Thursday, February 28, 2008

The Effects of a High-Fat Diet on Health and Weight - Blood Test Analysis Part 2/2

Glucose is also known as grape sugar. (Photo by AHMED)

Continuing with the results of my high-fat diet experiment, I'm going to analyse the rest of the numbers today. If you have no idea of what I'm talking about, you may wish to start reading from the beginning.

There are all kinds of strange names of tests done on my blood in the letter I got from the doctor, so I'm going to have to turn to good old Google for explanations. First in line appears to be blood glucose, which is used to measure the amount of a type of sugar (called glucose) in your blood. A high blood glucose is an indication of diabetes. Abnormally low blood glucose, or hypoglycemia, is uncommon in adults.

Since glucose comes from carbohydrates, it would seem logical that a diet high in fat and protein does not raise blood glucose levels. Normal levels depend, once again, on who you ask: according to the Diabetes Health Center, fasting levels below 5.5 mmol/l are normal, whereas the Finnish health care system defines levels between 4-6.1 mmol/l as normal. My blood glocuse is 5.0, which seems to be in the normal range. It's difficult to say whether my blood glucose level has increased, decreased or stayed the same, since this is the first time I've had it measured, but at least in my case eating lots of saturated fat and protein did not result in elevated blood glucose levels.

Next up is hemoglobin. The normal levels for men are between 13.5-16.5 g/dl in America and 13.4-16.7 in Finland. Lower levels are usually caused by iron deficiency and lead to symptoms of anemia, so a very low hemoglobin level is unhealthy. My hemoglobin is 17.0 g/dl. The last time it was measured it was slightly above normal, so it seems not to have been affected by the diet. Also, high hemoglobin runs in my family (even though we eat very differently), so I presume it has more to do with your genes than your diet.

All the other tests seem to measure the amount and size of red and white blood cells. All the levels are within normal range, so I'm going to make the assumption that eating a high-fat diet did not mess up my blood cells.

When reading these results, keep in mind that I excluded things like bread, pasta and potatoes from my diet, so these results don't say much about what would happen if you ate large amounts of both complex carbohydrates and (saturated) fats. That, however, is an experiment I'd rather not perform on myself...

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Thursday, February 21, 2008

The Effects of a High-Fat Diet on Health and Weight - Blood Test Analysis Part 1/2

Does eating this raise your cholesterol? It depends. (Photo by phil.lees)

It's been a while since I've had the chance to post, so here goes, finally. The last time I got so caught up in the mysterious world of cholesterol that I didn't even mention what my cholesterol levels were, even though I'd been waiting for the results for so long and so anxiously. Still, nevermind. Here they are:

LDL: 3 mmol/l
HDL: 2.24 mmol/l
Total: 5.7 mmol/l
Triglycerides: 0.92 mmol/l

The units are millimoles per liter, which apparently is the world standard unit for measuring cholesterol in blood. The US will have nothing to do with such standards, of course, so a conversion to mg/dl is in order:

LDL: 117 mg/dl
HDL: 87.36 mg/dl
Total: 222.3 mg/dl
Triglycerides: 81.88 mg/dl

According to the American Heart Association, the desirable level for total blood cholesterol is less than 200 mg/dl, which translates to 5.13 mmol/l. So, clearly my total cholesterol level is higher than what is said to be desirable.

The optimal level for LDL is less than 100 mg/dl (or 2.56 mmol/l), while the optimal level for HDL is more than 60 mg/dl (or 1.54 mmol/l). My levels exceed both.

Finally, the optimal level for triglycerides is less than 150 mg/dl (or 3.84 mmol/l). Mine are way below that.

So, my LDL and total cholesterol are higher than desirable, which may well have something to do with the fact that I've eaten ridiculous amounts of fat (both monounsaturated and saturated). Keep in mind, though, that when you're HDL levels are high, it raises your total cholesterol levels as well; thus, it is very possible to exceed the optimal total cholesterol level by having optimal levels of HDL. I haven't seen any upper limits for HDL before it becomes unhealthy.

Also, as I mentioned before, perhaps more interesting than HDL and LDL themselves is their relation: my LDL/HDL ratio is 1.33 and my total/HDL ratio is 2.54. Both of these numbers are associated with a low risk of cardiovascular disease.

As I've said, I don't necessarily hold these claims about optimal and unhealthy value ranges to be true, but hopefully this gives you some idea of how a high-fat diet relates to conventional wisdom on cholesterol.

Remember that the value ranges presented earlier are guidelines for Americans; the guidelines for Europeans are quite different. Every country has its own. For example, here's a comparison of the guidelines from US and Finland:


As you can see, the recommended levels for HDL and triglycerides show considerable variation.

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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."

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Monday, February 11, 2008

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

This is not how you attach a health file to an e-mail. (Photo by Supercapacity)

The unthinkable has happened: the results finally came this morning. I lost hope when I tried to call them last week and ask if they could send them to me by e-mail, and the nurse (who obviously had no clue how to attach a file to an e-mail) got very upset and actually hung up on me. That's customer service right there.

So, now I've got a page full of numbers to interpret. Let's start with blood pressure. According to conventional wisdom, ideal blood pressure values are less than 120/80 mmHg (120 systolic, 80 diastolic). A blood pressure of 140/90 mmHg is considered high blood pressure, while a blood pressure somewhere in between means prehypertension. Then again, in the UK the normal range is 110-140 mmHg for systolic pressure and 70-90 mmHg for diastolic pressure.

My blood pressure is 122/69 mmHg, which is a little difficult to interpret, since the systolic pressure is a little higher than the ideal value and the diastolic pressure is clearly in the ideal range. I don't have a reference value from earlier, so it's hard to say what kind of effect my high-fat diet has had, but I do remember that I've had very low blood pressure for as long as I can remember. Some doctors have even said it was too low. For example, before the diet, I often felt dizzy getting up from bed, which is a sign of low blood pressure.

So, in the light of the evidence, I would have to agree with the conventional wisdom that saturated fat increases blood pressure, at least in individuals (okay, one individual) with very low blood pressure. Whether it increases or lowers blood pressure in people with hypertension is hard to say. Then again, some of the recommended diets for lowering blood pressure, such as the DASH diet, have received criticism for advocating a high intake of carbohydrates.

If you look at the DASH diet plan, you'll see that it's the same diet being advocated by doctors and health professionals all over the western world: lots of grains and grain products (bread, cereals and pasta), low-fat or non-fat dairy foods and small amounts of lean meat and fish. This diet has been the Holy Grail of nutrition for the past few decades, but as you may have noticed by now, I'm very sceptical towards it. The reasons that we are told to eat lots of grains are economical, not biological - bread is full of energy and dirt cheap to produce. That doesn't mean it's healthy for you, however.

Whether my current blood pressure is better or worse than it was before is difficult to say. I haven't really read the studies done in this area, but if you're eating or planning on eating a diet high in saturated fat, be aware that it may raise your (systolic) blood pressure somewhat.

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Sunday, February 3, 2008

The Effects of a High-Fat Diet on Health and Weight : Saturated, Monounsaturated or Polyunsaturated?

Game meat is low in saturated fat. (Photo by Pperinik)

It's been over a week now and still no sign of the results from the blood test. Got to love the effectiveness of the public health service.

During excruciating hours of waiting, I've been reading more about saturated, monounsaturated and polyunsaturated fats. I was under the impression that the paleolithic diet consisted of quite a lot of saturated fat, but it seems that I was wrong - they did eat a considerable amount of animal fats, but since it was game meat, it contained little saturated fat. I knew that organs were prized over lean meat for their high energy content, but what was news to me was the fact that they too had a low saturated fat content.

This, of course, casts some doubt over my hypothesis. If the natural diet of the human race was low in saturated fat, doesn't it make sense that a diet high in saturated fat is unnatural and therefore harmful? Maybe. On the other hand, something that is unnatural is not necessarily harmful. Also, there have been studies on populations that eat a diet high in saturated fat and protein that have not been able to show any correlation between saturated fat intake and diseases such as atherosclerosis. And then there are studies that show how people with a high intake of polyunsaturated fats - the ones touted as being the greatest thing since sliced bread - end up having the very diseases they were trying to avoid.

In my mind, the question is much more complex than simply saying that eating butter will clog your arteries. For example, it could make a difference if you eat your saturated fat with complex carbohydrates instead of protein. I'm hoping the results from the blood test will provide at least some answers. If I ever get them.

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