Showing posts with label exercise. Show all posts
Showing posts with label exercise. Show all posts

What Causes Insulin Resistance? Part VII

Monday, January 23, 2012

In previous posts, I outlined the factors I'm aware of that can contribute to insulin resistance.  In this post, first I'll list the factors, then I'll provide my opinion of effective strategies for preventing and potentially reversing insulin resistance.

The factors

These are the factors I'm aware of that can contribute to insulin resistance, listed in approximate order of importance.  I could be quite wrong about the order-- this is just my best guess. Many of these factors are intertwined with one another. 
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What Causes Insulin Resistance? Part VI

Wednesday, January 18, 2012

In this post, I'll explore a few miscellaneous factors that can contribute to insulin resistance: smoking, glucocorticoids/stress, cooking temperature, age, genetics and low birth weight.

Smoking

Smoking tobacco acutely and chronically reduces insulin sensitivity (1, 2, 3), possibly via:
  1. Increased inflammation
  2. Increased circulating free fatty acids (4)
Paradoxically, since smoking also protects against fat gain, in the very long term it may not produce as much insulin resistance as one would otherwise expect.  Diabetes risk is greatly elevated in the three years following smoking cessation (5), and this is likely due to the fat gain that occurs.  This is not a good excuse to keep smoking, because smoking tobacco is one of the most unhealthy things you can possibly do.  But it is a good reason to tighten up your diet and lifestyle after quitting.

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A Roadmap to Obesity

Thursday, August 25, 2011

In this post, I'll explain my current understanding of the factors that promote obesity in humans.  

Heritability

To a large degree, obesity is a heritable condition.  Various studies indicate that roughly two-thirds of the differences in body fatness between individuals is explained by heredity*, although estimates vary greatly (1).  However, we also know that obesity is not genetically determined, because in the US, the obesity rate has more than doubled in the last 30 years, consistent with what has happened to many other cultures (2).  How do we reconcile these two facts?  By understanding that genetic variability determines the degree of susceptibility to obesity-promoting factors.  In other words, in a natural environment with a natural diet, nearly everyone would be relatively lean, but when obesity-promoting factors are introduced, genetic makeup determines how resistant each person will be to fat gain.  As with the diseases of civilization, obesity is caused by a mismatch between our genetic heritage and our current environment.  This idea received experimental support from an interesting recent study (3).

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Natural cures looks at the circulation theory

Thursday, January 27, 2011

Natural cures are found though the circulation system. The circulatory system of the human anatomy is in many respects a transportation system. Oxygen fixated upon red blood cells in the lungs is transported in the bloodstream to every cell in the body. The wastes eliminated by cells are conveyed through the bloodstream to the excretory system, which excretes the wastes but saves the blood cells for further utilization. Nutrients are also conveyed from the intestine to the cells through the bloodstream.
When circulation of the blood is impeded, the body is besieged by problems. Upon the delay of nutrients or oxygen, cells die from the lack of sustenance. Upon the impediment of blood flow, efficiency of cellular waste eliminanation is greatly reduced, and upon the accumulation of waste matter due to cellular dysfunction, health problems develop.
This would lead some people to conclude that increasing the rate of circulation will decrease  the chances of problems developing inside the body. The method that comes to most peoples minds as appropriate for accelerating the circulation is exercise.









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Book Review: The Primal Blueprint

Wednesday, March 17, 2010

Mark Sisson has been a central figure in the evolutionary health community since he began his weblog Mark's Daily Apple in 2006. He and his staff have been posting daily on his blog ever since. He has also written several other books, edited the Optimum Health newsletter, competed as a high-level endurance athlete, and served on the International Triathlon Union as the anti-doping chairman, all of which you can read about on his biography page. Mark is a practice-what-you-preach kind of guy, and if physical appearance means anything, he's on to something.

In 2009, Mark published his long-awaited book The Primal Blueprint. He self-published the book, which has advantages and disadvantages. The big advantage is that you aren't subject to the sometimes onerous demands of publishers, who attempt to maximize sales at Barnes and Noble. The front cover sports a simple picture of Mark, rather than a sunbaked swimsuit model, and the back cover offers no ridiculous claims of instant beauty and fat loss.

The drawback of self-publishing is it's more difficult to break into a wider market. That's why Mark has asked me to publish my review of his book today. He's trying to push it up in the Amazon.com rankings so that it gets a broader exposure. If you've been thinking about buying Mark's book, now is a good time to do it. If you order it from Amazon.com on March 17th, Mark is offering to sweeten the deal with some freebies on his site Mark's Daily Apple. Full disclosure: I'm not getting anything out of this, I'm simply mentioning it because I was reviewing Mark's book anyway and I thought some readers might enjoy it.

The Primal Blueprint is not a weight loss or diet book, it's a lifestyle program with an evolutionary slant. Mark uses the example of historical and contemporary hunter-gatherers as a model, and attempts to apply those lessons to life in the 21st century. He does it in a way that's empowering accessible to nearly everyone. To illustrate his points, he uses the example of an archetypal hunter-gatherer called Grok, and his 21st century mirror image, the Korg family.

The diet section will be familiar to anyone who has read about "paleolithic"-type diets. He advocates eating meats including organs, seafood, eggs, nuts, abundant vegetables, and fruit. He also suggests avoiding grains, legumes, dairy (although he's not very militant about this one), processed food in general, and reducing carbohydrate to less than 150 grams per day. I like his diet suggestions because they focus on real food. Mark is not a drill sergeant. He tries to create a plan that will be sustainable in the long run, by staying positive and allowing for cheats.

We part ways on the issue of carbohydrate. He suggests that eating more than 150 grams of carbohydrate per day leads to fat gain and disease, whereas I feel that position is untenable in light of what we know of non-industrial cultures (including some relatively high-carbohydrate hunter-gatherers). Although carbohydrate restriction (or at least wheat and sugar restriction) does have its place in treating obesity and metabolic dysfunction in modern populations, ultimately I don't think it's necessary for the prevention of those same problems, and it can even be counterproductive in some cases. Mark does acknowledge that refined carbohydrates are the main culprits.

The book's diet section also recommends nutritional supplements, including a multivitamin/mineral, antioxidant supplement, probiotics, protein powder and fish oil. I'm not a big proponent of supplementation. I'm also a bit of a hypocrite because I do take small doses of fish oil (when I haven't had seafood recently), and vitamin D in wintertime. But I can't get behind protein powders and antioxidant supplements.

Mark's suggestions for exercise, sun exposure, sleep and stress management make good sense to me. In a nutshell: do all three, but keep the exercise varied and don't overdo it. As a former high-level endurance athlete, he has a lot of credibility here. He puts everything in a format that's practical, accessible and empowering.

I think The Primal Blueprint is a useful book for a person who wants to maintain or improve her health. Although we disagree on the issue of carbohydrate, the diet and lifestyle advice is solid and will definitely be a vast improvement over what the average person is doing. The Primal Blueprint is not an academic book, nor does it attempt to be. It doesn't contain many references (although it does contain some), and it won't satisfy someone looking for an in-depth discussion of the scientific literature. However, it's perfect for someone who's getting started and needs guidance, or who simply wants a more comprehensive source than reading blog snippets. It would make a great gift for that family member or friend who's been asking how you stay in such good shape.

Book Review: S.P.E.E.D.

Monday, March 1, 2010

This book was sent to me by Matt Schoeneberger, who co-authored it with Jeff Thiboutot. Both have master's degrees in exercise science and health promotion. S.P.E.E.D. stands for Sleep, Psychology, Exercise, Environment and Diet. The authors have attempted to create a concise, comprehensive weight loss strategy based on what they feel is the most compelling scientific evidence available. It's subtitled "The Only Weight Loss Book Worth Reading". Despite the subtitle that's impossible to live up to, it was an interesting and well-researched book. It was a very fast read at 205 large-print pages including 32 pages of appendices and index.

I really appreciate the abundant in-text references the authors provided. I have a hard time taking a health and nutrition book seriously that doesn't provide any basis to evaluate its statements. There are already way too many people flapping their lips out there, without providing any outside support for their statements, for me to tolerate that sort of thing. Even well-referenced books can be a pain if the references aren't in the text itself. Schoeneberger and Thiboutot provided appropriate, accessible references for nearly every major statement in the book.

Chapter one, "What is a Healthy Weight", discusses the evidence for an association between body weight and health. They note that both underweight and obesity are associated with poor health outcomes, whereas moderate overweight isn't. While I agree, I continue to maintain that being fairly lean and appropriately muscled (which doesn't necessarily mean muscular) is probably optimal. The reason that people with a body mass index (BMI) considered to be "ideal" aren't healthier on average than people who are moderately overweight may have to do with the fact that many people with an "ideal" BMI are skinny-fat, i.e. have low muscle mass and too much abdominal fat.

Chapter 2, "Sleep", discusses the importance of sleep in weight regulation and overall health. They reference some good studies and I think they make a compelling case that it's important. Chapter 3, "Psychology", details psychological strategies to motivate and plan for effective weight loss.

Chapter 4, "Exercise", provides an exercise plan for weight loss. The main message: do it! I think they give a fair overview of the different categories of exercise and their relative merits, including high-intensity intermittent training (HIIT). However, the exercise regimen they suggest is intense and will probably lead to overtraining in many people. They recommend resistance training major, multi-joint exercises, 1-3 sets to muscular failure 2-4 days a week. I've been at the higher end of that recommendation and it made my joints hurt, plus I was weaker than when I strength trained less frequently. I think the lower end of their recommendation, 1 set of each exercise to failure twice a week, is more than sufficient to meet the goal of maximizing improvements in body composition in most people. My current routine is one brief strength training session and one sprint session per week (in addition to my leisurely cycle commute), which works well for me on a cost-benefit level. However, I was stronger when I was strength training twice a week and never going to muscular failure (a la Pavel Tsatsouline).

Chapter 5, "Environment", is an interesting discussion of different factors that promote excessive calorie intake, such as the setting of the meal, the company or lack thereof, and food presentation. While they support their statements very well with evidence from scientific studies, I do have a lingering doubt about these types of studies: as far as I know, they're all based on short-term interventions. Science would be a lot easier if short-term always translated to long term, but unfortunately that's not the case. For example, studies lasting one or two weeks show that low glycemic index foods cause a reduction in calorie intake and greater feelings of fullness. However, this effect disappears in the long term, and numerous controlled trials show that low glycemic index diets have no effect on food intake, body weight or insulin sensitivity in the long term. I reviewed those studies here.

The body has homeostatic mechanisms (homeostatic = maintains the status quo) that regulate long-term energy balance. Whether short-term changes in calorie intake based on environmental cues would translate into sustained changes that would have a significant impact on body fat, I don't know. For example, if you eat a meal with your extended family at a restaurant that serves massive portions, you might eat twice as much as you would by yourself in your own home. But the question is, will your body factor that huge meal into your subsequent calorie intake and energy expenditure over the following days? The answer is clearly yes, but the degree of compensation is unclear. Since I'm not aware of any trials indicating that changing meal context can actually lead to long-term weight loss, I can't put much faith in this strategy (if you know otherwise, please link to the study in the comments).

Chapter 6, "Diet", is a very brief discussion of what to eat for weight loss. They basically recommend a low-calorie, low-carb diet focused on whole, natural foods. I think low-carbohydrate diets can be useful for some overweight people trying to lose weight, if for no other reason than the fact that they make it easier to control appetite. In addition, a subset of people respond very well to carbohydrate restriction in terms of body composition, health and well-being. The authors emphasize nutrient density, but don't really explain how to achieve it. It would have been nice to see a discussion of a few topics such as organ meats, leafy greens, dairy quality (pastured vs. conventional) and vitamin D. These may not help you lose weight, but they will help keep you healthy, particularly on a calorie-restricted diet. The authors also recommend a few energy bars, powders and supplements that I don't support. They state that they have no financial connection to the manufacturers of the products they recommend.

I'm wary of their recommendation to deliberately restrict calorie intake. Although it will clearly cause fat loss if you restrict calories enough, it's been shown to be ineffective for sustainable, long-term fat loss over and over again. The only exception is the rare person with an iron will who is able to withstand misery indefinitely. I'm going to keep an open mind on this question though. There may be a place for deliberate calorie restriction in the right context. But at this point I'm going to require some pretty solid evidence that it's effective, sustainable, and doesn't have unacceptable side effects.

The book contains a nice bonus, an appendix titled "What is Quality Evidence"? It's a brief discussion of common logical pitfalls when evaluating evidence, and I think many people could benefit from reading it.

Overall, S.P.E.E.D. was a worthwhile read, definitely superior to 95% of fat loss books. With some caveats mentioned above, I think it could be a useful resource for someone interested in fat loss.
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