Does not eating affect concentration/test performance?

[freshbagels]

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Not true. Some people are prone to hypoglycemia, endocrine disorder or not.

I am not against fasting at all. I go several hours (even days) without eating or consuming carbohydrates for that matter.

No, hypoglycemia is a pathophysiological state. Extended (i.e. 24 hr+) fasting slightly decreases one's blood glucose levels (i.e. from ~5 to ~4.6 mM), but not to the level of a hypoglycemic T1DM patient (<3.5 mM), and certainly not enough to cause cognitive dysfunction. See here for a recent paper and here for an older review.

Think about this evolutionarily:

Our genome was probably selected during the Late-Paleolithic era (50,000–10,000 BC), during a time humans existed as hunter-gatherers (6). At that time there were no guarantees in finding food, resulting in intermixed periods of feast and famine. In addition, physical activity had to be a part of our ancestors’ daily living as forage and the hunt for food must have been done through physical activity (15). Cycling between feast and famine, and thus oscillations in energy stores, as well as between exercise and rest, was characteristic in the Late-Paleolithic era and might have driven the selection of genes involved in the regulation of metabolism (30).

It does not make intuitive sense to have a normally-functioning body enter phsyical and cognitive shutdown because one hasn't eaten in 24 hours. We regulate our blood sugar extremely well under a variety of allostatic conditions, and any disturbance from our homeostatic norm (hypo- or hyper-glycemia) has catastrophic consequences, as you well know.

 

[HughMyron]

Get on IIFYM brah. U mirin'?

 

[deleted303591]

No, hypoglycemia is a pathophysiological state. Extended (i.e. 24 hr+) fasting slightly decreases one's blood glucose levels (i.e. from ~5 to ~4.6 mM), but not to the level of a hypoglycemic T1DM patient (<3.5 mM), and certainly not enough to cause cognitive dysfunction. See here for a recent paper and here for an older review.

Think about this evolutionarily:



It does not make intuitive sense to have a normally-functioning body enter phsyical and cognitive shutdown because one hasn't eaten in 24 hours. We regulate our blood sugar extremely well under a variety of allostatic conditions, and any disturbance from our homeostatic norm (hypo- or hyper-glycemia) has catastrophic consequences, as you well know.

You think you know what you are talking about, but you really have no idea what you are talking about. I am aware of all of this.

What about a growing individual going through a growth spurt, who does not consume enough carbohydrates and calories to compensate?

What about somebody who does endurance sports, who does not consume enough carbohydrates and calories for recovery?

And yes, there are people who have hypoglycemia (or have a tendency to develop it), without some sort of serious (or even diagnosable) endocrine disorder. I would know. You wouldn't. You can cite all kinds of c***, but you don't have any sort of perspective on this issue.

 

[deleted303591]

Most foods have some carbs in them. How much are you eating? <10g per day? Less?

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Sometimes I go days without eating at all.

< 40 grams a day is feasible and does not take a lot of effort. I would not bother trying to go < 20, if one eats like 2500 kcal/day.

I have severe gastroparesis, due to a rare autoimmune disease that I have-Autoimmune Autonomic Neuropathy, basicaly (actually it is Ganglionopathy, more specifically).

FYI, diabetes is the most common cause of gastroparesis. I just happen to have type 1 (autoimmune) diabetes with a rare autoimmune disease effecting my autonomic nervous system.

 

[jenniferleigh]

I have real problems keeping my weight up and yes it has very much affected my ability to study in the past. Now that I have myself on a rigid eating plan my grades have gone up 15-20 points on tests.

 

[freshbagels]

You think you know what you are talking about, but you really have no idea what you are talking about. I am aware of all of this.

What about a growing individual going through a growth spurt, who does not consume enough carbohydrates and calories to compensate?

What about somebody who does endurance sports, who does not consume enough carbohydrates and calories for recovery?

And yes, there are people who have hypoglycemia (or have a tendency to develop it), without some sort of serious (or even diagnosable) endocrine disorder. I would know. You wouldn't. You can cite all kinds of c***, but you don't have any sort of perspective on this issue.

Calm down. Let me quote myself again:

One does not simply stumble into true hypoglycemia unless one has an endocrine disorder (like T1/T2DM). One's fasting blood glucose stays relatively constant for at least 24 hr, although that number can be shortened if one exercises or otherwise depletes their body's stores.

Pathological (i.e. cognitive-impairing hypoglycemia) is not something an endocrinologically competent person falls into without consciously, as you (and I!) said, depleting their glycogen stores. Even then, one can (after a period of adaptation) perform totally normally running on ketones (to head this off at the pass: ketosis that a dieter experiences is a different condition than DKA that you are familiar with). We know this because we have an ideal fasting model (Ramadan) to check relative blood sugar levels, cognitive ability, physical performance, and true hypoglycemia in normal individuals does not occur.

Can you cite any sort of case report of recurrent hypoglycemia in an individual without an endocrine disorder?

The whole point is that one will not fall into a hypoglycemic state from moderate fasting, unless one also goes out and runs repeat 10ks without refueling. For a student or someone interested in either muscle hypertrophy or fat loss? Not going to happen.

 

[Sephiroth]

I actually tend to feel more awake and alert is I don't eat much during the day. Digestion is tiring. If not for the fact that I'm naturally pretty skinny and couldn't eat enough just later in the day to be able to gain weight, I probably do it most of the time.

 

[MedPR]

Sometimes I go days without eating at all.

< 40 grams a day is feasible and does not take a lot of effort. I would not bother trying to go < 20, if one eats like 2500 kcal/day.

I have severe gastroparesis, due to a rare autoimmune disease that I have-Autoimmune Autonomic Neuropathy, basicaly (actually it is Ganglionopathy, more specifically).

FYI, diabetes is the most common cause of gastroparesis. I just happen to have type 1 (autoimmune) diabetes with a rare autoimmune disease effecting my autonomic nervous system.

That sounds intense.. I hope the treatment isn't bad 🙁

I have real problems keeping my weight up and yes it has very much affected my ability to study in the past. Now that I have myself on a rigid eating plan my grades have gone up 15-20 points on tests.

Not trying to call you out, but the only people I've ever met who have had problems keeping weight up are people with eating disorders. I would legitimately be interested to hear the story of someone who could not gain, or even maintain, weight while on a caloric surplus.

 

[jenniferleigh]

You are right you don't lose weight if you are eating enough calories. I am not saying it was healthy. I am just saying that because I was doing that it did affect my performance in school when my weight was very low. I am more aware of the situation and actually plan my meals for the day. I have GI issues myself and need to eat every 2-3 hours so it makes it challenging. I am only sharing my experience and feel that if you aren't getting enough calories you may not be studying to your full potential.

 

[alexanne]

I researched this awhile ago so it's not fresh in my mind, however from what I remember - when ketosis is reached (after glycogen reserves have ran out – 48hrs approx.. in women), the body slows down the catabolism of amino acids from muscles/organs (the brain can use glutamine as fuel), and instead converts fatty acids into ketones. The brain is able to survive just fine on these ketones from what I've read. So physiologically, the brain gets the fuel it need... I'm not sure if this directly correlates with cognitive performance, though.

Hope to find a definitive answer on this.

 

[Hemorrage]

In my opinion, eating healthy food frequently is much more conducive to strong brain function. I avoid greasy and oily foods at all costs

 

[CrimsonKing]

In my opinion, eating healthy food frequently is much more conducive to strong brain function. I avoid greasy and oily foods at all costs

Avoiding grease full of saturated fats make sense. Avoiding oily foods which are often full of juicy (and essential) Omega-3's is a silly decision.