Wednesday, August 1, 2012

Does Your Diet Fail, Because You Sleep Too Little? 40 Min Extra Sleep Will Shed 1 Exta Pound of Fat in 6 Months

Image 1: Blindfolds are cheaper than light-tight curtains or shutters and they are more versatile ;-)
I have repeatedly emphasized the importance of quality sleep, here at the SuppVersity. Based on my own experience sleeping should be your your #1 priority if you want to look good, feel good and perform at your personal best on the cognitive and physiological level into your old age. Unfortunately, the number of controlled long(er)-term studies on the issue is quite small and the epidemiological data either unreliable, inconclusive or both (in most of the cases, the latter is the case; for a review see Nielsen. 2011). I was therefore happy to see that the results of one of the comparatively tightly controlled study from the Healthy Active Living and Obesity Research Group at the Children’s Hospital of Eastern Ontario Research Institute in Canada confirm my personal experience - even if the effect-size was not as pronounced as I would have expected. But let's take one thing after the other...

Take 123 overweight men and women and reduce their caloric intake by 600-700kcal ... 

... what is going to happen? Well, the answer to that question should be straight forward, right? These obese men and women, whose mean age was 41.1 years and who had an average BMI of 33.2kg/m², should begin losing weight, right? According to my previous post on "Busting the 3,500kcal = 1lbs Weight Loss Myth!" not necessarily 1lbs in 5-6 days but 1lbs in say 10 days should be the minimum. So, after the 24-week study period of trial Jean-Philippe Chaput and Angelo Tremblay conducted, the 90% of the participants who reported that they actually complied to the dietary prescription should be ~16.8lbs or 8.4kg lighter.
Figure 1: Lean mass and fat mass loss over the 24-week study period (left, calculated based on data + the information that the mean ratio of lean to fat mass loss was 3:10; Chaput. 2012); illustration of what min. and maximal weight loss would mean, if the data was normally distributed (right)
In view of the fallacy of the "calories-in-vs-calories-out" hypothesis and its logical consquence, the "eat less, lose more" diet trap, it should not come as a surprise that the average weight loss across all participants fell short of the expectations. In that, it is however interesting to remark that the expected 8.4kg are identical to the mean weight loss + one standard deviation of the same; now, if we assume a normal distribution (warning: scientific jargon! see figure 1, right for some illustrations ;-) of the data, this implies that ~16% of the subjects lost even more than my conservative prediction of 8.4kg would have suggested.

Never underestimate the fat-burning prowess of a good night's sleep!

The reasons the other 84% "underperformed", however, are manifold (keep in mind: Against the background that many obese people simply get more obese year by year even stagnation may have been progress for some). Those I consider the most important / likely ones are:
Table 1 (Chaput. 2012): This is the original table from the study and while it says "baseline characteristics" it is actually no wonder that the subjects did not lose more weight if their baseline energy intake was already as low as 1,310kcal (=5242kJ/day). After all, that would be what I would suggest as a good energy deficit (~20-30%) to lose weight, already.
  • reporting to be compliant, when you actually are not - a 24h food recalls done every 2 weeks as in the study at hand are notoriously unreliable, even if subjects don't fake them intentionally.
  • eating way too little - in view of the fact that the reported baseline calorie intake was only 1,310kcal the additional reduction of 600-700kcal put them in starvation mode; no wonder they hardly lost weight (I wonder if the authors did maybe enter the reduced energy intake into the "baseline characteristics table, accidentally; cf. table 1)
  • not eating the right whole foods - people tend to think "if I go to starve I better starve on chocolate and pie than on broccoli and chicken filet", so that - in the absence of concrete meal plans - subjects would eat cream cake every day and still comply to their goal wrt to total energy intake
Non-compliance (suggested read: "High Carb vs. High Fat for Obese Type II Diabetics and What Really Happens, When Science Meets Real Life), over-dieting and food quality aside, there is a fourth factor which would have been on my list, as well, if it had not been on Chaput's and Tremblay's the research agend, anyways: SLEEP! Duration and quality.
Figure 2: Fat loss as a function of sleep duration (left) and sleep quality (middle; both based on Chaput. 2012); as well as the "normal" distribution of PSQI (sleep quality scores) among healthy people (right; from Buysse. 1998)
Interestingly enough, the total sleep duration remained a better predictor of dietary success, as defined by loss of pure body fat (r =0.26), than the actual sleep quality (r = -0.20; note: -1 or 1 would indicate perfect negative or perfect positive correlations) even after adjustment or age, sex, baseline BMI and the
change in total energy intake (r Duration = 0.34 vs. r Quality = -0.31; data not shown in figure 2). This may be surprising at first, but in view of the fact that only PSQI score greater than 5 are highly sensitive to determine whether you are or aren't a "good sleeper" it appears reasonable.

And still, my personal experience tells me that without a reasonably good sleep quality you will rather feel worse than better if you simply stayed in bed for another 83min. So my suggestion remains (see implications for more): Get yourself a blindfold and earplugs - it will make a huge change to your sleep quality and you ability to sleep longer and wake up more refreshed and don't worry about either the alarm clock or your partner. While you will hear the former anyway, your partner certainly won't mind if you are better rested and physically more attractive than ever, although that may mean that he or she will be nudging you more often to put the blindfolds to an alternative and certainly not less enjoyable use ;-)
Implications: The results of this study put another emphasis on the importance of good sleep (7-9h every night) in the context of losing weight, building a better physique and living an overall healthier and happier life. Aside from the previously mentioned ear-plugs and blindfolds, there are yet a couple of other things you can / should do to get the sleep your body needs
  • go to bed with or as closely after sundown, whenever this is possible - don't worry if you are "up early" this is how life is supposed to be, not the other way around (note: alarm clocks are 100% non-paleo ;-)
  • don't sacrifice your social life for sleep, but don't persuade yourself that you have to party everyday and thus cannot go to bed in time
  • don't use your computer / mobile phone / social media in the vicinity of going to bed; it will delay your ability to fall asleep and the light of the small (often blueish) LCD screens will interfere with your circadian rhythm
  • if anything have a shake or other readily digestible food before bed, otherwise digestion may interfere with  your sleep quality in the first 2h and losing 2 out of 8 hours of sleep could already cost you 1.4kg of body fat you would otherwise have lost (you know the figure is mere statistical shenanigan, right?)
  • plan your TV consumption and set a deadline for when the boob tube must be off; even consider buying a timer switch to make sure it will be off
  • consider using melatonin and light therapy for a short period of time (or strategically, when you are a shift worker) to get into the new rhythm (dosing 3-10 mg melatonin before bed, 15-45min bright light therapy when you wake up or strategically during night shifts; eg. Sharkey. 2001; Bjorvatn. 2007; Sadeghniiat-Haghighi. 2008)
There will be way more on this in the future, as I am - as some of the SuppVersity Facebook friends know - still working on a post / series of posts on the circadian rhythm and a couple of past experiences of my own - including the use of light therapy to tweak my biorhythm. For the time being I suggest that you go to the official PSQI website, download the test (click on "PSQI instrument"), fill out and evaluate the questionnaire, take the first 5 steps I have outlined above, and see if that's not already enough to get an even better night's sleep in the next two weeks to come. And just in case that's not enough or your partner has gotten so fond of the blindfolds that there simply is too little time left for sleeping during the night hours, you will soon find more information on the 6th bullet point and the whole theoretical background of circadian rhythmicity and how it can work for, but also against your... until then, good night!

  • Bjorvatn B, Stangenes K, Oyane N, Forberg K, Lowden A, Holsten F, Akerstedt T. Randomized placebo-controlled field study of the effects of bright light and melatonin in adaptation to night work. Scand J Work Environ Health. 2007 Jun;33(3):204-14. 
  • Buysse DJ, Reynolds CF 3rd, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res. 1989 May;28(2):193-213.
  • Chaput JP, Tremblay A. Sleeping Habits Predict the Magnitude of Fat Loss in Adults Exposed to Moderate Caloric Restriction. Obes Facts 2012;5:561–566.
  • Nielsen LS, Danielsen KV, Sørensen TI: Short sleep duration as a possible cause of obesity: critical analysis of the epidemiological evidence. Obes Rev 2011; 12: 78–92.
  • Sadeghniiat-Haghighi K, Aminian O, Pouryaghoub G, Yazdi Z. Efficacy and hypnotic effects of melatonin in shift-work nurses: double-blind, placebo-controlled crossover trial. J Circadian Rhythms. 2008 Oct 29;6:10.
  • Sharkey KM, Fogg LF, Eastman CI. Effects of melatonin administration on daytime sleep after simulated night shift work. J Sleep Res. 2001 Sep;10(3):181-92.