Wednesday, February 13, 2008

The Effects of a High-Fat Diet on Health and Weight: Does It Raise Cholesterol?

Who wants to be buried inside the great food pyramid? (Image by hair_k)

Continuing with the analysis of the blood results after my high-fat diet experiment, I'm going to examine my cholesterol values next. Before that, however, I'm going to pretend like I know what I'm talking about and mention some of the prevailing views (or conventional wisdom, as I like to call it) on the subject. And since this is a particularly tricky subject, it will probably take more than one post to cover entirely.

People who don't really know much about cholesterol have usually heard that it's generally bad for you; the lower your cholesterol levels, the healthier you are. The same people also usually assume that the cholesterol you eat is directly related to the cholesterol in your blood - i.e., the more cholesterol you eat, the higher your blood cholesterol levels will be.

Then there are people who know a little about cholesterol, maybe from newspapers or television or whatever. These people are quick to point out that it's not so much the cholesterol itself that is harmful, but LDL or low-density lipoprotein, often called the "bad cholesterol" (as opposed to HDL or high-density lipoprotein, the "good cholesterol"). They may even note that it's the relation of LDL to HDL that is important. These people say that eating foods rich in cholesterol will probably raise your blood cholesterol levels, but even more important is the amount of saturated fat you eat. So what you should do is keep your LDL levels low and your HDL levels high while keeping the total cholesterol level moderate. And how do you do that? Well you drink from the Holy Grail, of course: eat lots of bread, pasta and potatoes, lots of vegetables and fruit, a little lean meat, and limit your fat intake, especially saturated fat.

And then there are people like Uffe Ravnskov who say that the matter is hardly that simple. Why is HDL good and LDL bad? Ravnskov writes:

The reason is that a number of follow-up studies have shown that a lower-than-normal level of HDL-cholesterol and a higher than-normal level of LDL-cholesterol are associated with a greater risk of having a heart attack, and conversely, that a higher-than-normal level of HDL-cholesterol and a lower-than normal LDL-cholesterol are associated with a smaller risk. Or, said in another way, a low HDL/LDL ratio is a risk factor for coronary heart disease.

However, a risk factor is not necessarily the same as the cause. Something may provoke a heart attack and at the same time lower the HDL/LDL ratio. Many factors are known to influence this ratio.

If you're interested, I recommend you read the free excerpts from his book titled "The Cholesterol Myths". The difference between Ravnskov's writing and your average google search result is that he actually provides references to the scientific studies he's talking about. I can't tell you how much it frustrates me to read the words "scientific studies prove that [insert random claim here]" without any mention of the studies. Even worse is "it is widely known that [insert random claim]" without references.

So, which group of people are correct? Are they all wrong? Out of their minds? To find out, we'll have to look at what the studies say. And then, of course, we have the results from my own experiment, which I can always refer to when I want to say that something is "widely known" and "scientifically proven". I believe it was Einstein who said, "A sample size of one is more than adequate."

Go to next post on this experiment

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