Thursday, December 24, 2009

Growth hormone: The fountain of youth

Growth hormone, also known as human growth hormone, seems to be implicated in a number of metabolic conditions associated with aging, and, more generally, poor health.

In adults, growth hormone deficiency is associated with: decreased calcium retention and osteoporosis, loss of muscle mass, increased fat deposition, decreased protein synthesis, and immunodeficiency. In children, growth hormone deficiency is associated with stunted growth.

Levels of growth hormones decline with age, and their decrease is believed to contribute to the aging process. Abdominal obesity is associated with low levels of growth hormone, and is also associated with the onset of the metabolic syndrome, a precursor of diabetes and cardiovascular disease.

While there are many treatments in the market that include exogenous administration of growth hormones (e.g., through injection), there are several natural ways in which growth hormone levels can be increased. These natural ways can often lead to more effective and sustainable results than prescription drugs.

For example, fasting stimulates the natural production of growth hormone. So does vigorous exercise, particularly resistance exercise with a strong anaerobic component (not cardio though). And, to the surprise of many people, deep sleep stimulates the natural production of growth hormone, perhaps more than anything else. (Although only once every 24 hours; sleeping all day does not seem to work.)

In fact, during a 24-hour period, growth hormone typically varies in pulses, or cycles. The pulses are somewhat uniformly distributed during the day, with a peak occurring at night. The graph below (source: Fleck & Kraemer, 2004) plots the typical variation of growth hormone during a 12-hour period, including the deep sleep period.

As you can see, growth hormone peaks during deep sleep; which is achieved a few hours after one goes to bed, and not too long before one wakes up.

By the way, if you want to know more about human physiology and metabolism, forget about popular diet and exercise books. Next to peer-reviewed academic articles (which are often hard to read), the best sources are college textbooks used in courses on physical education, nutrition, endocrinology, and related topics. The book from which the graph above was taken (Fleck & Kraemer, 2004), is a superb example of that.


Fleck, S.J., & Kraemer, W.J. (2004). Designing resistance training programs. Champaign, IL: Human Kinetics.

Wednesday, December 23, 2009

Half-hearted Atkins diet and cardiovascular disease

I would like to comment on a recent article comparing the Atkins, Ornish and South Beach diets (Miller et al., 2009; full reference at the end of this posting), which has been causing quite a lot of commotion among bloggers recently. Especially low carb. bloggers.

An excellent post by Michael Eades clarifies a number of issues with the study, including what one could argue is the study's main flaw. Apparently the study compared a half-hearted Atkins diet, with probably equally half-hearted Ornish and South Beach diets.

I refer to the study's Atkins diet as half-hearted because it seems to rely on a daily consumption of between 120 and 180 grams of carbohydrates. This is unlikely to lead to ketosis, the cornerstone of the Atkins diet, where the body uses ketone bodies (made from dietary as well as body fat) as a source of energy.

As I see it, the main findings of the study were that the participants in the half-hearted Atkins diet, after a period of 4 weeks on the diet, and when compared with the participants in the other diets, had: (a) greater levels of total cholesterol and LDL cholesterol, with only a small improvement in their HDL cholesterol and triglycerides levels; and (b) greater levels of markers for inflammation (e.g., C-reactive protein).

The participants were young and healthy. Their average age was 30.6 years, and their average body mass index was 22.6. On average, their total cholesterol was 184.9 mg/dL, triglycerides were 78.1 mg/dL, LDL cholesterol was 107.2 mg/dL, and HDL cholesterol was 62.2 mg/dL. These are arguably fairly healthy numbers; although quite a few doctors might want to put most of these folks preventively on statins because of their LDL being greater than 100.

What I find interesting about this study, and consistent with both my own experience and also a theory that I have, is that it suggests that a low carb. diet has to really be low carb. in order to bring about the benefits that one normally sees as a result of a diet that induces ketosis. A diet with, say, > 150 g of refined grains per day, is not really a low carb. diet.

Again, in my experience, and that of many other people, a truly low carb. diet (very low in, if not devoid of, refined carbs and sugars), will lead to an impressive increase in HDL cholesterol (especially for those who have low HDL to start with), an equally impressive decrease in triglycerides, increased insulin sensitivity, and possibly a decrease in LDL.

However, a half-hearted Atkins diet may actually lead to elevated LDL (of the small-dense type), and more inflammation, just like this study suggests it does, without the benefits regarding HDL and trigs. The reason is that the still relatively high level of carbohydrate intake, especially if it comes in the form of refined carbs. and sugars, will lead to higher levels of insulin being secreted into the bloodstream. This will promote increased body fat deposition. The extra saturated fat being consumed will be turned into body fat, and not used as energy, starving the cells and leading to increased hunger.

A diet rich in saturated fat may indeed be bad when it is also a diet even moderately rich in insulin-boosting, easily digestible carbs. This may be one of the main reasons why there have been so many studies in the past showing a correlation between saturated fat consumption and heart disease; studies that typically did not control for carbohydrate consumption.

In a recent interview on the Livin' La Vida Low-Carb Blog, Dr. John Salerno goes into more detail regarding this issue, recommending a much more rigid adoption of the Atkins diet than many think is okay. (In fact, I often talk to people who think that if they cut a very high carb. intake in half - e.g., from 400 to 200 grams per day - replacing the carbs with fat, they will be halfway into a full blown Atkins diet.) Dr. Salerno has worked in the past with Dr. Atkins. He calls his diet the Silver Cloud Diet. I am not sure I agree with all that Dr. Salerno had to say, but his argument in favor of a diet very low in carbs. does make sense to me.

Finally, I think that it is dangerous to extrapolate the results of any study, no matter how comprehensive, to the population in general. Each individual is unique in terms of his or her genetic makeup and life history; the latter also influences metabolic patterns. (Even identical twins raised together may display different metabolic patterns, because of their different life histories.)  So, while a low carb. diet may work well for a lot of people, it may have very negative effects on a few. Increases in inflammation markers and adverse effects on LDL cholesterol (especially when LDL is measured directly, accounting for particle numbers and sizes) are warning signs that any low carb. dieter should pay attention to.


Miller, M. et al. (2009). Comparative effects of three popular diets on lipids, endothelial function, and c-reactive protein during weight maintenance. Journal of the American Dietetic Association, 109, 713-717.

Saturday, December 19, 2009

Total cholesterol and cardiovascular disease: A U-curve relationship

The hypothesis that blood cholesterol levels are positively correlated with heart disease (the lipid hypothesis) dates back to Rudolph Virchow in the mid-1800s.

One famous study that supported this hypothesis was Ancel Keys's Seven Countries Study, conducted between the 1950s and 1970s. This study eventually served as the foundation on which much of the advice that we receive today from doctors is based, even though several other studies have been published since that provide little support for the lipid hypothesis.

The graph below (source:, with many thanks to O Primitivo) shows the results of one study, involving many more countries than Key's Seven Countries Study, that actually suggests a NEGATIVE linear correlation between total cholesterol and cardiovascular disease.

Now, most relationships in nature are nonlinear, with quite a few following a pattern that looks like a U-curve (plain or inverted); sometimes called a J-curve pattern. The graph below (source also: shows the U-curve relationship between total cholesterol and mortality, with cardiovascular disease mortality indicated through a dotted red line at the bottom.

This graph has been obtained through a nonlinear analysis, and I think it provides a better picture of the relationship between total cholesterol (TC) and mortality. Based on this graph, the best range of TC that one can be at is somewhere between 210, where cardiovascular disease mortality is minimized; and 220, where total mortality is minimized.

The total mortality curve is the one indicated through the full blue line at the top. In fact, it suggests that mortality increases sharply as TC decreases below 200.

Now, these graphs relate TC with disease and mortality, and say nothing about LDL cholesterol (LDL). In my own experience, and that of many people I know, a TC of about 200 will typically be associated with a slightly elevated LDL (e.g., 110 to 150), even if one has a high HDL cholesterol (i.e., greater than 60).

Yet, most people who have a LDL greater than 100 will be told by their doctors, usually with the best of the intentions, to take statins, so that they can "keep their LDL under control". (LDL levels are usually calculated, not measured directly, which itself creates a whole new set of problems.)

Alas, reducing LDL to 100 or less will typically reduce TC below 200. If we go by the graphs above, especially the one showing the U-curves, these folks' risk for cardiovascular disease and mortality will go up - exactly the opposite effect that they and their doctors expected. And that will cost them financially as well, as statin drugs are expensive, in part to pay for all those TV ads.

Tuesday, December 8, 2009

Refined carbs, sugar, and cholesterol: My own experience

A few years ago I went to the doctor for a routine appointment, and I was told that my LDL cholesterol was elevated. I was in my early 40s. My lipid profile was the following - LDL: 156, HDL: 38, triglycerides: 188. The LDL was calculated. I was weighing about 210 lbs, which was too high for my height (5 ft 8 in). My blood pressure was low, as it has always been - systolic: 109, diastolic: 68.

My doctor gave me the standard advice in these cases: exercise, lose weight, and, most importantly, reduce your intake of saturated fat. I was also told that I would probably have to take statins, as my high LDL likely had something to do with my genetic makeup. Again, this is quite standard, and we see it all over the place, particularly in commercials for statins.

I told my doctor that I would do some research on the topic, which I am going to save for other posts. Let me get to the point, by telling you what my lipid profile is today - LDL: 123, HDL: 66, triglycerides: 46. Again, the LDL value is calculated. I am weighing about 152 lbs now, with about 13 percent of body fat.

The HDL and triglycerides numbers above are shown in bold font because my research convinced me that these two numbers are the ones most people should really worry about when trying to address what is known as dyslipidemia. Here I am assuming that only standard lipid profiles are available; there are better alternatives, such as particle type analyses, which are not yet standard.

Many people who suffer from cardiovascular disease have low LDL cholesterol, but very few of those have high HDL cholesterol, which is one of the best predictors of cardiovascular disease among lipids. More specifically, if you have an HDL higher than 60, you have a very small chance of developing cardiovascular disease. (It can happen, but it is very unlikely, with a percentage chance in the single digits.)

Interestingly, low HDL cholesterol is also associated with the metabolic syndrome. This syndrome is characterized by the following:

- High fasting serum glucose (hyperglycemia), which is one of many signs of insulin resistance, a precursor to diabetes type 2;
- High blood pressure;
- Abdominal obesity (also known as pot or beer belly);
- Low HDL cholesterol; and
- Elevated triglycerides.

Now, you may ask, how did you increase your HDL? Well, I tried a number of things - diet and lifestyle changes - and had a blood test every 3 months. After a while I was able to put all of the measures in a spreadsheet table, and correlate them using a statistical software that I developed, to give me an idea of what was going on.

Weight was a big factor on LDL, and I was able to bring my weight down to 150 lbs and my LDL to below 100 at some point. For me, and many other people, body weight and LDL cholesterol are strongly and positively correlated (the higher the weight, the higher the LDL cholesterol - actually body fat seems to be the real culprit). Moreover, my LDL seemed to decrease more markedly when my weight was on the way down, and not as much when it was stable, even if low.

But the HDL would only increase if I increased my saturated fat intake. The problem is that every time I increased my saturated fat intake my LDL would go up; it reached 162 at one point, when my HDL went up to a modest but encouraging 47. That was my highest HDL until I eliminated refined carbs and sugars (e.g., bread, pasta, cereals, doughnuts, bagels, regular sodas) from my diet.

When I brought my intake of refined carbs and sugars down to zero, my intake of protein and saturated fat went up. Either that would happen, or I would starve, because you have to eat something. (I figured that I would not die by doing a low carb/high fat-protein experiment for 3 months to see what happened.) Also, I dramatically increased my dietary cholesterol - two to four eggs per day, organ meats, and seafood.

That is when my HDL shot up, to 66, and my LDL went down. Yes, my LDL levels seem to be negatively correlated with dietary saturated fat and cholesterol amounts, as long as I do not consume refined carbs and sugars. Moreover, it is very likely that my LDL particle size increased, and large LDL particles DO NOT cause atherosclerosis because they cannot penetrate the artery walls.

So, the bottom line is that, at least for me, an INCREASE in saturated fat and a DECREASE in refined carbs and sugars, happening together, seem to have taken me out of my previous path toward the metabolic syndrome.

Moreover, I feel a lot more energetic than before, my immune system seems to have gotten better at fighting disease, and even my pollen allergies are not as bad as they were before. Admittedly, these benefits may be strongly associated with the weight loss and the related reduction in body fat percentage.

I hope this post is helpful to others. The standard advice that people with high LDL cholesterol receive, which usually focuses on reducing saturated fat intake, has a big problem. When you reduce your intake of a type of food, you usually increase your intake of other types of food. Most people who try to reduce their saturated fat intake invariably increase their carb intake, usually with the wrong types of carb-rich foods (the man-made ones), simply because they go hungry.