New Post on Eat Move Sleep Blog

Yesterday, the Dan's Plan blog Eat Move Sleep published a blog post I wrote about sleep, artificial light, your brain, and a free computer program called f.lux that can help us live healthier lives.  Head over to Eat Move Sleep to read it.

Sleep and Genetic Obesity Risk

Evidence is steadily accumulating that insufficient sleep increases the risk of obesity and undermines fat loss efforts.  Short sleep duration is one of the most significant risk factors for obesity (1), and several potential mechanisms have been identified, including increased hunger, increased interest in calorie-dense highly palatable food, reduced drive to exercise, and alterations in hormones that influence appetite and body fatness.  Dan Pardi presented his research at AHS13 showing that sleep restriction reduces willpower to make healthy choices about food.

We also know that genetics has an outsized influence on obesity risk, accounting for about 70 percent of the variability in body fatness between people in affluent nations (2).  I have argued that "fat genes" don't directly lead to obesity, but they do determine who is susceptible to a fattening environment and who isn't (3).  I recently revisited a 2010 paper published in the journal Sleep by University of Washington researchers that supports this idea (4).

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Ancestral Health Symposium 2012: Evolutionarily sound diets and lifestyles may revolutionize health care

The Ancestral Health Symposium 2012 was very interesting on many levels. Aaron Blaisdell and the team of volunteers really did a superb job at organizing the Symposium. Boston is a great city with an excellent public transportation system, something that is always great for meetings, and a great choice for the Symposium. Needless to say, so was Harvard. Even though the program was packed there were plenty of opportunities to meet and talk with several people during the breaks.

We had our panel “New Technologies and New Opportunities”, which Paul Jaminet moderated. The panelists were Chris Keller, Chris Kresser, Dan Pardi, and myself. The first photo below, by Bobby Gill, shows Chris Keller speaking; I am on the far left looking at the screen. The second photo, by Beth Mazur, shows all the panelists. The third photo, also by Bobby Gill, shows a group of us talking to Stephan Guyenet after his presentation.

I talked a bit toward the end of the panel about the importance of taking nonlinearity into consideration in analyses of health data, but ended up being remembered later for saying that “men are women with a few design flaws”. I said that to highlight the strong protective effect of being female in terms of health, which was clear from the model I was discussing.

There is a good evolutionary reason for the protective effect of being female. Evolution is a population phenomenon. Genes do not evolve; neither do individuals. Populations evolve through the spread or disappearance of genotypes. A healthy population with 99 men and 1 woman will probably disappear quickly, and so will its gene pool. A healthy population with 99 women and 1 man will probably thrive, even with the drag of inbreeding depression. Under harsh environmental conditions, the rate of female-to-male births goes up, in some cases quite a lot.

I was able to talk to, or at least meet briefly face-to-face with, many of the people that I have interacted with online on this blog and other blogs. Just to name a few: Miki Ben-Dor, Aaron Blaisdell, Emily Deans, Andreas Eenfeldt, Glenn Ellmers, Benjamin Gebhard, Stephan Guyenet, Dallas Hartwig, Melissa Hartwig, Paul Jaminet, Chris Keller, Chris Kresser, Mathieu Lalonde, Robert Lustig, Chris Masterjohn, Beth Mazur, Denise Minger, Jimmy Moore, Katherine Morrison, Richard Nikoley, Dan Pardi, Kamal Patel, David Pendergrass, Mark Sisson, Mary Beth Smrtic, J. Stanton, Carlos Andres Toro, and Grayson Wheatley.

It would have been nice to have Peter (from Hyperlipid) there, as I think a lot of the attendants are fans. I attended Jamie Scott’s very interesting talk, but ended up not being able to chat with him. This is a pity because we share some common experiences – e.g., I lived in New Zealand for a few years. I did have the opportunity to talk at some length with J. Stanton, who is an inspiration. It was also great to exchange some ideas with my panelists, Miki Ben-Dor, Emily Deans, Stephan Guyenet, Chris Masterjohn, Kamal Patel, and David Pendergrass. I wish I had more time to talk with Denise Minger, who is clearly a very nice person in addition to being very smart. Talking about a smart person, it was also nice chatting a bit with Richard Nikoley; a successful entrepreneur who is in the enviable position of doing what he feels like doing.

I could not help but notice a tendency among some participants (perhaps many, judging from online threads) to pay a lot of attention to how other people looked in a very judgmental way. That person is too fat, his/her face is too red, she/he looks too old etc. So was this supposed to be the Ancestral Health Pageant 2012? There is nothing wrong with looking good. But many people adopt an evolution-inspired lifestyle because they are quite unhealthy to start with. And this includes some of the presenters. It takes time to change one’s health, relapses occur, and no one is getting younger. Moreover, some of the presenters’ ideas and advice may have much more dramatic positive effects on people other than themselves, because of their own pre-existing conditions. The ideas and advice are still solid.

A message that I think this Symposium conveyed particularly well was that an evolutionarily sound diet and lifestyle can truly revolutionize our health care system. Robb Wolf’s talk in particular, based on his recent experience in Nevada with law enforcement officers, made this point very effectively. The title of the talk is “How Markets and Evolution Can Revolutionize Medicine”. One very interesting idea he put forth was that establishments like gyms could expand the range of support activities they offer their customers, officially becoming the beginning of the health care chain. There are already health insurance plans that offer premium reductions for those who go to gyms. Being part of the health care chain would be different and a significant step forward - diet and exercise are powerful "drugs".

One thing that caught me a bit off-guard was Robb’s strong advocacy of the use of a drug, namely metformin (a.k.a. glucophage); even preventively in some special cases, such as with sleep-deprived law enforcement officers. I have to listen to that talk again when it is up online, to make sure that I understood it correctly. It seems to me that changing the nature of shift work among law enforcement officers, at least partially, may be a better target; current practices appear not only to impair the officers’ health but also their effectiveness in law enforcement activities. Besides, I think we need to better understand the nature and functions of cortisol, which is viewed by many as a hormone that exists only to do us harm.

Sleep deprivation is associated with an elevation in cortisol production. Elevated cortisol levels lead over time to visceral fat accumulation, which promotes systemic inflammation. Systemic inflammation is possibly the root cause of most diseases of civilization. But cortisol itself has powerful anti-inflammatory properties, and visceral fat is generally easy to mobilize through intense exercise – probably one of the key reasons why we have visceral fat. I think we need to understand this situation a bit better before thinking about preventive uses of metformin, which nevertheless is a drug that seems to do wonders in the treatment of type 2 diabetes.

Beth Mazur was kind enough to put up a post with links to various Ancestral Health Symposium 2012 summary posts, as well as pictures. Paul Jaminet has a post with an insightful discussion of our panel at the Symposium.

The Big Sleep

This blog usually focuses on diet, because that's my specialty. But if you want Whole Health, you need the whole package: a diet and lifestyle that is broadly consistent with our evolutionary heritage. I think we all know that on some level, but a recent paper has reminded me of it.

I somehow managed to get on the press list of the Annals of Internal Medicine. That means they send me embargoed papers before they're released to the general public. That journal publishes a lot of high-impact diet studies, so it's a great privilege for me. I get to write about the studies, and publish my analysis at the time of general release, which is the same time the news outlets publish their stories.

One of the papers they sent me recently is a fat loss trial with an interesting twist (1; see below). All participants were told to eat 10% fewer calories that usual for two weeks, however half of them were instructed to sleep for 8 and a half hours per night, and the other half were instructed to sleep for 5 and a half hours*. The actual recorded sleep times were 7:25 and 5:14, respectively.

Weight loss by calorie restriction causes a reduction of both fat and lean mass, which is what the investigators observed. Both groups lost the same amount of weight. However, 80% of the weight was lost as fat in the high-sleep group (2.4/3.0 kg lost as fat), while only 48% of it was lost as fat in the low-sleep group (1.4/2.9 kg lost as fat). Basically, the sleep-deprived group lost as much lean mass as they did fat mass, which is not good!

There are many observational studies showing associations between insufficient sleep, obesity and diabetes. However, I think studies like that are particularly vulnerable to confounding variables, so I've never known quite what to make of them. Furthermore, they often show that long sleep duration associates with poor health as well, which I find highly unlikely to reflect cause and effect. I discussed one of those studies in a post a couple of years ago (2). That's why I appreciate this controlled trial so much.

Another sleep restriction trial published in the Lancet in 1999 showed that restricting healthy young men to four hours of sleep per night caused them to temporarily develop glucose intolerance, or pre-diabetes (3).

Furthermore, their daily rhythm of the hormone cortisol became abnormal. Rather than the normal pattern of a peak in the morning and a dip in the evening, sleep deprivation blunted their morning cortisol level and enhanced it in the evening. Cortisol is a stress hormone, among other things, and its fluctuations may contribute to our ability to feel awake in the morning and ready for bed at night.

The term "adrenal fatigue", which refers to the aforementioned disturbance in cortisol rhythm, is characterized by general fatigue, difficulty waking up in the morning, and difficulty going to sleep at night. It's a term that's commonly used by alternative medical practitioners but not generally accepted by mainstream medicine, possibly because it's difficult to demonstrate and the symptoms are fairly general. Robb Wolf talks about it in his book The Paleo Solution.

The investigators concluded:

Sleep debt has a harmful impact on carbohydrate metabolism and endocrine function. The effects are similar to those seen in normal ageing and, therefore, sleep debt may increase the severity of age-related chronic disorders.

So there you have it. Besides making us miserable, lack of sleep appears to predispose to obesity and diabetes, and probably sets us up for the Big Sleep down the line. I can't say I'm surprised, given how awful I feel after even one night of six hour sleep. I feel best after 9 hours, and I probably average about 8.5. Does it cut into my free time? Sure. But it's worth it to me, because it allows me to enjoy my day much more.

Keep your room as dark as possible during sleep. It also helps to avoid bright light, particularly in the blue spectrum, before bed (4). "Soft white" bulbs are preferable to full spectrum in the evening. If you need to use your computer, dim the monitor and adjust it to favor warm over cool colors. For people who sleep poorly due to anxiety, meditation before bed can be highly effective. I posted a tutorial here.

1. Nedeltcheva, AV et al. "Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity." Annals of Internal Medicine. 2010. Advanced publication.


* The study was a randomized crossover design with a 3 month washout period, which I consider a rigorous design. I think the study overall was very clever. The investigators used calorie restriction to cause rapid changes in body composition so that they could see differences on a reasonable timescale, rather than trying to deprive people of sleep for months and look for more gradual body fat changes without dietary changes. The latter experiment would have been more interesting, but potentially impractical and unethical.