues. So, I should try adding sugar, in the form of glucose, to my vegetable juices. I'll add maltose to my vegetable juices and see how it goes. It won't taste as sweet as putting cane sugar though.

Either it's the fruit juice, or the milk, which I've added to my daily food consumption as part of folowing Peat's food choices. But I think it's the fruit juices that's causing my weight gain.

Nice article. Thanks!
I strongly think it's the milk that is causing your weight gain. My father stopped drinking milk for just a week, and he was visibly leaner! After he started drinking it again, he went back to his old self. I've been eating a ton of sugar everyday for pretty much 2 years now and I'm definitely not fat( even taking cypro and niacinamide). I do make up for the lack of micronutrients in white sugar, so maybe that is an important part of the puzzle as well.
 

Kartoffel

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If it means that the liver is using less of other materials( protein) to produce glucose, then it means less by products such as ammonia, and less catabolism of lean tissue, but to be honest I'm not sure if that's what they were trying to convey by saying that.

I doubt this is what they are saying. The papers on fructose are full of these non-sensical statements.
 

yerrag

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It's the milk. As I increase my fructose/sugar to starch ratio, I find it easier not harder to avoid gaining weight. Milk is a problem for me and many others here. My experience shows that fructose does not readily turn into body fat... as long as dietary fats (PUFA's in particular) are sufficiently low.

BTW, I am quite sedentary.

I strongly think it's the milk that is causing your weight gain. My father stopped drinking milk for just a week, and he was visibly leaner! After he started drinking it again, he went back to his old self. I've been eating a ton of sugar everyday for pretty much 2 years now and I'm definitely not fat( even taking cypro and niacinamide). I do make up for the lack of micronutrients in white sugar, so maybe that is an important part of the puzzle as well.

The reason why I think it's too much fructose is because my triglycerides went from 87, as I was just starting with this forum, and it went up to 222 mg/dL the last time I checked, 3 months ago. In the same span, my cholesterol went up as well, though not ad dramatically, from 210 to 234.

I think it had more to do with fructose than with milk, but I'm not sure. What do you think?
 
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The reason why I think it's too much fructose is because my triglycerides went from 87, as I was just starting with this forum, and it went up to 222 mg/dL the last time I checked, 3 months ago. In the same span, my cholesterol went up as well, though not ad dramatically, from 210 to 234.

I think it had more to do with fructose than with milk, but I'm not sure. What do you think?
The increase in cholesterol is likely beneficial. Low levels of cholesterol and dementia seem to have a relation. Fructose stimulates insulin very weakly, causing less activation of the lipoprotein lipase enzyme, which means triglycerides stay in the blood instead of being sent to the fat tissues. Ray has said that triglycerides are harmless and usually a sign of stress/ overfeeding. I feel like they are attacked by mainstream media for the same reasons cholesterol is: associations and no causation. A study in rats showed triglycerides increase resistance to endotoxins, so they can't be all bad. As far as I know, skeletal muscles like to burn triglycerides, especially when they are contracting, so walking and lifting weights would be good for lowering triglycerides. Also, although fructose is known to increase triglycerides and cholesterol, it tends to not cause weight gain, so that's why I think it's the milk.

How are you feeling, compared to when you started implementing Peat's ideas?

Have you tried doing a low fructose diet for a month or two to see if you lose weight? If that doesn't work, you can introduce fructose back in and eliminate milk for a similar period of time and see if that has any impact.
 

yerrag

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The increase in cholesterol is likely beneficial. Low levels of cholesterol and dementia seem to have a relation. Fructose stimulates insulin very weakly, causing less activation of the lipoprotein lipase enzyme, which means triglycerides stay in the blood instead of being sent to the fat tissues. Ray has said that triglycerides are harmless and usually a sign of stress/ overfeeding. I feel like they are attacked by mainstream media for the same reasons cholesterol is: associations and no causation. A study in rats showed triglycerides increase resistance to endotoxins, so they can't be all bad. As far as I know, skeletal muscles like to burn triglycerides, especially when they are contracting, so walking and lifting weights would be good for lowering triglycerides. Also, although fructose is known to increase triglycerides and cholesterol, it tends to not cause weight gain, so that's why I think it's the milk.

How are you feeling, compared to when you started implementing Peat's ideas?

Have you tried doing a low fructose diet for a month or two to see if you lose weight? If that doesn't work, you can introduce fructose back in and eliminate milk for a similar period of time and see if that has any impact.
I'm glad to know it isn't a large concern to have high triglycerides. That more than anything its reflective of a perfect storm of high fructose intake and a relatively sedentary lifestyle. And that high triglycerides isn't necessarily associated with weight gain.

Perhaps it's also because I tend to spend time reading the forum and its links that I've become more sedentary, and that's why my weight gain can be easily blamed on being peaty. I had been more active when I didn't have the need to catch up with the endless reading "homework" the forum gives me, especially from haidut and from amazoniac. And long threads play a good part also, even if I'm just reading. It's also that I start a few threads now and then, and the time spent in preparing even a minor topic isn't trivial either.

So I can't blame it on milk just yet. And since I haven't replaced my broken scale for a while, I don't really get any warning until my pants starts to tighten lol.

But I've begun drinking less fruit juice already, so I should feel the effect in a month if it's from fructose. The problem is I've begun also to reduce my milk intake. We'll see where this goes. It used to be so easy to just lose weight before. Now, it's harder. Maybe it's also because I'm not getting any younger.

p.s. I noticed that when my heart rate has slowed down before, and saw my weight increase. When my heart rate increased, my weight would decrease and I had gone from not needing a belt to needing one. Lately, my heart rate has gone down as well, so it may just be a matter of getting my heart rate to increase. Yesterday, I noticed a large uptick in heart rate from taking 2 teaspoons of stearyl alcohol.

Does drinking milk lower metabolism I wonder?

Oh yes, I think since Peating I've become free of my frequent allergic rhinitis. I think once I got above a certain threshold of metabolism, I've become impervious to pollen or anything that's allergenic to my respiratory pathway.

But last year I had a month-long dry cough that just wouldn't go away. When I found out that it was poor acid-base balance that was lowering my metabolism, I found the cause of it and that prompty set my metabolism to improve. And I got rid of my cough. I guess I'm able to connect the dots now and that has put me more in control of my health.
 
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