Lisa Simpson said:
Atkins dieters are actually trying to get into this state of too much ketones. When I was preggers, it was a bad thing.
Ketosis happens because of too little glucose in the cells. It's all about the citric acid cycle. This is the main second-stage energy metabolism pathway, and it takes in both the products of glycolysis (which breaks down glucose, the end-stage of the digestion of carbohydrates) and the products of fatty acid oxidation (metabolism of fat).
To keep going, the citric acid cycle requires a supply of oxaloacetate, which can only come from glycolysis. Fatty acids don't produce it. So unless there is sufficient carbohydrate being broken down, the citric acid cycle grinds to an unceremonious halt and the products of fatty acid breakdown have nowhere to go. Except to become ketones.
The formation of ketones is a sort of sideways shunt to get rid of the products of fatty acid metabolism if they can't go the proper route, through the citric acid cycle. The point is that they still have quite a lot of energy left in them, they're really quite nutritious (ruminants actully utilise them a different way, via the ruminal micro-organisms). So if you're peeing out ketones rather than letting the fat be metabolised fully, obviously you're not getting the full energetic beneit of the catabolised fuel. It's a wasteful system, and it will promote weight loss just as a badly tuned engine will empty your petrol tank much sooner if it's only allowing you 20 miles to the gallon instead of 35.
And it makes you smell of ketones and it's a horribly unhealthy way to be and who cares if it works, anybody who does this on purpose is certifiably nuts.
This sort of ketosis (starvation, basically) is associated with low or maybe normal blood glucose. There's nothing stopping the glucose getting into the cells, the deficiency is in glucose (carbohydrate) intake. Diabetic ketoacidosis in contrast is associated with high blood glucose. The problem there is that the glucose can't get into the cells to get at the cytoplasm and the mitochondria where all this happens, because the insulin it needs to get past the cell membrane isn't there. It stays in the circulation and gets peed out unmetabolised. Same effect, but different way of getting there.
Of course you panic if a diabetic becomes ketotic, it means there's bugger-all glucose getting into the cells so things ain't good. But if your goal is to lose as much weight as possible, then I suppose ketosis becomes desirable as it shows that you've taken in so little glucose that even your fat metabolism has become inefficient.
They're all mad, I tell you.
Rolfe.
You know, these metabolic pathways, the workings of the body on the molecular level, and the real "energy" of life we can measure and quantify and manipulate, are just wonderfully fascinating. Why does anyone need woo-woo fantasies about mystical energies and vital forces when there's all this real, demonstrable, totally absorbing stuff to be amazed about?
