An astute commenter pointed out that I misread the numbers in the paper on sleep and fat loss. I wrote that out of the total 3.0 kg lost, the high-sleep group lost 2.4 kg as fat, and the low-sleep group lost 1.4 kg of fat out of 2.9 kg total.
In fact, the high-sleep group lost 1.4 out of 2.9 kg as fat, and the low-sleep group lost 0.6 out of 3.0 kg as fat. So I got the numbers all mixed up. Sorry for the mistake. The main point of the post still stands though: sleep deprivation negatively influences body composition.
The correct numbers are even more interesting than the ones I made up. Even in the high-sleep group, nearly half the body weight lost by simple calorie restriction was lean mass. That doesn't make calorie restriction look very good!
In the sleep-deprived group, 80% of the weight lost by calorie restriction came out of lean mass. Ouch!
That illustrates one of the reasons why I'm skeptical of simple calorie restriction as a means of fat loss. When the body "wants" to be fat, it will sacrifice lean mass to preserve fat tissue. For example, the genetically obese Zucker rat cannot be starved thin. If you try to put it on a severe calorie-restricted diet, it will literally die fat because it will cannibalize its own lean mass (muscle, heart, brain, etc.) to spare the fat. That's an extreme example, but it illustrates the point.
The key is not only to balance energy intake with expenditure (which the brain does automatically when it's working correctly), but to allocate energy appropriately to lean and fat mass.
James Krieger has a very thought provoking perspective of insulin and obesity at his "Weightology Weekly" blog.
I've always wondered if the reason the CR people get favorable results is because their restricting reduces the amount of Neolithic foods they consume.
thanks for the correction.
Just wanted to note, Chinese believe that the quality of sleep is as important as if not more important than quantity of sleep.
And the sleeping hours is seen as a very important aspect of the quality of sleeping. Ancient Chinese sleep according to the seasonal changes as well as weather changes. But the general rule is that, one should be in bed between 11 and 3, because this is the period where our bodies really cleanse ourselves, and readjust our body functions. Sleeping outside this period ,or work at night, sleep in day time, does not have the same health benefit as sleep inside this period. It could be quite damaging. It does not matter how much one sleeps after this, the quality of sleep is just low.
One of the things I've noticed is that even if I go to sleep late, if I wear a nasal strip (on my nose!), I awake more alert and refreshed, as if I had slept deeper, longer, and better. I joke that my wearing nasal strips improves my husband's snoring. He probably doesn't snore any less, I just sleep deep enough I don't hear it. I suspect nasal vs mouth breathing is a significant issue in sleep quality and duration.
Yea.. I've known a few (parkour) athletes who swear by caloric restriction.
How does coffee affect metabolism?
While learning a bit of yoga in India (which they site as being about benefitting your endocrine system, interestingly), there's a lot of practice in breathing correctly like 'sun and moon' breathing (closing one nostril with your finger, breathing in, then switching to the other nostril, breathing out... then breath in and switch) and expelling breathing (short bursts of exhaling out). Anna's reply reminded me of this and the possible importance of nasal vs mouth breathing.
@ Anna -- How interesting! That ties into the whole Weston A. Price emphasis on proper facial structure and formation. A traditional, nutrient-rich diet (particularly in young children) fosters that kind of healthy, spacious formation and facilitates better sleep later in life. I'd never made that connection before.
Stephan, is avoiding blue light in the evening for increased melatonin and all or nothing thing, or just avoinding it most of the time is good? I can't change all the lights in the house and the glasses are expensive and not subtle.
@foodrenegade, eyesight and maybe many other functions can also be affected.
*an all or nthing thing
Hi Stephan! The last comment I made began with a question of body composition method used in the study? It's normal to loose some lean mass on energy restriction due to smaller glycogen reserves in liver and muscles. Besides there is a general tendency to hold on to more water in general on diets with higher energy levels. I find it somewhat unlikely at a normal person would loose a significant amount of organs (besides fatty tissue off course!) or muscle on a 2 week modest energy restriction. James Krieger have by the way pointed out in his blog that pretty much all commonly used methods of body composition are more or less inaccurate, including DEXA scans!
I think the sleep duration is highly over rated these days..maybe it is required due to hectic lives people have these days. I know tons of people who sleep for no more than 3-5 hours everyday and are >80 years old and most importantly all are healthy ! One of them is 97 years old and he has never slept for more than 4 hours in his entire life. His diet consists of couscous, lamb (occasionally), raw milk and cheese period!
P.S The only thing worth noting is that these people are highly spiritual. They fast every other day.
So, did they do any resistance training? Rumours has it that's an effective way of not losing any LBM whilst on CR...
what was the original body fat % of the dieters in this study? if it was over 20% (which i assume would be common for overweight people) then those in the low-sleep group would be actually getting FATTER (ie body fat % increasing) on the calorie restrction diet, since the proportion of fat lost (20% of total weight loss) was less than their original body fat %. in other words, they lost a disproportionately low amount of fat, and high amount of lean mass, resulting in them getting fatter (%wise)
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The nasal strips are so important; a certain percentage of sleep apneas come from the nose, I'm 115# and 5'4" and I had sleep apnea, I was waking up gasping and my heart pounding, and it would take an hour to get back to normal, it was scary, and it was all from the nasal passages. The strips made my life so much better. The only thing is they're hard on the bridge of the nose.
And my fasting AM blood sugar is better with adequate sleep.
And, yes, Riceball, if I don't get to sleep before 11pm, I might as well stay up all night. That's what it feels like.
And thanks,Stephan,for my all-time favorite health blog, actually, for my all-time favorite blog, period.
Recently I visit your blog.
You have great work on health.
keep up the creative work.
I would like to hear more from you.
World Health Update
Thanks to Andreas for his mention of James Krieger, who has very enlightening things to say about body fat "measurement". Here are links:
Body fat measurement is NOT a measurement
Here is his bottom line: "In my opinion, often the best thing to do is not worry about a specific body fat % number, but rather look at things such as waist circumference and other circumference measurements. If they’re going down, you’re losing fat. Skinfolds are also good for seeing reductions over time (but don’t worry about translating the skinfolds into specific body fat % numbers)."
NB: One confusing factor in his presentation is he consistently says "per cent" when he means "percentage point". A 5% error on a "real" FM of 20% would mean a reading between 19% and 21%, which would be fine for most purposes. A 5 %-point error, which is what he means when he says "5% error", would mean a reading between 15% and 25%, which would be quite useless.
James Krieger is part of the dieting industry. He is NOT an obesity expert. He is a major cherry picker with an agenda.
Look toward what Dr. Jeffrey Friedman and Dr. Linda Bacon have to say.
My blog discredits James Krieger. To him, the truth is simple and certain. When in reality it is extremely complex and uncertain.
The TRUTH is we are still figuring out this obesity thing. We do not know ANYWHERE near enough about the regulation of fat cells.
Good , unbiased sound science will NOT be found on James Kriger et al's blogs. The diet industry ( which he is a part of) exists precariously on false promises and false assumptions.
Please take a look at my obesity blog and you will see how Krier, McDonald et al are wrong and spread obesity myths.
Obesity has been with us since AT LEAST 23,000 B.C. The genetic component is greater than that of heart disease or breast cancer.
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