brain power

[vincentfromyay]

when we study at length do we use up more energy?

and if we do, it is significant enough to, say, lose weight?

[plasmodesmata11]

I believe you would only be connecting new synapses and paths for thinking, or storing away information in your memory. This does require energy, but such an insignificant amount to the energy muscles use that I doubt it is relevant. But i guess you do use more energy, sure. Just not a ton.

[vincentfromyay]

thanks plasmode. when we say we're exhausted after studying are we actually exhausted? or does our head simply hurt from all the mental activity? what is the difference between the way we feel after study and the way we feel after, say, a game of tennis or a work-out; in both instances we might say we're exhausted but what actually is the case?

[mith]

mental fatigue is probably not comparable to muscular fatigue

[koyal]

Hi,
I Think the main difference is that when we do intense brain activity, we use up blood glucose where as in long term physical activity, we burn up also fatty acids stored in the adipose cells. So, we can reduce weight by reducing body fat by physical exercise, but not by mental exercise.
Also, both use up oxygen from the blood, but whereas more oxygen is replenished by increased breath rate during physical exercise, it does not happen so during mental exercise and can easily make one feel tired due to the oxygen deplation in the blood.
Regards,
Koyal

[mith]

However, this means, if your brain were to use a larger portion of glucose, the rest of the body would receive less and fat would be burned to supplement the energy deficit. So wouldn't you be indirectly burning fats anyway?

[koyal]

Hi Mith,
True, but then I would think that the amount of fat burnt during exercise is much more than that during mental exercise.
Regards,
Koyal

[kolean]

As compared to basal metabolism?
(Just the usual housekeeping energy to keep the organism alive).

[mith]

@koyal, then the main difference isn't whether one type of exercise uses fat or not, you're talking about intensity of power output.

[koyal]

Hi mith,
Yes, in a way Yes and in away No. The main point I want to make is that the brain depends only on blood glucose for its energy requirements, where as other body cells can also burn fat and get energy. Since you get more energy by burning fat compared to glucose, and during intense mental activity, most of the other body organs are practically at rest, the amount of fat that need to be burnt by other body cells is very small.
This is not the case with long duration physical exercise where after initial using up of the blood glucose, the cells start using up the fat for energy.
Regards,
Koyal

[JackBean]

koyal:
1) brain can use also ketone bodies
2) body takes as much energy, as it needs, not that it burns 1 g of glucose or 1 g of fat...

[koyal]

Hi JackBean,
Yes, ketone bodies can be used by brain, but as I understand, it is a very slow process and is used only when blood glucose is in short supply for longer periods as in fasting. For faster energy requirements, the body first uses ATP and glucose derived from glycogen stored in the muscle tissues and turns to fat oxidation as a delayed source for energy.Here is a reference in this connection:
http://www.medbio.info/Horn/Time%206/mu ... bolism.htm
Also here is another reference explaining how carbohydrate foods are essential to enhance brain activity:

http://www.fi.edu/learn/brain/carbs.html#brainenergy

Please let me know your comments on these.

Regards,
Koyal