Hormonal reductionism is as myopic as biochemical reductionism

Biochemistry-based arguments can be very misleading. Yet, biochemistry can be extremely useful in the elucidation of diet and lifestyle effects that are suggested by well-designed studies of humans. If you start with a biochemistry-based argument though, and ignore actual studies of humans, you can easily convince someone that glycogen-depleting exercise (e.g., weight training) is unhealthy, because many health markers change for the worse after that type of exercise. But it is the damage caused by glycogen-depleting exercise that leads to health improvements, via short- and long-term compensatory adaptations ().

Biochemistry is very helpful in terms of providing “pieces for the puzzle”, but biochemical reductionism is a problem. Analogous to biochemical reductionism, and perhaps one example of it, is hormonal reductionism – trying to argue that all diet and lifestyle effects are mediated by a single hormone. A less extreme position, but still myopic, is to argue that all diet and lifestyle effects are mostly mediated by a single hormone.

One of my own “favorite” hormones is adiponectin, which I have been discussing for years in this blog (). Increased serum adiponectin has been found to be significantly associated with: decreased body fat (particularly decreased visceral fat), decreased risk of developing diabetes type 2, and decreased blood pressure. Adiponectin appears to also have anti-inflammatory and athero-protective properties.

As a side note, typically women have higher levels of serum adiponectin than men, particularly young women. Culturally we have a tendency to see young women as “delicate” and “vulnerable”. Guess what? Young women are the closest we get to “indestructible” in the human species. And there is an evolutionary reason for that, which is that fertile women have been in our evolutionary past, and still are, the bottleneck of any population. A population of 100 individuals, where 99 are men and 1 is a woman, will quickly disappear. If it is 99 women and 1 fertile man, the population will grow; but there will also be some problems due to inbreeding. Even if the guy is ugly the population will grow; without competition, he will look very cute.

Jung and colleagues measured various hormone levels in 78 obese people who had visited obesity clinics at five university hospitals (Ajou, Ulsan, Catholic, Hanyang and Yonsei) in Korea (). Those folks restricted their caloric intake to 500 calories less than their usual intake, and exercised, for 12 weeks. Below are the measured changes in tumor necrosis factor α (TNF-α, now called only TNF), interleukin-6 (IL-6), resistin, leptin, adiponectin, and interleukin-10 (IL-10).

We see from the table above that the hormonal changes were all significant (all at the P equal to or lower than 0.001 level except one, at the P lower than 0.05 level), and all indicative of health improvements. The serum concentrations of all hormones decreased, with two exceptions – adiponectin and interleukin-10, which increased. Interleukin-10 is an anti-inflammatory hormone produced by white blood cells. The most significant increase of the two was by far in adiponectin (P = .001, versus P = .041 for interleukin-10).

Now, should we try to find a way of producing synthetic adiponectin then? My guess is that doing that will not lead to very positive results in human trials; because, as you can see from the table, hormones vary in concert. At the moment, the only way to “supplement” adiponectin is to lose body fat, and that leads to concurrent changes in many other hormones (e.g., TNF decreases).

Trying to manipulate one single hormone, or build an entire health-improvement approach based on its effects, is myopic. But that is what often happens. Leptin is a relatively recent example.

One reason why biochemistry is so complex, with so many convoluted processes, is that evolution is a tinkerer that is “blind” to complexity. Traits appear at random in populations and spread if they increase reproductive success; even if they decrease survival success, by the way ().

Evolution is not an engineer, and is not even our “friend” (). To optimize our health, we need to “hack” evolution.

What is a good low carbohydrate diet? It is a low calorie one

My interview with Jimmy Moore should be up on the day that this post becomes available. (I usually write my posts on weekends and schedule them for release at the beginning of the following weeks.) So the time is opportune for me to try to aswer this question: What is a good low carbohydrate diet?

For me, and many people I know, the answer is: a low calorie one. What this means, in simple terms, is that a good low carbohydrate diet is one with plenty of seafood and organ meats in it, and also plenty of veggies. These are low carbohydrate foods that are also naturally low in calories. Conversely, a low carbohydrate diet of mostly beef and eggs would be a high calorie one.

Seafood and organ meats provide essential fatty acids and are typically packed with nutrients. Because of that, they tend to be satiating. In fact, certain organ meats, such as beef liver, are so packed with nutrients that it is a good idea to limit their consumption. I suggest eating beef liver once or twice a week only. As for seafood, it seems like a good idea to me to get half of one’s protein from them.

Does this mean that the calories-in-calories-out idea is correct? No, and there is no need to resort to complicated and somewhat questionable feedback-loop arguments to prove that calories-in-calories-out is wrong. Just consider this hypothetical scenario; a thought experiment. Take two men, one 25 years of age and the other 65, both with the same weight. Put them on the same exact diet, on the same exact weight training regime, and keep everything else the same.

What will happen? Typically the 65-year-old will put on more body fat than the 25-year-old, and the latter will put on more lean body mass. This will happen in spite of the same exact calories-in-calories-out profile. Why? Because their hormonal mixes are different. The 65-year-old will typically have lower levels of circulating growth hormone and testosterone, both of which significantly affect body composition.

As you can see, it is not all about insulin, as has been argued many times before. In fact, average and/or fasting insulin may be the same for the 65- and 25-year-old men. And, still, the 65-year-old will have trouble keeping his body fat low and gaining muscle. There are other hormones involved, such as leptin and adiponectin, and probably several that we don’t know about yet.

A low carbohydrate diet appears to be ideal for many people, whether that is due to a particular health condition (e.g., diabetes) or simply due to a genetic makeup that favors this type of diet. By adopting a low carbohydrate diet with plenty of seafood, organ meats, and veggies, you will make it a low calorie diet. If that leads to a calorie deficit that is too large, you can always add a bit more of fat to it. For example, by cooking fish with butter and adding bacon to beef liver.

One scenario where I don’t see the above working well is if you are a competitive athlete who depletes a significant amount of muscle glycogen on a daily basis – e.g., 250 g or more. In this case, it will be very difficult to replenish glycogen only with protein, so the person will need more carbohydrates. He or she would need a protein intake in excess of 500 g per day for replenishing 250 g of glycogen only with protein.

Lipotoxicity or tired pancreas? Abnormal fat metabolism as a possible precondition for type 2 diabetes

The term “diabetes” is used to describe a wide range of diseases of glucose metabolism; diseases with a wide range of causes. The diseases include type 1 and type 2 diabetes, type 2 ketosis-prone diabetes (which I know exists thanks to Michael Barker’s blog), gestational diabetes, various MODY types, and various pancreatic disorders. The possible causes include genetic defects (or adaptations to very different past environments), autoimmune responses, exposure to environmental toxins, as well as viral and bacterial infections; in addition to obesity, and various other apparently unrelated factors, such as excessive growth hormone production.

Type 2 diabetes and the “tired pancreas” theory

Type 2 diabetes is the one most commonly associated with the metabolic syndrome, which is characterized by middle-age central obesity, and the “diseases of civilization” brought up by Neolithic inventions. Evidence is mounting that a Neolithic diet and lifestyle play a key role in the development of the metabolic syndrome. In terms of diet, major suspects are engineered foods rich in refined carbohydrates and refined sugars. In this context, one widely touted idea is that the constant insulin spikes caused by consumption of those foods lead the pancreas (figure below from Wikipedia) to get “tired” over time, losing its ability to produce insulin. The onset of insulin resistance mediates this effect.

Empirical evidence against the “tired pancreas” theory

This “tired pancreas” theory, which refers primarily to the insulin-secreting beta-cells in the pancreas, conflicts with a lot of empirical evidence. It is inconsistent with the existence of isolated semi/full hunter-gatherer groups (e.g., the Kitavans) that consume large amounts of natural (i.e., unrefined) foods rich in easily digestible carbohydrates from tubers and fruits, which cause insulin spikes. These groups are nevertheless generally free from type 2 diabetes. The “tired pancreas” theory conflicts with the existence of isolated groups in China and Japan (e.g., the Okinawans) whose diets also include a large proportion of natural foods rich in easily digestible carbohydrates, which cause insulin spikes. Yet these groups are generally free from type 2 diabetes.

Humboldt (1995), in his personal narrative of his journey to the “equinoctial regions of the new continent”, states on page 121 about the natives as a group that: "… between twenty and fifty years old, age is not indicate by wrinkling skin, white hair or body decrepitude [among natives]. When you enter a hut is hard to differentiate a father from son …" A large proportion of these natives’ diets included plenty of natural foods rich in easily digestible carbohydrates from tubers and fruits, which cause insulin spikes. Still, there was no sign of any condition that would suggest a prevalence of type 2 diabetes among them.

At this point it is important to note that the insulin spikes caused by natural carbohydrate-rich foods are much less pronounced than the ones caused by refined carbohydrate-rich foods. The reason is that there is a huge gap between the glycemic loads of natural and refined carbohydrate-rich foods, even though the glycemic indices may be quite similar in some cases. Natural carbohydrate-rich foods are not made mostly of carbohydrates. Even an Irish (or white) potato is 75 percent water.

More insulin may lead to abnormal fat metabolism in sedentary people

The more pronounced spikes may lead to abnormal fat metabolism because more body fat is force-stored than it would have been with the less pronounced spikes, and stored body fat is not released just as promptly as it should be to fuel muscle contractions and other metabolic processes. Typically this effect is a minor one on a daily basis, but adds up over time, leading to fairly unnatural patterns of fat metabolism in the long run. This is particularly true for those who lead sedentary lifestyles. As for obesity, nobody gets obese in one day. So the key problem with the more pronounced spikes may not be that the pancreas is getting “tired”, but that body fat metabolism is not normal, which in turn leads to abnormally high or low levels of important body fat-derived hormones (e.g., high levels of leptin and low levels of adiponectin).

One common characteristic of the groups mentioned above is absence of obesity, even though food is abundant and often physical activity is moderate to low. Repeat for emphasis: “… even though food is abundant and often physical activity is moderate to low”. Note that having low levels of activity is not the same as spending the whole day sitting down in a comfortable chair working on a computer. Obviously caloric intake and level of activity among these groups were/are not at the levels that would lead to obesity. How could that be possible? See this post for a possible explanation.

Excessive body fat gain, lipotoxicity, and type 2 diabetes

There are a few theories that implicate the interaction of abnormal fat metabolism with other factors (e.g., genetic factors) in the development of type 2 diabetes. Empirical evidence suggests that this is a reasonable direction of causality. One of these theories is the theory of lipotoxicity.

Several articles have discussed the theory of lipotoxicity. The article by Unger & Zhou (2001) is a widely cited one. The theory seems to be widely based on the comparative study of various genotypes found in rats. Nevertheless, there is mounting evidence suggesting that the underlying mechanisms may be similar in humans. In a nutshell, this theory proposes the following steps in the development of type 2 diabetes:

    (1) Abnormal fat mass gain leads to an abnormal increase in fat-derived hormones, of which leptin is singled out by the theory. Some people seem to be more susceptible than others in this respect, with lower triggering thresholds of fat mass gain. (What leads to exaggerated fat mass gains? The theory does not go into much detail here, but empirical evidence from other studies suggests that major culprits are refined grains and seeds, as well as refined sugars; other major culprits seem to be trans fats, and vegetable oils rich in linoleic acid.)

    (2) Resistance to fat-derived hormones sets in. Again, leptin resistance is singled out as the key here. (This is a bit simplistic. Other fat-derived hormones, like adiponectin, seem to clearly interact with leptin.) Since leptin regulates fatty acid metabolism, the theory argues, leptin resistance is hypothesized to impair fatty acid metabolism.

    (3) Impaired fat metabolism causes fatty acids to “spill over” to tissues other than fat cells, and also causes an abnormal increase in a substance called ceramide in those tissues. These include tissues in the pancreas that house beta-cells, which secrete insulin. In short, body fat should be stored in fat cells (adipocytes), not outside them.

    (4) Initially fatty acid “spill over” to beta-cells enlarges them and makes them become overactive, leading to excessive insulin production in response to carbohydrate-rich foods, and also to insulin resistance. This is the pre-diabetic phase where hypoglycemic episodes happen a few hours following the consumption of carbohydrate-rich foods. Once this stage is reached, several natural carbohydrate-rich foods also become a problem (e.g., potatoes and bananas), in addition to refined carbohydrate-rich foods.

    (5) Abnormal levels of ceramide induce beta-cell apoptosis in the pancreas. This is essentially “death by suicide” of beta cells in the pancreas. What follows is full-blown type 2 diabetes. Insulin production is impaired, leading to very elevated blood glucose levels following the consumption of carbohydrate-rich foods, even if they are unprocessed.

It is widely known that type 2 diabetics have impaired glucose metabolism. What is not so widely known is that usually they also have impaired fatty acid metabolism. For example, consumption of the same fatty meal is likely to lead to significantly more elevated triglyceride levels in type 2 diabetics than non-diabetics, after several hours. This is consistent with the notion that leptin resistance precedes type 2 diabetes, and inconsistent with the “tired pancreas” theory.

Weak and strong points of the theory of lipotoxicity

A weakness of the theory of lipotoxicity is its strong lipophobic tone; at least in the articles that I have read. See, for example, this article by Roger H. Unger in the Journal of the American Medical Association. There is ample evidence that eating a lot of the ultra-demonized saturated fat, per se, is not what makes people obese or type 2 diabetic. Yet overconsumption of trans fats and vegetable oils rich in linoleic acid does seem to be linked with obesity and type 2 diabetes. (So does the consumption of refined grains and seeds, and refined sugars.) The theory of lipotoxicity does not seem to make these distinctions.

In defense of the theory of lipotoxicity, it does not argue that there cannot be thin diabetics. Many type 1 diabetics are thin. Type 2 diabetics can also be thin, even though that is much less common. In certain individuals, the threshold of body fat gain that will precipitate lipotoxicity may be quite low. In others, the same amount of body fat gain (or more) may in fact increase their insulin sensitivity under certain circumstances – e.g., when growth hormone levels are abnormally low.

Autoimmune disorders, perhaps induced by environmental toxins, or toxins found in certain refined foods, may cause the immune system to attack the beta-cells in the pancreas. This may lead to type 1 diabetes if all beta cells are destroyed, or something that can easily be diagnosed as type 2 (or type 1.5) diabetes if only a portion of the cells are destroyed, in a way that does not involve lipotoxicity.

Nor does the theory of lipotoxicity predict that all those who become obese will develop type 2 diabetes. It only suggests that the probability will go up, particularly if other factors are present (e.g., genetic propensity). There are many people who are obese during most of their adult lives and never develop type 2 diabetes. On the other hand, some groups, like Hispanics, tend to develop type 2 diabetes more easily (often even before they reach the obese level). One only has to visit the South Texas region near the Rio Grande border to see this first hand.

What the theory proposes is a new way of understanding the development of type 2 diabetes; a way that seems to make more sense than the “tired pancreas” theory. The theory of lipitoxicity may not be entirely correct. For example, there may be other mechanisms associated with abnormal fat metabolism and consumption of Neolithic foods that cause beta-cell “suicide”, and that have nothing to do with lipotoxicity as proposed by the theory. (At least one fat-derived hormone, tumor necrosis factor-alpha, is associated with abnormal cell apoptosis when abnormally elevated. Levels of this hormone go up immediately after a meal rich in refined carbohydrates.) But the link that it proposes between obesity and type 2 diabetes seems to be right on target.

Implications and thoughts

Some implications and thoughts based on the discussion above are the following. Some are extrapolations based on the discussion in this post combined with those in other posts. At the time of this writing, there were 90 posts on this blog, in addition to many comments. See under "Labels" at the bottom-right area of this blog for a summary of topics addressed. It is hard to ignore things that were brought to light in previous posts.

    - Let us start with a big one: Avoiding natural carbohydrate-rich foods in the absence of compromised glucose metabolism is unnecessary. Those foods do not “tire” the pancreas significantly more than protein-rich foods do. While carbohydrates are not essential macronutrients, protein is. In the absence of carbohydrates, protein will be used by the body to produce glucose to supply the needs of the brain and red blood cells. Protein elicits an insulin response that is comparable to that of natural carbohydrate-rich foods on a gram-adjusted basis (but significantly lower than that of refined carbohydrate-rich foods, like doughnuts and bagels). Usually protein does not lead to a measurable glucose response because glucagon is secreted together with insulin in response to ingestion of protein, preventing hypoglycemia.

    - Abnormal fat gain should be used as a general measure of one’s likelihood of being “headed south” in terms of health. The “fitness” level for men and women shown on the table in this post seem like good targets for body fat percentage. The problem here, of course, is that this is not as easy as it sounds. Attempts at getting lean can lead to poor nutrition and/or starvation. These may make matters worse in some cases, leading to hormonal imbalances and uncontrollable hunger, which will eventually lead to obesity. Poor nutrition may also depress the immune system, making one susceptible to a viral or bacterial  infection that may end up leading to beta-cell destruction and diabetes. A better approach is to place emphasis on eating a variety of natural foods, which are nutritious and satiating, and avoiding refined ones, which are often addictive “empty calories”. Generally fat loss should be slow to be healthy and sustainable.

    - Finally, if glucose metabolism is compromised, one should avoid any foods in quantities that cause an abnormally elevated glucose or insulin response. All one needs is an inexpensive glucose meter to find out what those foods are. The following are indications of abnormally elevated glucose and insulin responses, respectively: an abnormally high glucose level 1 hour after a meal (postprandial hyperglycemia); and an abnormally low glucose level 2 to 4 hours after a meal (reactive hypoglycemia). What is abnormally high or low? Take a look at the peaks and troughs shown on the graph in this post; they should give you an idea. Some insulin resistant people using glucose meters will probably realize that they can still eat several natural carbohydrate-rich foods, but in small quantities, because those foods usually have a low glycemic load (even if their glycemic index is high).

Lucy was a vegetarian and Sapiens an omnivore. We apparently have not evolved to be pure carnivores, even though we can be if the circumstances require. But we absolutely have not evolved to eat many of the refined and industrialized foods available today, not even the ones marketed as “healthy”. Those foods do not make our pancreas “tired”. Among other things, they “mess up” fat metabolism, which may lead to type 2 diabetes through a complex process involving hormones secreted by body fat.

References

Humboldt, A.V. (1995). Personal narrative of a journey to the equinoctial regions of the new continent. New York, NY: Penguin Books.

Unger, R.H., & Zhou, Y.-T. (2001). Lipotoxicity of beta-cells in obesity and in other causes of fatty acid spillover. Diabetes, 50(1), S118-S121.

Subcutaneous versus visceral fat: How to tell the difference?

The photos below, from Wikipedia, show two patterns of abdominal fat deposition. The one on the left is predominantly of subcutaneous abdominal fat deposition. The one on the right is an example of visceral abdominal fat deposition, around internal organs, together with a significant amount of subcutaneous fat deposition as well.

Body fat is not an inert mass used only to store energy. Body fat can be seen as a “distributed organ”, as it secretes a number of hormones into the bloodstream. For example, it secretes leptin, which regulates hunger. It secretes adiponectin, which has many health-promoting properties. It also secretes tumor necrosis factor-alpha (more recently referred to as simply “tumor necrosis factor” in the medical literature), which promotes inflammation. Inflammation is necessary to repair damaged tissue and deal with pathogens, but too much of it does more harm than good.

How does one differentiate subcutaneous from visceral abdominal fat?

Subcutaneous abdominal fat shifts position more easily as one’s body moves. When one is standing, subcutaneous fat often tends to fold around the navel, creating a “mouth” shape. Subcutaneous fat is easier to hold in one’s hand, as shown on the left photo above. Because subcutaneous fat tends to “shift” more easily as one changes the position of the body, if you measure your waist circumference lying down and standing up, and the difference is large (a one-inch difference can be considered large), you probably have a significant amount of subcutaneous fat.

Waist circumference is a variable that reflects individual changes in body fat percentage fairly well. This is especially true as one becomes lean (e.g., around 14-17 percent or less of body fat for men, and 21-24 for women), because as that happens abdominal fat contributes to an increasingly higher proportion of total body fat. For people who are lean, a 1-inch reduction in waist circumference will frequently translate into a 2-3 percent reduction in body fat percentage. Having said that, waist circumference comparisons between individuals are often misleading. Waist-to-fat ratios tend to vary a lot among different individuals (like almost any trait). This means that someone with a 34-inch waist (measured at the navel) may have a lower body fat percentage than someone with a 33-inch waist.

Subcutaneous abdominal fat is hard to mobilize; that is, it is hard to burn through diet and exercise. This is why it is often called the “stubborn” abdominal fat. One reason for the difficulty in mobilizing subcutaneous abdominal fat is that the network of blood vessels is not as dense in the area where this type of fat occurs, as it is with visceral fat. Another reason, which is related to degree of vascularization, is that subcutaneous fat is farther away from the portal vein than visceral fat. As such, it has to travel a longer distance to reach the main “highway” that will take it to other tissues (e.g., muscle) for use as energy.

In terms of health, excess subcutaneous fat is not nearly as detrimental as excess visceral fat. Excess visceral fat typically happens together with excess subcutaneous fat; but not necessarily the other way around. For instance, sumo wrestlers frequently have excess subcutaneous fat, but little or no visceral fat. The more health-detrimental effect of excess visceral fat is probably related to its proximity to the portal vein, which amplifies the negative health effects of excessive pro-inflammatory hormone secretion. Those hormones reach a major transport “highway” rather quickly.

Even though excess subcutaneous body fat is more benign than excess visceral fat, excess body fat of any kind is unlikely to be health-promoting. From an evolutionary perspective, excess body fat impaired agile movement and decreased circulating adiponectin levels; the latter leading to a host of negative health effects. In modern humans, negative health effects may be much less pronounced with subcutaneous than visceral fat, but they will still occur.

Based on studies of isolated hunger-gatherers, it is reasonable to estimate “natural” body fat levels among our Stone Age ancestors, and thus optimal body fat levels in modern humans, to be around 6-13 percent in men and 14–20 percent in women.

If you think that being overweight probably protected some of our Stone Age ancestors during times of famine, here is one interesting factoid to consider. It will take over a month for a man weighing 150 lbs and with 10 percent body fat to die from starvation, and death will not be typically caused by too little body fat being left for use as a source of energy. In starvation, normally death will be caused by heart failure, as the body slowly breaks down muscle tissue (including heart muscle) to maintain blood glucose levels.

References:

Arner, P. (2005). Site differences in human subcutaneous adipose tissue metabolism in obesity. Aesthetic Plastic Surgery, 8(1), 13-17.

Brooks, G.A., Fahey, T.D., & Baldwin, K.M. (2005). Exercise physiology: Human bioenergetics and its applications. Boston, MA: McGraw-Hill.

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

Taubes, G. (2007). Good calories, bad calories: Challenging the conventional wisdom on diet, weight control, and disease. New York, NY: Alfred A. Knopf.

Cheese consumption, visceral fat, and adiponectin levels

Several bacteria feed on lactose, the sugar found in milk, producing cheese for us as a byproduct of their feeding. This is why traditionally made cheese can be eaten by those who are lactose intolerant. Cheese consumption predates written history. This of course does not refer to processed cheese, frequently sold under the name “American cheese”. Technically speaking, processed cheese is not “real” cheese.

One reasonably reliable way of differentiating between traditional and processed cheese varieties is to look for holes. Cheese-making bacteria produce a gas, carbon dioxide, which leaves holes in cheese. There are exceptions though, and sometimes the holes are very small, giving the impression of no holes. Another good way is to look at the label and the price; usually processed cheese is labeled as such, and is cheaper than traditionally made cheese.

Cheese does not normally spoil; it ages. When vacuum-wrapped, cheese is essentially in “suspended animation”. After opening it, it is a good idea to store it in such a way as to allow it to “breathe”, or continue aging. Wax paper does a fine job at that. This property, extended aging, has made cheese a very useful source of nutrition for travelers in ancient times. It was reportedly consumed in large quantities by Roman soldiers.

Walther and colleagues (2008) provide a good review of the role of cheese in nutrition and health. The full reference is at the end of this post. They point out empirical evidence that cheese, particularly that produced with Lactobacillus helveticus (e.g., Gouda and Swiss cheese), contributes to lowering blood pressure, stimulates growth and development of lean body tissues (e.g., muscle), and has anti-carcinogenic properties.

The health-promoting effects of cheese were also reviewed by Higurashi and colleagues (2007), who hypothesized that those effects may be in part due to the intermediate positive effects of cheese on adiponectin and visceral body fat levels. They conducted a study with rats that supports those hypotheses.

In the study, they fed two groups of rats an isocaloric diet with 20 percent of fat, 20 percent of protein, and 60 percent of carbohydrate (in the form of sucrose). In one group, the treatment group, Gouda cheese (produced with Lactobacillus helveticus) was the main source of protein. In the other group, the control group, isolated casein was the main source of protein. The researchers were careful to avoid confounding variables; e.g., they adjusted the vitamin and mineral intake in the groups so as to match them.

The table below (click to enlarge) shows initial and final body weight, liver weight, and abdominal fat for both groups of rats. As you can see, the rats more than quadrupled in weight by the end of the 8-weight experiment! Abdominal fat was lower in the cheese group; one type of visceral fat, mesenteric, was significantly lower. Whole body weight-adjusted liver weight was higher in the cheese group. Liver weight increase is often associated with increased muscle mass. The rats in the cheese group were a little heavier on average, even though they had less abdominal fat.

The figure below shows adiponectin levels at the 4-week and 8-week marks. While adiponectin levels decreased in both groups, which was to be expected given the massive gain in weight (and probably body fat mass), only in the casein group the decrease in adiponectin was significant. In fact, the relatively small decrease in the cheese group is a bit surprising given the increase in weight observed.

If we could extrapolate these findings to humans, and this is a big “if”, one could argue that cheese has some significant health-promoting effects. There is one small problem with this study though. To ensure that the rats consumed the same number of calories, the rats in the casein group were fed slightly more sucrose. The difference was very small though; arguably not enough to explain the final outcomes.

This study is interesting because the main protein in cheese is actually casein, and also because casein powders are often favored by those wanting to put on muscle as part of a weight training program. This study suggests that the cheese-ripening process induced by Lactobacillus helveticus may yield compounds that are particularly health-promoting in three main ways – maintaining adiponectin levels; possibly increasing muscle mass; and reducing visceral fat gain, even in the presence of significant weight gain. In humans, reduced circulating adiponectin and increased visceral fat are strongly associated with the metabolic syndrome.

One caveat: if you think that eating cheese may help wipe out that stubborn abdominal fat, think again. This is a topic for another post. But, briefly, this study suggests that cheese consumption may help reduce visceral fat. Visceral fat, however, is generally fairly easy to mobilize (i.e., burn); much easier than the stubborn subcutaneous body fat that accumulates in the lower abdomen of middle-aged men and women. In middle-aged women, stubborn subcutaneous fat also accumulates in the hips and thighs.

Could eating Gouda cheese, together with other interventions (e.g., exercise), become a new weapon against the metabolic syndrome?

References:

Higurashi, S., Kunieda, Y., Matsuyama, H., & Kawakami, H. (2007). Effect of cheese consumption on the accumulation of abdominal adipose and decrease in serum adiponectin levels in rats fed a calorie dense diet. International Dairy Journal, 17(10), 1224–1231.

Walther, B., Schmid, A., Sieber, R., & Wehrmüller, K. (2008). Cheese in nutrition and health. Dairy Science Technology, 88(4), 389-405.

Adiponectin supplementation: Body fat loss

Adiponectin is a hormone exclusively secreted by body fat. This hormone has been recently gaining attention from researchers because of some of its functions. Two important ones are the regulation of glucose and fat metabolism.

Elevated levels of adiponectin are associated with increased insulin sensitivity, and increased fat catabolism (i.e., fat burning). And these associations appear to be causal. That is, adiponectin levels do not seem to be only markers, but causes of increased insulin sensitivity and fat catabolism.

In other words, an increase in circulating adiponectin seems to lead to increased insulin sensitivity and increased fat catabolism. Insulin sensitivity is the opposite of insulin resistance. The latter is a precursor to diabetes type 2, and is associated with elevated fasting and postprandial (i.e., after a meal) glucose levels.

Adiponectin also seems to work closely with leptin, another hormone implicated in a number of diseases of civilization. It appears that adiponecting and leptin modulate each other’s secretion and effects in metabolic processes.

So what do we do to increase our levels of circulating adiponectin?

Well, apparently there is only one guaranteed way, and that is to lose body fat!

Adiponectin is unique among hormones secreted by body fat in that it increases as body fat decreases. Other important body fat hormones, such as leptin, decrease with body fat loss.

The figure below (from: Poppitt et al., 2008) shows a graph where adiponectin levels are plotted against body mass index (BMI). BMI is strongly correlated with body fat percentage.

As you can see from the figure above adiponectin levels more than double when BMI goes from 26 to 20. One does not need to be obese to take advantage of this effect, and to benefit from having increased adiponectin levels.

The linear (Pearson) correlation between BMI and adiponectin levels is indicated as a high 0.551. The fluctuations around the line (the "line" looks more like a quasi-linear curve obtained through quadratic regression), which are why the correlation is not 1, are probably due chiefly to two factors:

    - BMI is not a very precise measure of body fat. A very muscular person will have a high BMI and low body fat. That person will consequently have much higher adiponectin levels than an obese person with equal BMI.

    - Adiponectin levels are naturally higher in women than in men. This is another point in favor of adiponectin, as women have always been the evolutionary bottleneck among our Paleolithic ancestors.

Now you know why doctors prescribe weight loss to patients with diabetes type 2.

And, when we look at various hunter-gatherer groups that were apparently free of diseases of civilization prior to westernization, there are only a few common denominators. Diet was not one of them, as Weston Price and others have shown us, at least not in the sense of what they included in their diet.

One of the few common denominators was arguably the fact that those hunter-gatherers typically had relatively low levels of body fat; an almost universal feature among non-westernized hunter-gatherers.

Reference:

Poppitt, S.D. et al. (2008). Postprandial response of adiponectin, interleukin-6, tumor necrosis factor-α, and C-reactive protein to a high-fat dietary load. Nutrition, 24(4), 322-329.

Adiponectin and tumor necrosis factor-alpha levels after a high saturated fat meal

This is one of those interesting studies where the authors start with some pre-conceived assumptions and end up concluding something else, some way toward the opposite of what they assumed.

My final interpretation of the study results is a bit different though. It suggests that the results are actually the opposite of what the authors originally assumed.

The authors of the study (Poppitt et al., 2008; full reference at the end of this post) start by stating that since “… dietary fat is associated with increased lipid storage, weight gain, and obesity …” it is important to study the effect of dietary fat intake on the blood levels of certain substances that are associated with lipid disorders, weight gain and obesity.

In short, the authors start from the assumption that dietary fat is bad. By the way, this type of indictment of all fats is not very common these days. Usually saturated fat is the target.

Since dietary fat is assumed to be bad for us, that justifies the authors’ goal of studying the effect of dietary fat on certain hormones associated with bad health, including the body fat-secreted hormones adiponectin and tumor necrosis factor-alpha. Low levels of serum adiponectin, and elevated levels of tumor necrosis factor-alpha, are associated with various health complications.

In the study, a high-fat test meal with approximately 59 g of fat (71% of energy as fat) was given at breakfast on two occasions to 18 healthy and lean men. These men had, on average, 23 years of age, a 31-inch waist, and a body mass index of 22.9. In other words, they were young and fit.

Two fatty meal variations were used, one with a lot more saturated fat than the other. Their ratio of saturated:unsaturated fatty acids was 71:29 for the high saturated fat meal, and 55:45 for the other. The table below provides a more detailed picture of the fat composition of the meals. The authors refer to these meals as instances of “acute intake of dietary lipid”.

Lunch, snack and dinner meals were also served to the participants. Those meals were nearly fat-free, with 1 to 3 g of fat only; apparently to help the participants “recover” from the high fat meal. They included plenty of refined grains (e.g., pasta) and fruit juices. Way to go; give these folks refined carbohydrates and sugars galore to help them recover from the “damage” done by the high fat meal!

Blood samples were collected at 0 (baseline), 1, 3, and 6 h for the measurement of various substances, including the body fat hormones adiponectin and tumor necrosis factor-alpha levels.

The figure below shows the variation in adiponectin levels at several times after the meal. The black circles are for the high saturated fat group, and the white circles for the other group. Adiponectin levels do not really start at the same level for both groups, which makes the graph a bit unclear; to better interpret the graph it may be a good idea to simply ignore the first (white) circle at the zero mark on the vertical axis. Also, no hormone levels were negative, of course; the zero on the vertical axis represents a reference value.

As we can see from the figure above, adiponectin levels go up for both groups after the fatty meal, and end up higher than they started for both groups; more for the high saturated fat than for the low saturated fat group. They are at very similar levels at the 24 h mark, but the levels at 24 h for the high saturated fat group appear to be a lot higher than they were right after the fatty meal. (The start point for the high saturated fat group being the first black circle from the left on the graph.) None of the differences are reported as significant. This is not surprising, given the small sample.

The figure below shows the variation in tumor necrosis factor-alpha levels at several times after the meal. This is an even more interesting one, because it suggests a possible negative effect of the low fat meals.

In terms of tumor necrosis factor-alpha levels, the figure above suggests that both groups end up higher than they started, by about the same amount, which is not very good. (With tumor necrosis factor-alpha, unlike adiponectin, the less you have the better - so to speak, the hormone has important functions.) Again, none of the differences, with the exception of one, are reported as significant. The exception is the tumor necrosis factor-alpha level at 6 h for the low saturated fat group, which is significantly lower. But that difference disappears at the 10 h mark, never to be seen again.

Interestingly, note that tumor necrosis factor-alpha levels go up very clearly after the additional meals, which were low fat meals rich in refined carbohydrate and sugars. The variation in adiponectin is not as clearly associated with the additional meals. The points at which those meals were served are indicated by the arrows at the top of the graph; first arrow from left for lunch, second for a snack, and third arrow for dinner.

The conclusion by the authors of the study was that there is “… no evidence from this study of lean, healthy male subjects that the adipose hormone adiponectin is sensitive to acute intake of dietary lipid or to an increase in fatty acid saturation.” They do acknowledge the reduction in tumor necrosis factor-alpha up until the start of the low fat meals, and say that the “mechanism leading to the decrease in TNF-alpha on the high SFA:USFA treatment in our trial is unknown to us.”

My interpretation of this study is that, at least for young and lean men:

- There is some evidence that dietary saturated fat intake leads to increased levels of circulating adiponectin and decreased levels of tumor necrosis factor-alpha in the first few hours after a meal rich in saturated fat; with plenty of palmitic acid in it, by the way, of which animal fat is a great source. These are desirable and health-promoting hormonal responses.

- These is some evidence that meals high in refined carbohydrates and sugars increase levels of circulating tumor necrosis factor-alpha in the hours following the meals. Elevated levels of tumor necrosis factor-alpha are not good news; something that I guess is implied by the name of the hormone.

- There is some evidence that dietary saturated fat intake leads to an increase in adiponectin levels 24 h after a high fat meal, even when it is followed by low fat meals high in refined carbohydrates and sugars. This suggests a protective effect, which is in line with the hypothesis that adiponectin is not only a health marker by also a health-promoting hormone.

Due to the small sample used, none of the conclusions above is based on statistically significant results. More research is needed in the future, with larger samples. I am not sure it will happen though. This study’s findings were obviously accidental, and saturated fat phobia is still widespread.

Adiponectin is highly correlated with body weight, particularly weight associated with body fat mass. So, if you were able to achieve weight loss through a low carbohydrate diet involving a high consumption of saturated fat, there is absolutely no need to change that based on the results of this study.

Plus, saturated fat has the added benefit that it increases HDL cholesterol, the “good” cholesterol.

Reference:

Poppitt, S.D. et al. (2008). Postprandial response of adiponectin, interleukin-6, tumor necrosis factor-α, and C-reactive protein to a high-fat dietary load. Nutrition, 24(4), 322-329.

Adiponectin, inflammation, diabetes, and heart disease

Humans, like many animals, evolved to be episodic eaters and spend most of their time fasting. Body fat is the main store of energy in the human body. Excess dietary carbohydrates and fat are stored as body fat, in specialized cells known as adipocytes. Excess dietary protein is not normally stored as body fat.

Adipocytes can be seen as being part of a very important and distributed endocrine organ, being responsible for the release of many different hormones into the bloodstream. One of these hormones is adiponectin. Other important hormones secreted by body fat tissue are leptin and tumor necrosis factor-alpha.

Among hormones, adiponectin is particularly interesting because it is negatively correlated with body fat mass. That is, unlike other hormones such as leptin and tumor necrosis factor-alpha, a decrease in body fat mass (a well known health marker) is associated with an increase in adiponectin. This has led some researchers to speculate that adiponectin is a causative factor that promotes health, in addition to being a health marker.

Jung and colleagues (2008; full reference at the end of this post) studied 78 obese individuals (41 females) who participated in an exercise program during 12 weeks. The exercise program involved mostly low intensity aerobic activities, such as brisk walking. The individuals also took an appetite suppressant, with the goal of reducing their calorie intake by about 500 kcal per day.

The table below (click on it to enlarge) shows various measurements for the participants before and after the 12-week intervention.

From the table above we can say that there were significant reductions in weight, body mass index (BMI), waist and hip circumference, waist-to-hip ratio (WHR), total body fat, and total fasting cholesterol and triglycerides. However, the participants were still obese at the end of the intervention, with an average body fat percentage of 35.5.

The table below shows the concentrations of various hormones secreted by body fat tissue, as well as other types of tissue, before and after the 12-week intervention. These hormones are all believed to be health indicators and/or health causes.

We see from the table above that the hormonal changes were all significant (all at the P < .001 level except one, at the P < .05 level), and all indicative of health improvements. The serum concentrations of all hormones decreased, with two exceptions – adiponectin and interleukin-10, which increased. Interleukin-10 is an anti-inflammatory hormone produced by white blood cells. The most significant increase of the two was by far in adiponectin (P = .001, versus P = .041 for interleukin-10).

One of the most promising effects of adiponectin seems to be an increase in insulin sensitivity. This effect appears to be unrelated to any effects on insulin secretion. That is, adiponectin seems to act directly on various cells, including muscle cells, increasing their ability to clear glucose from the blood. This effect seems to be one of the underlying, and previously unknown, reasons why loss of body fat improves health in those who suffer from diabetes type 2.

Increased serum adiponectin has been found to be significantly associated with: decreased body fat and particularly visceral fat, decreased risk of developing diabetes type 2, decreased blood pressure, and decreased fasting triglycerides.

Adiponectin appears to also have anti-inflammatory and athero-protective properties.

On average, women have higher levels of serum adiponectin than men.

According to Giannessi and colleagues (2007) administration of adiponectin in mice has shown positive results. Since research on adiponectin is new, it will probably be some time until related drugs are developed. Giannessi and colleagues also note that fish oil and vanadium salts may increase the synthesis and release of adiponectin.

So far it seems that the most effective way of increasing adiponectin levels is weight loss, particularly through body fat loss. Even as new drugs are developed, this will likely remain the most natural and safe way of increasing adiponectin levels.

All of this helps in the identification of missing links between body fat loss and health improvement. It seems that losing body fat has an effect similar to that of supplementation; it increases the blood concentration of a health-promoting substance - adiponectin!

References:

Giannessi, D., Maltinti, M., & Del Ry, S. (2007). Adiponectin circulating levels: A new emerging biomarker of cardiovascular risk. Pharmacological Research, 56(6), 459-467.

Gil-Campos, M., Cañete, R., & Gil, A. (2004). Adiponectin, the missing link in insulin resistance and obesity. Clinical Nutrition, 23(5), 963-974.

Jung, S.H. et al. (2008). Effect of weight loss on some serum cytokines in human obesity: increase in IL-10 after weight loss. The Journal of Nutritional Biochemistry, 19(6), 371-375.

Body fat and disease: How much body fat can I lose in one day?

Body fat is not an inert deposit of energy. It can be seen as a distributed endocrine organ. Body fat cells, or adipocytes, secrete a number of different hormones into the bloodstream. Major hormones secreted by adipose tissue are adiponectin and leptin.

Estrogen is also secreted by body fat, which is one of the reasons why obesity is associated with infertility. (Yes, abnormally high levels of estrogen can reduce fertility in both men and women.) Moreover, body fat secretes tumor necrosis factor-alpha, a hormone that is associated with generalized inflammation and a number of diseases, including cancer, when in excess.

The reduction in circulating tumor necrosis factor-alpha and other pro-inflammatory hormones as one loses weight is one reason why non-obese people usually experience fewer illness symptoms than those who are obese in any given year, other things being equal. For example, the non-obese will have fewer illness episodes that require full rest during the flu season. In those who are obese, the inflammatory response accompanying an illness (which is necessary for recovery) will often be exaggerated.

The exaggerated inflammatory response to illness often seen in the obese is one indication that obesity in an unnatural state for humans. It is reasonable to assume that it was non-adaptive for our Paleolithic ancestors to be unable to perform daily activities because of an illness. The adaptive response would be physical discomfort, but not to the extent that one would require full rest for a few days to fully recover.

Inflammation markers such as C-reactive protein are positively correlated with body fat. As body fat increases, so does inflammation throughout the body. Lipid metabolism is negatively affected by excessive body fat, and so is glucose metabolism. Obesity is associated with leptin and insulin resistance, which are precursors of diabetes type 2.

Some body fat is necessary for survival; that is normally called essential body fat. The table below (from Wikipedia) shows various levels of body fat, including essential levels. Also shown are body fat levels found in athletes, as well as fit, “not so fit” (indicated as "Acceptable"), and obese individuals. Women normally have higher healthy levels of body fat than men.

If one is obese, losing body fat becomes a very high priority for health reasons.

There are many ways in which body fat can be measured.

When one loses body fat through fasting, the number of adipocytes is not actually reduced. It is the amount of fat stored in adipocytes that is reduced.

How much body fat can a person lose in one day?

Let us consider a man, John, whose weight is 170 lbs (77 kg), and whose body fat percentage is 30 percent. John carries around 51 lbs (23 kg) of body fat. Standing up is, for John, a form of resistance exercise. So is climbing stairs.

During a 24-hour fast, John’s basal metabolic rate is estimated at about 2,550 kcal/day. This is the number of calories John would spend doing nothing the whole day. It can vary a lot for different individuals; here it is calculated as 15 times John’s weight in lbs.

The 2,550 kcal/day is likely an overestimation for John, because the body adjusts its metabolic rate downwards during a fast, leading to fewer calories being burned.

Typically women have lower basal metabolic rates than men of equal weight.

For the sake of discussion, we expect each gram of John’s body fat to contribute about 8 kcals of energy, assuming a rate of conversion of body fat to calories of about 90 percent.

Thus during a 24-hour fast John burns about 318 g of fat, or about 0.7 lbs. In reality, the actual amount may be lower (e.g., 0.35 lbs), because of the body's own down-regulation of its basal metabolic rate during a fast. This down-regulation varies widely across different individuals, and is generally small.

Many people think that this is not much for the effort. The reality is that body fat loss is a long term game, and cannot be achieved through fasting alone; this is a discussion for another post.

It is worth noting that intermittent fasting (e.g., one 24-hour fast per week) has many other health benefits, even if no overall calorie restriction occurs. That is, intermittent fasting is associated with health benefits even if one fasts every other day, and eats twice one's normal intake on the non-fasting days.

Some of the calories being burned during John's 24-hour fast will be from glucose, mostly from John’s glycogen reserves in the liver if he is at rest. Muscle glycogen stores, which store more glucose substrate (i.e., material for production of glucose) than liver glycogen, are mobilized primarily through anaerobic exercise.

Very few muscle-derived calories end up being used through the protein and glycogen breakdown pathways in a 24-hour fast. John’s liver glycogen reserves, plus the body’s own self-regulation, will largely spare muscle tissue.

The idea that one has to eat every few hours to avoid losing muscle tissue is complete nonsense. Muscle buildup and loss happen all the time through amino acid turnover.

Net muscle gain occurs when the balance is tipped in favor of buildup, to which resistance exercise and the right hormonal balance (including elevated levels of insulin) contribute.

One of the best ways to lose muscle tissue is lack of use. If John's arm were immobilized in a cast, he would lose muscle tissue in that arm even if he ate every 30 minutes.

Longer fasts (e.g., lasting multiple days, with only water being consumed) will invariably lead to some (possibly significant) muscle breakdown, as muscle is the main store of glucose-generating substrate in the human body.

In a 24-hour fast (a relatively short fast), the body will adjust its metabolism so that most of its energy needs are met by fat and related byproducts. This includes ketones, which are produced by the liver based on dietary and body fat.

How come some people can easily lose 2 or 3 pounds of weight in one day?

Well, it is not body fat that is being lost, or muscle. It is water, which may account for as much as 75 percent of one’s body weight.

References:

Elliott, W.H., & Elliott, D.C. (2009). Biochemistry and molecular biology. New York: NY: Oxford University Press.

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

Large, V., Peroni, O., Letexier, D., Ray, H., & Beylot, M. (2004). Metabolism of lipids in human white adipocyte. Diabetes & Metabolism, 30(4), 294-309.