How the Brain Uses Glucose to Fuel Self-Control

The body cannot convert fat into glucose at all.

Several studies have shown that endurance is equal w/ fat as the fuel. You do have to spend 4 or so weeks adapting though.

Here is a link to a summary, I couldn't find the actual research articles I was thinking of though.

http://www.pponline.co.uk/encyc/sports-nutrition-should-athl...

I have done exactly this, and it's been fine. I regularly ride centuries around the Bay Area on a sugar free diet.

Your body definitely needs time to adapt to a fat based diet, but it can satisfy all your energy needs.

I've also done centuries with sugary 'energy' foods. I frequently found myself having to pull over or dangerously balance in order to keep my blood sugar high by dosing myself every 45 minutes. Your stomach churns, your teeth feel awful, being constantly in service to your legs. Burning the fat is a much more comfortable proposition.

"Try doing a 100km bike ride on an up/down road circuit, with fat as the main fuel."

I am not an extreme endurance athlete, but I have heard multiple anecdotes of extreme endurance athletes eating cheese pizza slices during their 100-200 mile runs. It's actually a fairly common theme ...

ALSO: Do NOT meta-discuss your own downvotes. Don't interrupt the discussion to talk about the scoring.

I work construction, I managed eating a very strict ketogenic diet for several months. There's a brief window where your energy is low in the beginning, but after a month I found I had far more endurance than I did before, and than I have now since stopping the diet. My job performance not only improved, but I stopped eating lunch because I no longer needed to recover energy. (edit: an extra anecdote here, it's the only time since I was a kid that I've been hyperactive in the evening. It's also the only time I've actually wanted to exercise, and often times not only wanted to but had to otherwise I'd get insomnia due to my body feeling 'too awake'. I'd be making a cup of tea and doing jumping jacks waiting for the kettle to boil. I can't count the number of times I got out of bed to go work out because I couldn't sleep.)

Also, doing a 100km bike ride with fat as the main fuel would actually be exceptionally easy if you used the proper technique, because the entire purpose of the gearing system on racing bikes is to ensure your exertion remains the same. It would just require training with this goal in mind, like Timothy Oslon who's a successful ultramarathon runner.

> I suggest you actually go ahead and try it, before thinking you've formed any sort of informed opinion on the subject.

I would suggest you do the same, because you don't seem too well informed either.

Unfortunately, the link does not go into any detail and there is no reference to the source. I've heard about "apparent adaptations", but never specifics. So not sure they do exist.

Researchers who lived with the Inuit (Vilhjalmur Stefansson etc.) did not have any problems following the Inuit diet.

There has been some debate about the actual Inuit diet, specifically, about its carbs content. It seems that fresh and/or frozen flesh contains a significant amount of carbs (in the form of stored glycogen). This is a good review[1] of the whole thing.

[1] http://freetheanimal.com/2014/03/disrupting-carbs-prebiotics...

Great, we can just go ahead and file that in the garbage with the rest of the anecdotes. Notice how everyone who is happy with their diet says the same thing you just said, no matter what their diet is?

I also feel much more sharp on coffee. But as a heavy coffee drinker, pretty much every available study shows that I am just as sharp as I would be without the black stuff.

Turns out my own feelings about sharpness has absolutely nothing to do with congnitive ability. Who would have thought?

I had the same experience on a keto diet. There's also nothing like the euphoria of having so much energy after a long day (I work construction) that at 2am you have to get out of bed, still wide awake, and go down stairs to do a hundred push ups to burn off some energy.

In my case, ketosis was great to fix my metabolism and kickstart fat loss when I was overweight. However, after a couple of years in ketosis, I started to get some worrying symptoms (mainly brain fog and constipation).

Now I am eating about 200g/day of carbs (mainly from rice and veggies) and I feel much better. My weight remains the same.

This is a good intro to the potential problems of chronic ketosis [1].

[1] http://freetheanimal.com/2014/02/ketogenic-diets-news.html

> It is amazing how many people on HN really hate science.

Counterpoint: medical science is insanely difficult and expensive, due to individual variations in genetics and lifestyle, and the huge number of variables that it is effectively impossible to completely control for. This leads to research that is tainted by the incentives of those agents that afford the expense, and results that tend to be correlation more often than causation.

That's not to say that we should ignore the science we do have; rather, we shouldn't fall into the trap of assuming we can model biology as precisely as astrophysics. Sometimes the illusion of knowledge is more dangerous than ignorance.

Energy generation is much more efficient once you go through ketoadaptation. It involves fatigue like symptoms that can last up to several weeks during the transition though. But once you go through it, you feel quite amazing.

> It is amazing how many people on HN really hate science

Inflammatory language like this (as well as in https://news.ycombinator.com/item?id=8696794, https://news.ycombinator.com/item?id=8696817, and other comments you've posted) adds to the problem. Assuming you're 100% correct on facts, railing against perceived idiots merely impedes the communication of the facts. It discredits your arguments, and it poisons the discourse. We all need to edit this kind of thing out of the comments we post to HN.

I'm a Type 1 diabetic. No one in the medical field, and run I've run in to my fair share of idiots along the way, has ever told me to "eat candy" when my blood sugar is low. The medical advice is that I should ALWAYS keep glucose on my person in a liquid or tablet form in case of a low blood sugar as these will bring blood sugar back up the quickest.

If I do not have glucose on my person then I'm advised to drink anything that is "liquid sugar" - juice, pop, milk (lactose) because it raises the blood sugar quickly.

But you need to consider this is because our bodies are DEFECTIVE. When my blood sugar goes to 30 (been there, done that) I need a blood sugar spike RIGHT NOW. And by right now I mean before I pass out, slip into a coma, and DIE.

So when I am presented with a number so low that I am about to be seriously fucked, and I don't have my tablets with me, I'll eat every fucking carbohydrate in sight because a high blood sugar might kill me in 20+ years, but a low can kill me right now.

Outside of potentially LIFE THREATENING low blood sugar levels diabetics are encouraged to try to stay away from foods that fall into the high glycemic index categroy. This is because they raise blood sugar fast, and then they crash back down just as fast. This is what most of us diabetics refer to as the "Roller Coaster"; and we do not like coasters.

http://www.diabetes.org/food-and-fitness/food/what-can-i-eat...

The really great thing about healthy non-diabetics is your body is really good at self regulation, so your "lows" will likely never go below 70 (e.g. Not dangerous), and even after gorging yourself on an entire pizza and chasing it with a 2 liter bottle of Code Red Mountain Dew your body will still keep your blood sugar maxed at an also healthy 100.

So please don't talk like you understand diabetic science or that it in anyway relates to normal, healthy functioning adults. It is the equivalent of trying to say that someone without cancer should get chemo, because it helps people with cancer. It's not like you are going to pass out and die or possibly have your blood turn into acid and poison you to death (yes this is a real risk for a Type 1 diabetic http://www.diabetes.org/living-with-diabetes/complications/k... http://en.wikipedia.org/wiki/Ketoacidosis)

He means Ketones.

When you are eating excessive sugars and carbs like most people today, your body doesn't burn fat. You only use sugars for energy. That's why you have your energy levels constantly up and down.

I have been on ketagonic diet last 3 months. I eat no sugars and less than 50gr carbs. My energy levels are always stable now, lost 20lb. I don't need glucose for energy.

I see it as winter mode vs summer mode:

- If it's is summer there are sugars and carbs. So, your body keep storing as much fat as possible and uses carbs for energy and pushes you to eat as much as you can. Making you feel hungry all the time so you eat more and store more fat.

- if it is winter, there are nothing much to eat, so your body uses fat as energy.

The problem with modern world is that there are just so much food and carbs around us that we are always in summer mode.

It seems there is a pathway that converts lipids to glucose: http://www.ncbi.nlm.nih.gov/pubmed/22314896

I've the heard the pathway is gluconeogenesis[1] . From what I've read we need roughly 100g of carbs a day, and we can create all of it via gluconeogenesis.

Now, what i really wonder is; if we see diabetes from abusing the carbohydrate pathways, then what disease comes from abusing the ketone/gluconeogensis pathways ?

[1]: http://en.wikipedia.org/wiki/Gluconeogenesis

The article literally states:

the results highlight the critical role of beliefs about willpower in self-control performance

I don't know how generalizable the results are, and I'm not making claims about its generalizability. I'm simply refuting the notion that it's wholly incompatible with depletion theory. Speaking personally, I would have appreciated some notion of how common any belief whatsoever is for people.

Sometimes - but they ARE metabolized through the same pathway.

Essentially:

    Glucose ->[0] pyruvate ->[1] acetyl-coa -> TCA cycle

vs

    Fatty acids ->[2] acetyl-coa -> TCA cycle

The TCA is cycle is the actual main energy generating step.

Other times fat absolutely is converted to sugar. It all depends on the metabolic needs of the body and one building blocks are available, and what protein "workers" are able to use the ones that are available.

For example, fatty acid synthase converts acetyl coa back to a fatty acid [3].

[0] Glycolysis: http://en.wikipedia.org/wiki/Glycolysis

[1] pyruvate dehydrogenase: http://en.wikipedia.org/wiki/Pyruvate_dehydrogenase

[2] beta oxidation: http://en.wikipedia.org/wiki/Beta_oxidation

[3]: http://en.wikipedia.org/wiki/Fatty_acid_synthase

I toughed it out for six weeks and I was definitely in ketosis per ketostix testing. I felt as bad as I ever have. So it doesn't work for everyone.

Thanks for the info. I think I will have to do this over the holidays when I am not trying to crank through work deadlines.

People learn and create different ways to handle emotions. People experience differences and similarities in life experience. People resolve and analyze their histories, present and future evaluations differently, similarly, if at all. People have different temperaments, or similar. People can track their data independently to attempt to control their reactions internally to the external world, but life does things that make handling response not always controllable.

I can't say anything about your state anymore than I both simultaneously understand and do not understand my own.

IMO, the angry / irritated line is completly subjective. To the point where I would call them different intensity's of the same emotion.

Sadness can be a layer over anger - it's a more acceptable emotion to display or even experience.

Fruit has small amounts of fiber that slightly slow absorption. Honey does not. It has the exact same effect as any other sugar. Rather than "feeling" it, try measuring it.