|I suppose you will have known that sleep hygiene & green tea help, but did you know the exact numbers when it comes to their effects on your resting energy expenditure, as well? No? In this case, today's SuppVersity article is for you!|
In 2011, Christian Benedict and colleagues conducted an interesting study. The German scientists examined the resting energy expenditure of 14 normal-weight male subjects on two occasions during a regular 24-h sleep-wake cycle (including 8 h of nocturnal sleep) and a 24-h period of continuous wakefulness in a balanced cross-over study.
On the morning after regular sleep and total sleep deprivation, resting and postprandial energy expenditures were assessed by indirect calorimetry, and the free choice food intake from an opulent buffet was tested in the late afternoon at the end of the experiment.
In addition to energy expenditure and intake the scientists also checked, whether the lack of sleep would affect the concentrations of ghrelin, leptin, norepinephrine, cortisol, thyreotropin, glucose and insulin; and they did so repeatedly over the course of the whole 24 study period.
|Figure 2: 10% reduction in insulin sensitivity after less than one week of sleep deprivation is bad news, even if there were two outliers where the insulin sensitivity increased - they are the literal "exceptions that confirm the rule" (Buxton. 2010)|
Three to six cups of green tea and a good nights sleep - that's all?!
Let's leave the sleep issue now and get to #2 on today's list of RMR boosters: Green tea. There is surprisingly little evidence with respect to the beneficial or detrimental effects of green tea on sleep. What we do know, though, is that theanine, an amino acid that can be found in all sorts of teas, appears to promote healthy sleep in people who are at a particularly high risk of not getting their daily dose of quality sleep due to ADHD (Lyon. 2011) and people who have problems to relax (Mason. 2001; Unno, 2013).
Now theanine has also been found to "partially counteracts caffeine-induced sleep disturbances" (Jang. 2012). Accordingly, you may argue that it's probably not that much of a problem if you are consuming green tea relatively close to going to bed. Personally, I would yet not recommend taking the risk that the caffeine messes with your sleep (learn more).
The reason green tea made it into today's issue of the "natural metabolism boosters"-series should be obvious: There are dozens of studies showing increases in RMR, even when the guys or, as in the case of a 2010 study by Stendell-Hollis, the girls in the placebo group experienced a diet-induced reduction in resting metabolic rate.
|Figure 3: Changes in RMR in cancer survivors on lifestyle program with or without 960 mL of green tea per day with, on average, 236 mg total catechins (Stendell-Hollis. 2010)|
|Figure 4: Energy expenditure (EE) during the 125 h chamber stay plotted against the five different treatments. Inter-group differences in % (Gregersen. 2009).|
It is thus questionable, whether it makes sense to buy caffeine-free green-tea extracts, unless you want to take an additional dose right before bed and plan to combine the product with coffee or caffeine tabs in the AM and early PM.
|Figure 5: Modified overview of the changes in energy expenditure (left) and fatty acid oxidation (right) from Hursel et al. (2008) - a brief glance at the data from the circled trials indicates: there is a benefit from adding catechins!|
Toxicity Warning! Do yourself a favor and don't buy lead, chromium and cadmium laden Chinese green tea. I wrote about this problem back in May and I don't think that the levels have improved in the mean time (learn more). In the end, even the previously reported reductions in testosterone in response to green tea consumption could be related to unwanted heavy metals.
|Figure 6: Green tea does more to help you lose weight than to increase your energy expenditure (Rains. 2011)|
In conjunction with the other established benefits of green tea catechins, as they were highlighted by Rains et al. in a 2011 review (see Figure 6), the addition of green tea extracts to your regimen as a means to increase and maintain your resting energy expenditure appears warranted, specifically if you're suffering from high grade inflammation, as well.
There is yet more to the data in Figure 5, specifically to the data that relate to a study by Sonia Bérubé-Parent, Catherine Pelletier, Jean Doré and Angelo Tremblay (check out the data from the Bérubé-Parent study in isolation). Their study does after all answer the question that may be preying on your heads, now: Yes, there is an increase in energy expenditure with increasing EGCG levels, but this increase is minimal and the use of more than 250mg/day appears futile based on the data Bérubé-Parent et al. collected.
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