Sunday, October 30, 2016

Green Tea Extract Reduces the Amount of Insulin You Need to Store Your PWO Carbs by ~20% + Discussed: What are the Potential Benefits During Bulking and Cutting?

The beneficial effects of green tea won't occur if you just put some GTE into your post-workout shake... well, at least they didn't occur in response to acute supplementation in the study at hand, where 3x350mg/d consumed for 7 days before a std. exercise + oral glucose tolerance test did the insulin lowering trick.
While green tea has a record of promoting the metabolic and overall health of the obese and sick, its benefits in healthy individuals are still an object of ongoing research. Research such as the latest study from the McMaster University, in which Brian J. Martin et al. (2016) evaluated the effect of supplementation with green tea extract (GTE) on the plasma glucose kinetics of eleven healthy, sedentary men (21±2 y; BMI=23±4 kg/m², VO2peak=38±7 ml/kg/min; mean±SD).

Now, this alone would probably not be SuppVersity newsworthy, but unlike other studies that assessed the effects of GTE on glucose management, Martin's study tested the effects specifically during the post-workout window - a fact that makes the study particularly interesting for SuppVersity readers.
Another important determinant of your 24h insulin levels is your meal frequency:

Grazin' Bad For the Obese!

Largest Meal For Lunch = Winner!?

Regularity is Key to Leanness

Optimal Meal Freq. 4 Kids?

8 Meals = Stable, But High Insulin

Are 6 Meals Better Than 2?
In contrast to what the study's title, "Green tea extract does not affect exogenous glucose appearance but reduces insulinemia with glucose ingestion in exercise recovery", suggests, we are not talking about an acute response study, here.

Simply adding some green tea extract to your PWO drink, alone, is thus unlikely to produce the same results. Rather than that you'd  better mirror the study protocol by consuming 350 mg of a standardized green tea extract thrice daily. After 7 days, which was the timespan after which Martin et al. conducted their oral glucose tolerance test, you should then be able to stash away a significantly larger amount of glucose with a given insulin load than before.
Figure 1: Post-workout glucose kinematics in response to a beverage containing 75g of glucose after 7 days of thrice daily green tea extract supplementation at a dosage of 3x350 mg (Martin. 2016).
As you can see in Figure 1 the chronic intake of GTE decreased the amount of insulin that was required to stash away the 75g of glucose the subjects consumed after participating in a graded exercise test (=cycling to exhaustion at ever-increasing intensities) was reduced by a statistically significant and practically relevant ~20%.
Why did GTE not improve the glucose AUC and the rates of glucose appearance and disappearance? Even though the experiment was not designed to elucidate this hypothesis, it is very likely that the lack of decreases of the amount of glucose in the blood, as well as its absorption kinetics, is probably the logical consequence of the fact that the uptake and storage already took place at the maximal physiological pace - though at sign. lower insulin levels w/ GTE.
Even though neither the glucose AUC, i.e. the amount of glucose that appeared in the blood, nor the glucose rate of appearance and disappearance decreased / increased significantly, said reduction in insulin is a clear indicator of a significantly improved insulin sensitivity - and that during a time-window where your cells' ability to take up and store glucose is already especially high, anyway.
Figure 2: Insulin is the most potent anabolic hormone known, and promotes the synthesis and storage of carbohydrates, lipids and proteins, while inhibiting their degradation and release into the circulation. Insulin stimulates the uptake of glucose, amino acids and fatty acids into cells, and increases the expression or activity of enzymes that catalyse glycogen, lipid and protein synthesis, while inhibiting the activity or expression of those that catalyse degradation (Saltiel. 2001).
In conjunction with the likewise improved oxidation of fatty acids during the workout, said reduction in insulin requirements may be an advantage during both cutting and bulking:
  • cutting - during the former part of a "get jacked"-cycle, the reduced insulin excursions could shorten the time period during which elevated insulin levels suppress the release and oxidation of fatty acids from your fat stores while being in a caloric deficit
  • bulking - during the latter part of the cycle, a reduced level of insulin could reduce the risk of fat storage while being in a caloric surplus
Eventually, it is important to note the italicization of "could" in the previously outlined hypotheses. Until their accuracy will have been proven in future studies, you better don't overestimate the results you may see from taking GTE supplements. Insulin is, after all, not half as obesogenic as Gary Taubes and co would have it... speaking of insulin: you probably don't have to be afraid to miss out on its beneficial effects on satiety and its ability to inhibit skeletal muscle protein breakdown - if the glucose AUC didn't change, it is after all very unlikely that the efficacy of insulin on other target organs wasn't increased to a similar degree so that you will experience the same satiety improving anti-catabolic effects with 20% less insulin; and yes, this means that, eventually, you could also experience the same degree of fat storage (luckily, though, PWO lipogenesis is → ZERO, anyway).
It may sound boring, but the classic combination of GTE and caffeine is probably the best fat burner left on the OTC supplement market | more
Bottom line: While future studies are, as so often, highly warranted, the study at hand provides initial evidence of the potential usefulness of green tea supplements in people who exercise regularly.

Whether the potential benefits, i.e. increased fat loss during cuts and decreased fat storage during bulks will actually occur in the everyday practice of athletic training and bodybuilding, however, is something that needs further research - research of which I'd hope that the guys at the McMaster University conduct it in the not all-too-distant future. After all, most of you will probably be more interested in the real world results than the mechanism of which Martin et al. write in the conclusion of the study at hand that it warrants further study | Comment on Facebook!
  • Martin, B.J. et al. "Green tea extract does not affect exogenous glucose appearance but reduces insulinemia with glucose ingestion in exercise recovery." Journal of Applied Physiology Published ahead of print on October 7, 2016 - DOI: 10.1152/japplphysiol.00657.2016
  • Saltiel, Alan R., and C. Ronald Kahn. "Insulin signalling and the regulation of glucose and lipid metabolism." Nature 414.6865 (2001): 799-806.