nuttzilla said:
I hear ya man. The nutritional sciences, especially sports nutrition, have more general misconceptions than any other subjects in my experience. Part of the problem is all the straight bullshit you see on TV, and then some guy at your local gym spouting it off. I just got out of a nutritional biochemistry class so if you have any other specific questions throw them up on the supplementation and dieting forum and I'll be happy to answer them the best I can!
Yeah i've found so many cases of something being sad or misinterpreted and taken to be the god given truth. Some of the "diet" pill adds on tv and even some of the informercials actually make me question how they can legally make those claims. As much as i agree this topic if very diet realted i think conditioning may be better suited for the discussion.
Now still have some questions regarding your reply, and do to the nature of this thread it seems to serve as valid grounds for this topic of discussion. (been doing some reading)
Now the majority of the post i totally agree with (not necessarly agruing anything mind you), but in summary the basic principle that you have submitted is basically dealing with the body utilizing fat as its preffered method of fuel for lower intensity training. The higher the degree of intesity mesured in this case by the VO2 which can also be measured in BPM determines the amount glycogen supplies required for the activity. Now this aspect of fat utilization basically is relevent to all times of day mind you partiularly usefull in the morning.
Supporting my statement earlier, during the post-absorptive phase (in the morning once you wake up) glucagon secretion increases and insulin levels drop. Glucagon stimulates hormone sensitive lipase which mobilizes fatty acids from the stored triacylglycerol. Fatty acids become a very important fuel during this time. This, along with jogging at a low VO2 max level (around 50%), is an effective method to lose fat.
Now this portion howver is the nail on the head as far as the possibly benefits of running on an empty stomach.
Now as per my understanding of the affects of glucagon is that it is basically a counter measure to when the body has an insufficent amont of blood glucose levels, this results in glycogenolysis and lipolysis (or more glucose + fatty acids). This again under my understanding is the result of being hypoglycemic, which would not be the result of a post-absorptive phase as no additional energy has been added to the body upon waking as no meal has been taken in. The increased glucose derived from the liver also requires the utilization of insulin to promptly take advantage of this energy for the muscles and other glucose requiring activities such as the CNS.
Now many of the activities here are based on the availability of glucose or the amount of carbohydrate consumption that a person has undertaken prior to the activity. however the fat burning that is suggested being around 50% VO2 max is independent of glucose availability during any period of the day. Any activity that exceeds this level dramitically will require the further use of carbohydrates as fuel, this does burn more net calories however a lesser extent from bodyfat.
So then my question would be why is there a reason to not eat before activity in the morning? The amount of calories burned from fat is more dependent on the method or intensity of the activity in question, then by the availability of glucose. The lack of glucose also prevents the body from performing higher intensity training at this time, and thus forgoes the increased overall caloric expendature associated with this type of activity.
The lipolysis caused by glocagon i can see being the sole benefit of low intensity activity without any pre workout caloric consumption. Do you have any idea how significant this process is to the body?
I can see now through some reading that this process will not directly lead to catabolism, i would like to conclusivly see that there is in fact a material benefit from the pre breakfest run.
Hopefully i got things clear there and my assumptions were in order, the material i was going over got real confusing when i started covering hormones in addition to energy supplies.