You wants studies -- do a search.
The next source of fuel would be....? Muscle.
Just because you have an "empty stomach" doesn't mean you're gylcogen depleted.
For everyone who says they had success with this method, I can find someone who had equal success without it -- which is another way of saying there were other factors involved and not those percieved.
Swimming is only a good way to burn calories if you aren't a good swimmer. Skilled, leisurly swimming will barely burn the calories of a bowl of oatmeal in 30 minutes.
The next source of fuel would be....? Muscle.
Just because you have an "empty stomach" doesn't mean you're gylcogen depleted.
For everyone who says they had success with this method, I can find someone who had equal success without it -- which is another way of saying there were other factors involved and not those percieved.
Swimming is only a good way to burn calories if you aren't a good swimmer. Skilled, leisurly swimming will barely burn the calories of a bowl of oatmeal in 30 minutes.