Posted: May 20, 2011 1:32 am
Apollonius wrote:
It's science. Insulin is a fat storage hormone. Lower insulin, store less fat. Low carb is sound.
but its not..... insulin and glucagon are hormones responsible for maintaining the levels of blood glucose. Insulins primary role is to make the liver/kidneys stop producing glucose, and for various organs to take up glucose whilst its plentiful.
blood glucose levels are supposed to be about 4mM, this is important because too much mucks up osmotic potential and can screw the kidneys up. it also can stick to things, resulting in glycosolated proteins, impaired function of blood vessels - in particular where there are lots of capillaries, hence issues with the retina, liver, kidneys spleen and the extremities.
when they're too low the brain suffers - the brain consumes ONLY glucose, and a lot of it, so shortages lead to hypoglycemia, comas and death (obviously the latter two are at the extreme end)
when you feed the levels of blood glucose go up as its absorbed by the gut, the liver and kidneys are still producing glucose, as the levels of glucose go up, as the concentration of insulin increases, the liver stops gluconeogenesis, and starts storing glucose as glycogen, as do other organs, this replenishes the livers store of glucose, and then fatty acid synthesis (its a catabolic process so the priority is on having energy stores before long term storage) as the sugar high wears off then the liver reverts to gluconeogenesis.
insulin might well stimulate FAS, but its main role is in maintaining homeostasis.
as for low carb, by switching to protein as the main part of the diet you are forcing the metabolic pathways to use fat, as it doesn't want to use protein for fuel. the problem is that without carb input you quickly end up with lots of ketone bodies and acidification of the blood (not good) (not to mention the demands put on the kidneys due to them having to get rid of a lot more nitrogen)
on the other hand whilst calories in ~ calories out might be simplistic, its is fundamentally sound (laws of thermodynamics) and whilst some people may have genetic or medical predispositions for weight gain, they cannot put it on if they dont eat it.