Monday, July 29, 2013

Could grain-fed beef liver be particularly nutritious?


There is a pervasive belief today that grain-fed beef is unhealthy, a belief that I addressed before in this blog () and that I think is exaggerated. This general belief seems to also apply to a related meat, one that is widely acknowledged as a major micronutrient “powerhouse”, namely grain-fed beef liver.

Regarding grain-fed beef liver, the idea is that cattle that are grain-fed tend to develop a mild form of fatty liver disease. This I am inclined to agree with.

However, I am not convinced that this is such a bad thing for those who eat grain-fed beef liver.

In most animals, including Homo sapiens, fatty liver disease seems to be associated with extra load being put on the liver. Possible reasons for this are accelerated growth, abnormally high levels of body fat, and ingestion of toxins beyond a certain hormetic threshold (e.g., alcohol).

In these cases, what would one expect to see as a body response? The extra load is associated with high oxidative stress and rate of metabolic work. In response, the body should shuttle more antioxidants and metabolism catalysts to the organ being overloaded. Fat-soluble vitamins can act as antioxidants and catalysts in various metabolic processes, among other important functions. They require fat to be stored, and can then be released over time, which is a major advantage over water-soluble vitamins; fat-soluble vitamins are longer-acting.

So you would expect an overloaded liver to have more fat in it, and also a greater concentration of fat-soluble vitamins. This would include vitamin A, which would give the liver an unnatural color, toward the orange-yellow range of the spectrum.

Grain-fed beef liver, like the muscle meat of grain-fed cattle, tends to have more fat than that of grass-fed animals. One function of this extra fat could be to store fat-soluble vitamins. This extra fat appears to have a higher omega-6 fat content as well. Still, beef liver is a fairly lean meat; with about 5 g of fat per 100 g of weight, and only 20 mg or so of omega-6 fat. Clearly consumption of beef liver in moderation is unlikely to lead to a significant increase in omega-6 fat content in one’s diet (). By consumption in moderation I mean approximately once a week.

The photo below, from Wikipedia, is of a dish prepared with foie gras. That is essentially the liver of a duck or goose that has been fattened through force-feeding, until the animal develops fatty liver disease. This “diseased” liver is particularly rich in fat-soluble vitamins; e.g., it is the best known source of the all-important vitamin K2.



Could the same happen, although to a lesser extent, with grain-fed beef liver? I don’t think it is unreasonable to speculate that it could.

Sunday, July 28, 2013

Brown Fat: It's a Big Deal

Non-shivering thermogenesis is the process by which the body generates extra heat without shivering.  Shivering is a way for the body to use muscular contractions to generate heat, but non-shivering thermogenesis uses a completely different mechanism to accomplish the same goal: a specialized fat-burning tissue called brown fat.  Brown fat is brown rather than white because it's packed with mitochondria, the power plants of the cell.  Under cold conditions, these mitochondria are activated, using a specialized molecular mechanism called uncoupling* to generate heat.

The mechanism of brown fat activation has been worked out fairly well in rodents, which rely heavily on non-shivering thermogenesis due to their small body size.  Specialized areas of the hypothalamus in the brain sense body temperature (through sensors in the brain and body), body energy status (by measuring leptin and satiety signals), stress level, and probably other factors, and integrate this information to set brown fat activity.  The hypothalamus does this by acting through the sympathetic nervous system, which heavily innervates brown fat.  As an aside, this process works basically the same in humans, as far as we currently know.  Those who claim that rodent models are irrelevant to humans are completely full of hot air**, as the high degree of conservation of the hypothalamus over 75 million years of evolution demonstrates.

Two new studies concurrently published in the Journal of Clinical Investigation last week demonstrate what I've suspected for a long time: brown fat can be 'trained' by cold exposure to be more active, and its activation by cold can reduce body fatness.

Read more »

Saturday, July 27, 2013

Zucchini: The Home Gardener's Worst Friend? With bonus garden-related rambling.

One of my main gardening goals has been to harvest more of something than I can eat, despite my limited gardening space here in the Emerald City.  I want the feeling of abundance that comes with having to preserve and give away food because I can't eat it all.

Enter zucchini.  My grandfather used to say that in New Jersey in summertime, you'd have to keep your car doors locked, otherwise the car would be full of zucchini the next time you got in!  In mid-May, I planted two starts from my local grocery store labeled "green zucchini", with no further information.  I put them in a bed that used to be a pile of composted horse manure, and that I had also cover cropped, mulched, fertilized, and loosened deeply with my broadfork.  They look pleased.


Read more »

Tuesday, July 16, 2013

The Genetics of Obesity, Part III

Genetics Loads the Gun, Environment Pulls the Trigger

Thanks to a WHS reader* for reminding me of the above quote by Dr. Francis Collins, director of the US National Institutes of Health**.  This is a concept that helps reconcile the following two seemingly contradictory observations:
  1. Roughly 70 percent of obesity risk is genetically inherited, leaving only 30 percent of risk to environmental factors such as diet and lifestyle.
  2. Diet and lifestyle have a large impact on obesity risk.  The prevalence of obesity has tripled in the last 30 years, and the prevalence of extreme obesity has increased by almost 10-fold.  This is presumably not enough time for genetic changes to account for it.
Read more »

Monday, July 15, 2013

Return to the Source Parkour Camp

For those who are interested in natural movement training, this summer my friend Rafe Kelley will be hosting an interesting three-day event near Bellingham, WA called "Return to the Source".  Rafe is skilled in a variety of movement disciplines and is the co-founder of the Seattle parkour gym Parkour Visions.  Parkour is a very fun sport that hones our natural ability to skillfully navigate physical obstacles, but it's usually done in an urban context.

The camp will take place from August 23-25.  Here's a description from the Parkour Visions site:
"This summer, return to the source of human movement with Parkour Visions as we explore the natural environment in and around Bellingham, WA. Rafe Kelley will introduce you to the benefits of training and playing in nature. You will learn how to adapt your technique and movement to moving effectively through woods, over rocks, and in trees during this unique, 3-day experience."
Watch this video if you want to see what you're in for.

Knowing Rafe, it will be fun and productive.  You can sign up through this page.

How can carrying some extra body fat be healthy?


Most of the empirical investigations into the association between body mass index (BMI) and mortality suggest that the lowest-mortality BMI is approximately on the border between the normal and overweight ranges. Or, as Peter put it (): "Getting fat is good."

As much as one may be tempted to explain this based only on the relative contribution of lean body mass to total weight, the evidence suggests that both body fat and lean body mass contribute to this phenomenon. In fact, the evidence suggests that carrying some extra body fat may be healthy for many.

Yet, the scientific evidence strongly suggests that body fat accumulation beyond a certain point is unhealthy. There seems to be a sweet spot of body fat percentage, and that sweet spot may vary a lot across different individuals.

One interesting aspect of most empirical investigations of the association between BMI and mortality is that the participants live in urban or semi-urban societies. When you look at hunter-gatherer societies, the picture seems to be a bit different. The graph below shows the distribution of BMIs among males in Kitava and Sweden, from a study by Lindeberg and colleagues ().



In Sweden, a lowest mortality BMI of 26 would correspond to a point on the x axis that would rise up approximately to the middle of the distribution of data points from Sweden in the graph. It is reasonable to assume that this would also happen in Kitava, in which case the lowest mortality BMI would be around 20.

One of the key differences between urbanites and hunter-gatherers is the greater energy expenditure among the latter; hunter-gatherers generally move more. This provides a clue as to why some extra body fat may be healthy among urbanites. Hunter-gatherers spend more energy, so they have to consume more “natural” food, and thus more nutrients, to maintain their lean body mass.

A person’s energy expenditure is strongly dependent on a few variables, including body weight and physical activity. Let us assume that a hunter-gatherer, due to a reasonably high level of physical activity, maintains a BMI of 20 while consuming 3,000 kilocalories (a.k.a. calories) per day. An urbanite with the same height, but a lower level of physical activity, may need a higher body weight, and thus a higher BMI, to consume 3,000 calories per day at maintenance.

And why would someone want to consume 3,000 calories per day? Why not 1,500? The reason is nutrient intake, particularly micronutrient intake – intake of vitamins and minerals that are used by the body in various processes. Unfortunately it seems that micronutrient supplementation (e.g., a multivitamin pill) is largely ineffective except in cases of pathological deficiency.

Urbanites may need to carry a bit of extra body fat to be able to have an appropriate intake of micronutrients to maintain their lean body structures in a healthy state. Obviously the type of food eaten matters a lot. A high nutrient-to-calorie ratio is generally desirable. However, we cannot forget that we also need to eat fat, in part because without it we cannot properly absorb the all-important fat-soluble vitamins. And dietary fat is the most calorie-dense nutrient of all.

Why not putting on extra muscle instead of carrying the extra fat? For one, that is not easy when you are a sedentary urbanite. Particularly after a certain age, if you try too hard you end up getting injured. But there is another interesting angle to consider. Humans, like many other animals, have genetic “protections” against high muscularity, such as the protein myostatin. Myostatin is produced mostly in muscle cells; it acts on muscle, by inhibiting its growth.

Say what? Why would evolution favor something like myostatin? Big, muscular humans could be at the top of the food chain by physical strength alone; they could kill a lion with their bare hands. Well, it is possible. (Many men like to think of themselves as warriors, probably because most of them are not.) But evolution favors what works best given the ecological niches available. In our case, it favored bigger and more plastic brains to occupy what Steve Pinker called a “cognitive niche”.

Even though fat mass is not inert, secreting a number of hormones into the bloodstream, the micronutrient “need” of fat mass is likely much lower than the micronutrient need of non-fat mass. That is, a kilogram of lean mass likely puts a higher demand on micronutrients than a kilogram of fat mass. This should be particularly the case for organs, such as the liver, but also applies to muscle tissue.

While gaining muscle mass through moderate exercise is extremely healthy, bulking up beyond one’s natural limitations may actually backfire. It could increase the demand for micronutrients above what a person can actually consume and absorb through a healthy nutritious diet. Some extra fat mass allows for a higher level of micronutrient intake at weight maintenance, with a lower demand for micronutrients than the same amount of extra lean mass.

Some people are naturally more muscular. Their frame and underlying organ-based capabilities probably support that. It is often visibly noticeable when they go beyond their organ-based capabilities. A common trait among many professional bodybuilders, who usually go beyond the genetic gifts that they naturally have, is an abnormal swelling of internal organs.

What complicates this discussion is that all of this seems to vary from individual to individual. People have to find their sweet spots, and doing that may not be the simplest of tasks. For example, even measuring body fat percentage with some precision is difficult and costly. Also, certain types of fat are less desirable than others – visceral versus subcutaneous body fat. It is not easy differentiating one from the other ().

How do you find your sweet spot in terms of body fat percentage? One of the most promising approaches is to find the point at which your waist-to-weight ratio is minimized ().

Tuesday, July 2, 2013

The Genetics of Obesity, Part II

Rodents Lead the Way

The study of obesity genetics dates back more than half a century.  In 1949, researchers at the Jackson Laboratories identified a remarkably fat mouse, which they determined carried a spontaneous mutation in an unidentified gene.  They named this the "obese" (ob/ob) mouse.  Over the next few decades, researchers identified several other genetically obese mice with spontaneous mutations, including diabetic (db/db) mice, "agouti" (Avy) mice, and "Zucker" (fa/fa) rats.

At the time of discovery, no one knew where the mutations resided in the genome.  All they knew is that the mutations were in single genes, and they resulted in extreme obesity.  Researchers recognized this as a huge opportunity to learn something important about the regulation of body fatness in an unbiased way.  Unbiased because these mutations could be identified with no prior knowledge about their function, therefore the investigators' pre-existing beliefs about the mechanisms of body fat regulation could have no impact on what they learned.  Many different research groups tried to pin down the underlying source of dysfunction: some thought it was elevated insulin and changes in adipose tissue metabolism, others thought it was elevated cortisol, and a variety of other hypotheses.

Read more »

Monday, July 1, 2013

An illustration of the waist-to-weight ratio theory: The fit2fat2fit experiment


In my previous blog post, I argued that one’s optimal weight may be the one that minimizes one’s waist-to-weight ratio. I built this argument based on the fact that body fat percentage is associated with lean body mass (and also weight) in a nonlinear way.

The fit2fat2fit experiment (), provides what seems to be an interestingly way to put this optimal waist-to-weight ratio theory to test. This is due to a fortuitous event, as I explain in this post.

In this experiment, Drew Manning, a personal trainer, decided to undergo a transformation where he went from what he argued was his fittest level, all the way to obese, and then back to fit again. He said that he wanted to do that so that he could better understand his clients’ struggles. This may be true, but it looks like he planned very well his experiment from a marketing perspective.

His fittest level was at the start, with a weight of 193 lbs, at a height of 6 ft 2 in. That was his fittest level according to his own opinion. At that point, he had a waist of 34.5 in, and looked indeed very fit (). At his fattest level, he reached the weight of 264.8 pounds, with a 47.5 waist.

As he moved back to fit, one interesting thing happened. Toward the end of this journey back to fit, he moved past the level that he felt was his optimal. He dropped down to 190.1 lbs, and a 34 in waist; which he perceived as too skinny. He talks about this in a video ().

As a self-defined “fanatic” personal trainer, I figured that he knew when he had gone too far. That is, he is probably as qualified as one can get to identify the point at which he moved past his optimal. So I thought that this would be an interesting way of putting my optimal waist-to-weight ratio theory to the test.

Below is a bar chart showing variations in waist-to-weight ratio against weight for Drew Manning during his fit2fat2fit experiment. I included only three data points in this chart because I would have to view all of his video clips to get all of the data points.



As you can see, at the point at which he felt he was too thin, his waist-to-weight ratio clearly started going up from what seems to have been its optimal at 34.5 in / 193 lbs. This is exactly what you would expect based on my optimal waist-to-weight ratio theory. You probably can’t tell that something was not right at that point, because he looked very fit.

But apparently he felt that something was not entirely right. And that is consistent with the idea that he had passed his optimal waist-to-weight ratio, and became too lean for his own good. Note that his waist decreased, and probably could go down even further, even though that was no longer optimal.