Bob Ross wrote:Please do, Cynthia.
Happy to, Bob.
Disclaimer: I am not a doctor or biochemist, nor do I play one on the Internet. But I've been looking at these things for over ten years now.
The South Beach approach is not what I would consider "low carb." I would call it a "moderate" or "modified" carb way of eating. It's been shown that very low carb ways of eating work in much the same way, but are nearly impossible for the average person to maintain long term. It seems to me that the South Beach Diet would be much more sustainable, theoretically prolonging the good effects. As we all know, once people go back to their former eating habits, they also go back to the problems that were caused by them.
The primary cardiovascular benefits of a modified carb approach are that it will go a long way toward normalizing blood levels of cholesterol and triglycerides, and help someone to drop excess weight if they have any to lose.
An *extremely* simplified explanation of how this works follows, with a particular emphasis on cholesterol levels for the sake of length.
First, let's note that somewhere around 80% of the cholesterol in the human body at any given time was manufactured by the body, not taken in through dietary sources. About 93% of the cholesterol in the body is located within cells, providing many wonderful benefits such as: absorption of fat-soluble vitamins; coating of nerve cells; working to maintain the structure of cells; regulating nutrient intake for the cells; and being intimately involved in the production of hormones such as testosterone, estrogen, and the adrenal hormones. It is essential.
Where we get into trouble is when too much cholesterol is floating around in the bloodstream. Cholesterol levels in the cells are naturally regulated, but bloodstream levels are not.
If cells do not have enough cholesterol within to perform their vital tasks, they either must signal the body to produce more or take it up from the bloodstream. So, obviously, if we can get the cells to slow their rate of production, they *must* make up the difference by harvesting cholesterol, particularly low-density lipoprotein (LDL - the "bad" cholesterol*), from the bloodstream.
This is precisely how the statins lower blood levels of cholesterol. They interfere with a critical step in the intracellular production of cholesterol, forcing cholesterol to be brought in from the bloodstream.
The main hormone that drives cholesterol manufacture in the body is insulin. (It is also the hormone that drives fat storage.) As with many mechanisms in the body, it has an opposite player, the hormone glucagon. Glucagon inhibits the production of cholesterol.
Therefore, in order to slow down cholesterol production without using statins, what we want to accomplish is to somehow keep insulin levels low and glucagon levels high.
Obviously we cannot eliminate insulin since we need it to live, as it plays several vital roles, the most familiar one being blood glucose regulation.
However, since insulin is released in response to an increase of glucose in the bloodstream, if we can limit the amount of carbohydrate available to be broken down into glucose, we can reduce and level off the amount of insulin available to drive cholesterol production in the cells.
That's basically how a reduced carb eating regimen works to reduce cholesterol levels.
Make sense?
The South Beach approach is not as radical as many others. However, a modified carb diet such as this still seeks to keep the level of insulin as low and steady as possible. This is accomplished by the amount and kind of carbohydrate ingested, as well as the amount and kind of fats taken in.
The emphasis is on complex carbohydrates (including goodly amounts of both soluble and insoluble fiber), protein, and beneficial fats so that the breakdown to glucose is much slower and less dramatic. This keeps insulin levels in check.
And as we have seen, if you keep insulin levels in check the body will harvest more cholesterol from the bloodstream, reducing those levels.
I'd be happy to talk about the other benefits and issues raised here if you have a particular question about them, but this is probably long enough already.
* I'm not going to get into the LDL vs HDL part of all this unless someone particularly wants to hear about it.