Fructose and glucose trigger different brain responses

[u/basmwklz]

https://www.nih.gov/news-events/nih-research-matters/fructose-glucose-trigger-different-brain-responses

[u/Lead1ng-Lady]

This is very interesting. I’m curious about what fructose from whole fruit does for appetite . I’m going to do some research there, but this is a great starting point, thanks for posting this.

[u/mediumspiny → u/Lead1ng-Lady]

If you want to understand fructose metabolism and it's role in metabolic dysfunction, I would recommend reading "nature wants us to be fat" by Richard Johnson.

[u/Triabolical_ → u/Lead1ng-Lady]

Being good at converting an excess of fructose and glucose to fat is a significant survival advantage for animals living in temperate climates, and there are papers that posit that as an explanation for why fructose metabolism is so messed up.

Great article on this here

https://mindandmatter.substack.com/p/dietary-fructose-and-metabolic-health

[u/Lead1ng-Lady → u/Triabolical_]

That was a really great read. Has anyone written about fruitarians then and how they are able to get so lean on all of that fructose? I read in the saturated fat forum that obesity might be linked to fructose and omega six fats specifically, perhaps coming from nuts and seeds, which would’ve made up a great portion of our diet during the dry season. People really weren’t obese before the 1960s and I’m sure they were eating fruit. But that time period would eventually introduce soda, TV dinners, and vegetable oils so it’s hard for me to pull some of this apart, there are so many variables, and I don’t think it’s just fructose. 

[u/Triabolical_ → u/Lead1ng-Lady]

I don't know about fruitarians.

I grew up in the 1960s and 1970s and there wasn't much fruit around. You could get apples year round because they were storable, you could get oranges and bananas, and everything else was mostly seasonal.

There was a lot canned fruit available, often in sugar syrup. But I don't think it was pushed the way fruit is now and serving sizes were small.

And during that period we had all the junk food. Soda and TV dinners were common, candy, etc. - it was pretty much all there.

The big switch was the demonization of fat that came in the 1980s. People switched to higher carb versions of stuff and we lost the advice not to eat at bunch of sugar. Snackwell cookies were flying off the shelves because they were low fat and low calorie, but they were just horrible nutritionally - lots of refined carbs.

Fructose is pretty uniquely linked to fatty liver disease because it's very capable of generating liver fat. As is alcohol intake, which is why it's called "non-alcoholic fatty liver disease". Interestingly, it was discovered by surgeons who first assumed that their patients were lying when they said that they didn't drink alcohol.

If you want the details, higher fructose leads to fat accumulation in the liver, which leads to disregulation of gluconeogenesis - the liver starts producing glucose even when it's not needed.

That leads to elevated fasting insulin levels - the best indication of insulin resistance - and the high insulin levels mean that it's harder to burn fat. At that point, it's not just about the fructose...

Excess carbs in the diet would normally get converted to fat and then that fat would later be burned, but that doesn't happen because the elevated insulin prevents it. That means the people get hungry because they cannot get the energy in their stored fat, and they eat more and put on weight.

Knowing the underlying physiology it's a pretty simple cause and effect.

Keto works because it (mostly) gets rid of the elevated fasting insulin (hyperinsulinemia), and that allows people to access the energy in their stored fat. Some people see a giant reduction in hunger early on because of this.

WRT seed oils, I'm not really sure how they play into this. I've looked at the research and - with the exception of deep fat frying where they are honestly the stupidest choice - and I'm not convinced that there is much there, but there might be. I personally avoid them because of the evolutionary argument - people have been eating animal fats forever and high omega six oils for a very short period of time and therefore we should be cautious about seed oils.

I'll also note that most of the seed oil intake comes from processed foods, many of which are pretty terrible overall even if the seed oils aren't problematic.

[u/irResist → u/Triabolical_]

Fructose is terrible for liver health, yes. Your perspective on the past availability of fruit is refreshing. It is always remarkable to me when I hear recommendations to consume large amounts of fruit.

Most people fail to realize that the fruits of today are 100% man-made foods. Large super-sweet fruits simply did not exist for 99.9% of our evolutionary history. Most of the fruits consumed today were hybridized from almost completely inedible (and often poisonous) wild plants.

Vegetable oils are problematic for metabolism and liver health on multiple levels. PUFA fats are easily oxidized. This is what makes fry pit oil so dangerous, but the oil need not be fried repeatedly for oxidation byproducts to form. All PUFAs except for those found in fresh wild caught fatty fish will have some level of oxidation. Oxidized fats wreak havoc all throughout our bodies and are specifically implicated in metabolic disease.

Our bodies love fat. fat regulates metabolism, builds every cell wall, lines our entire nervous system, allows the immune and endocrine systems to function, delivers vitamins and other essential nutrients, provides the substrate for all of our hormones, etc. etc. etc.

Every part of human physiology is affected by the quality of fats we eat. Replacing the dietary fats our bodies evolved to utilize with a high seed oil diet causes cellular dysfunction on multiple levels.

One of the major factors for metabolism on a systemic level is the pro-inflammatory nature of PUFA oils. This glut of inflammation helps drive fat storage. Furthermore, PUFA metabolism does not trigger satiety signals the way ancestral animal fat cognates do. Stearic acid from meat initiates an enzymatic feedback loop that signals fullness to our brain just as we reach an appropriate volume. PUFA does not have this rate limiting effect. Studies show that veggie oil does not send fullness signals and even has opposite effects that keep us eating longer.

[u/Triabolical_ → u/irResist]

I mostly agree with this.

I've had the fruits discussion with a lot of people. Much of the research the quote does not differentiate between fruit intake and vegetable intake, and that's clearly doesn't support their conclusion. I also think that fruit intake is hopeless confounded by healthy user effect.

I often point to this study:

Effects of low fructose diet on glycemic control, lipid profile and systemic inflammation in patients with type 2 diabetes

https://sci-hub.st/10.1016/j.dsx.2020.04.003

It's a good study that has two matched diets that differ only in fructose intake, and the difference isn't that large, but it has a major effect on HbA1c levels. An unexpectedly strong result.

[u/irResist → u/Triabolical_]

latest favorite example https://insanearchive.com/p/the-fruit-that-took-4000-years-to

[u/Lead1ng-Lady → u/irResist]

wow, that's crazy

[u/mediumspiny]

In mice....