Wednesday, October 9, 2013

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).


Dr. Nathaniel Watson and colleagues used twins to tease apart what proportion of obesity risk is due to genes vs. environment, and if sleep duration influences that relationship.  Consistent with other studies, genetics explained 60 percent of the variability in body fatness between participants.  Also consistent with other studies, people who slept less tended to be fatter.  However, what sets this study apart is that they determined how sleep duration influences the relationship between genetics and body fatness.

What they found is nothing short of remarkable.  In people sleeping less than 7 hours per night, genetics determined 70 percent of body fatness, while the environment (lifestyle/diet and 'random' effects) explained only 30 percent.  In people sleeping more than 9 hours per night, genetics only explained 32 percent of body fatness, while environment explained 68 percent.  In other words, in people who sleep more than 9 hours, the environment and not genes was the primary determinant of body fatness.

The result was summarized in the following graph:


According to the authors, short sleep duration appears to favor the expression of genetic risk factors for obesity:
Our work suggests latent genetic variability in susceptibility to obesity requires activation by sleep curtailment.
In other words, in an obesity-promoting (low-sleep) environment, people who are genetically susceptible to obesity gain fat, while in a non-obesity-promoting (high-sleep) environment, genetic risk factors are less relevant and don't influence body fatness as much.  "Obesity genes" act primarily in an obesity-promoting environment.

As a whole, I find the sleep-obesity research quite compelling.  This is one of the reasons why the Ideal Weight Program focuses on improving sleep quantity and quality, a strategy that sets it apart from nearly every other fat loss program.  We combine a tracking system that provides consistent objective feedback on sleep habits, with sleep guidance that helps overcome barriers to restorative sleep.


23 comments:

Wanna Be Mother said...

I think insomnia is linked to genes too so could it be that genes are also causing the lack of sleep in some of the people not sleeping and thus the % due to genes ? I wish I could sleep 9 hours a night but I'm lucky if I can get 6 or 7 good solid hours of sleep and I'm pretty sure there is some genetics that cause the lack of sleep. But there are also genetics for obesity in my family. Do those genes overlap? Biology is so complicated.

Stephan Guyenet said...

Hi WBM,

You're asking good questions. The authors also reported that sleep duration is genetically influenced. I wouldn't be surprised if sleep and obesity genes overlap somewhat, but to my knowledge it isn't currently known.

FeelGoodEating said...

Epigenetics?

Thank you Stephan for your continued sharing of first class information.

Marc

William said...

What about individuals not susceptible to obesity? I know quite a few rail thin and even visually "fit" insomniacs or just chronic undersleepers. I myself struggle with sleep on and off all the time and haven't noticed weight gain. That said, I eat the same almost everyday and have been eating a whole food diet for quite sometime. Obviously, for most folks, this is not the case.

That said, many of these skinny non-sleepers I know eat fairly poorly. However, as would be expected, their portions are quite small. Their diets also lean towards sugar and caffiene rather than fat + protein.

Marty said...

Talking about first class information - I have been on a 'sleep is important' kick lately as well and I am glad to see that you have posted on this important topic. I see that there is some controversy re: T.S. Wiley's work. Since she wrote the book 'Lights Out: sleep, sugar (etc.)' (a book that thoroughly discusses sleep from an ancestral approach) and Robb Wolf seems to endorse her, I was wondering what you think about her work. She apparently is doing a lot with with bio-identical hormones and most Paleo folks don't discuss this line of thinking. Do you think more needs to be done in regards to sleep problems than quality diets, exercise - such as hormones? Or should we not mess with ingesting additional hormones? Thanks for your help with this; I have always respected your work and greatly appreciate your talks with AHS and TedX.

Logan said...

I suspect an overstimulating environment has much to do with our sleep disturbances in the US. Iread a study somewhere a little while back on a group of men removed from artificial light for a period slept for a week or two a great quantity every night in a sort of catch-up period (12-13hrs/night) and then transitioned to a regular 9hr schedule naturally.
Interesting I just moved to west Africa and in the absence of regular power and with it Tv or Internet I noticed our whole family went through a similar adjustment. Sleeping the first three weeks sometimes up to 14 hours. Now for the past months holding at between 8-10hours a night. We have lost weight too! We weren't obese by any means but pounds have flown and low food reward is definitely a factor as is
dysentary! :)
sorry for this being vaguely incoherant english-I'm thinking in pidgin these days!

Logan said...

Also I hope the Lisbon talk went well! I hope you post your notes on it it sounded very interesting. Thanks for all your contributions here I am really grateful to your insights!

Grinch said...

Another defeat of the eat less, move more nonsense. If you sleep less, shouldn't you be burning more calories because you are awake and moving around more?

Greenacres said...

I wonder if sleep apnea was also considered. I have untreated apnea, and can easily sleep 10 hours, but presumably that is low quality sleep. If I lost a hundred pounds the apnea might go away, but it sounds like the poor sleep could be a factor in my difficulty losing weight.

William Mullan said...

What about those folks who are less susceptible to obesity?

When the sleep issue comes up, I often think of people like Qi Lu and myself. Qi Lu reportedly figured out how to only get 4 hours a sleep a night while being actively physically and mentally. He's pretty darn thin. I myself am quite lean and often struggle with getting more than 6 hours of sleep and have been averaging one all-nighter a month for a few months now (sadly). This not voluntary like Mr. Lu's (although sometimes I figure I might as well except it and use the time productively rather than stressing over the lost sleep), but it hasn't added weight to me. If anything, I loose weight. However, I eat a whole food diet and take Curcumin and eat very dark chocolate since both have been shown to prevent some of the negative changes in the brain and body that are associated with sleep deprivation.

Perhaps Qi and I are just outliers. Seems to be the most likely answer.

Cohen Ilan said...

Sleep is so important, and many people don't know it

karl said...

Of course less sleep means less time spent in ketosis. Then again it is sort of hard to eat in one's sleep..

Of course we know about all the papers the point to the association of the disruption of the insulin system and the lack of sleep.

There are probably 10 other effects that are also correlated with the lack of sleep - assigning cause is a good way to get egg on your face - lots of cross correlations.. Then there is the pesky issue of the direction of the causation arrow.

Correlations are not useful if they don't get followed up with careful controlled studies.

jeff thiboutot said...

Thanks for sharing this information and highlighting the importance of sleep. I am glad to see more research coming out connecting sleep quantity and quality with health and weight regulation. When Matt and I wrote our book a few years ago, we felt that sleep was very important and often overlooked when it came to weight management, that's why we wrote a whole chapter on it.

Charles L. Peden said...

Maybe I am misunderstanding, but the idea of this article seems backwards.

When I was a teenager (and not obese) my mother took me to a doctor because I was sleeping so much. She thought I might have mono. The doctor's diagnosis? He said I was just lazy (!!!).

Now that I am obese I am lucky to get 4 hours of sleep per night. I have had sleep studies showing sleep apnea and I have obtained a cpap machine (which I don't use) and a dental device (which I also don't use). Several thousands of dollars wasted. I know what the problem is, it is my weight causing the sparse sleep not vice-versa.

It's the same thing with physical activity. I move less and get out less because of my weight not vice-versa. I got a much more physically active job and it did NOTHING for my weight. There were plenty of obese people working at the same job.

Poor sleep and reduced physical activity are clearly SYMPTOMS of, not causes of obesity.

Jane said...

Interesting paper published in Science today about sleep.

Sleep Drives Metabolite Clearance from the Adult Brain
http://www.sciencemag.org/content/342/6156/373

The conservation of sleep across all animal species suggests that sleep serves a vital function. We here report that sleep has a critical function in ensuring metabolic homeostasis. Using real-time assessments of tetramethylammonium diffusion and two-photon imaging in live mice, we show that natural sleep or anesthesia are associated with a 60% increase in the interstitial space, resulting in a striking increase in convective exchange of cerebrospinal fluid with interstitial fluid. In turn, convective fluxes of interstitial fluid increased the rate of β-amyloid clearance during sleep. Thus, the restorative function of sleep may be a consequence of the enhanced removal of potentially neurotoxic waste products that accumulate in the awake central nervous system.



Stephan Guyenet said...

Hi Charles,

Poor sleep and physical inactivity do result from obesity, as you said. But that doesn't rule out the possibility that they also contribute to it. We know that physical inactivity facilitates obesity, and obesity facilitates inactivity, so that is a two-way street.

The same is probably true of sleep. Prospective studies have shown that reduced sleep time predicts future weight gain, and it also increases calorie intake and facilitates poor food choices in controlled trials. Yet obesity can also contribute to disordered breathing during sleep. It's probably a two-way street.

But that doesn't mean short sleep duration contributes to all cases of obesity. Obesity has many causes and they aren't all present in all individuals.

nosnoozeyoulose said...

This is so interesting! I'm writing a blog: http://nosnoozeyoulose.wordpress.com/ on sleeping and the health impacts but in a more casual tone targeted at uni students with a sprinkling of humour.

This will definitely enrich and I've seen so many blogs linking sleep with obesity but a lot more solid research needs to be made.

Cathy Blackburn said...

I think we are hard wired to take eating opportunities and food manufacturers have become very efficient at providing food to stimulate our eating response. Add to this unhelpful sleep patterns, toxic load on the body from both food and outside sources and it is a recipe for disaster. This is especially true when you consider also the attitude to health these days. Too much emphasis is placed on doctors fixing us when we get sick or overweight rather than us taking responsibility and looking after our body.

Nicole Hanson said...

Having a good amount of sleep is really important. My parents usually told me that eating less every night can help in having a good sleep cause when you are bloated you feel heavy but when you eat less you feel lighter and the body is more relaxed. Having hard time sleeping is really a major problem to people. Thank you for sharing such amazing information.

jaymans said...

Yeah, I wouldn't put too much faith in this study, yet. For one, the main reason their shared environment term seems to have increased in the long sleepers is because their sample size got pretty small there (47 pairs). In general, unless you have a huge number of subjects, the confidence intervals around the shared environment are too large to for your study to be useful. In this case, as per usual in behavioral genetic studies, their confidence intervals on the shared environment, even in their "interaction" hypothesis, went down to near 0.1, or insignificance.

Of course, it's worth mentioning that you can't actually measure the shared environment from MZT-DZT studies – the extraction of the shared environment term in these studies is largely a fingle factor, and is itself confounded by assortative mating.

I'd be more impressed if these results held up in a much larger sample.

jaymans said...

In addition, and I should have said this before, you can't actually do what this study is attempting. Lumping subjects by phenotypic similarity is really taking the magic out of behavioral genetic studies: if you try to decompose ACE from twins for which you've already sorted by phenotype, you are going to confuse heritable effects (say, shared non-additive variance) with shared environment; the study will lose the power to distinguish the two.

Stephanie said...

Help! I have a four month old son who sleeps horribly. I've been sleep deprived since his birth and will probably be for a few more months until sleeps through the night. Am I doomed to never lose the baby weight? I'm normal weight but still have more fat than I'd like. I cook most of our food, lots of veggies, fruit, beans, etc. I don't snack. There isn't much energy for exercise at this point.

Mike Roberts said...

A new survey out has said that sleeping more than 8 hours per night is bad and can course a whole range of health problems including memory and even the risk of stoke, so sleeping 7 hours is just about right.