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| Needless to say: The fat burning effect is not one that relates to body fat... and that a dose-escalation (4 instead of 1 cups would bring about such an effect is relatively unlikely, too). |
What is it then, if it's not coffee that bumps up the postprandial fat oxidation?
At face value, the answer seems to be straightforward; it's an old acquaintance and - at least for supplement junkies - probably the #2 on the list of "I know that stuff"-ingredients in coffee: chlorogenic acid - I've discussed its effects and how to maximize its content in coffee in all detail in my coffee buying, roasting, brewing 101 (btw. if you haven't listened to me explaining it on Ben Greenfield's podcast, do you here).
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Not as useless as raspberry ketones, but...
In spite of the fact that the previously cited study has been retracted, there's ample evidence from rodent studies, that chlorogenic acids (CGAs) reduce blood pressure and body fat, and enhance fat metabolism.
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| Table 1: The previously reported improvements in glucose and fatty acid metabolism in response to CGA were not augmented when the HHQ was removed. The set of markers the scientists tested under fasting conditions were identical. At least for triglycerides (TG) and non-esterified fatty acids (NEFA), glucose and insulin I'd yet like to see postprandial data, as well... this data is not available, though, and I am not sure if Katada et al. didn't measure or just didn't report it. |
Bummers: The scientists fail to report if their subjects were habitual coffee consumers. The scientists did not analyze (or didn't publish the data) the std. markers of glucose and fatty acid metabolism from Table 1 in the postprandial state. They were advised, though, to "avoid excessive intake of coffee other than the test beverage, foods that contain a high amount of CGA (e.g., eggplant, potatoes), and foods that contain a high amount of polyphenols" (Katada 2018).
What we do know, already, is that HHQ counteracts the antihypertensive (=blood pressure lowering effects of CGA | Yamaguchi 2008), as Katada et al. (2018) highlight in their latest paper, it is yet likely that it will also diminish CGA-induced fat oxidation (FOX). Accordingly, the scientists tested the effects of CGA-enriched and HHQ-reduced coffee on FOX in a crossover study (4-week washout) on fifteen healthy male volunteers (age: 38 ± 8 years (mean ± SD); BMI: 22.4 ± 1.5 kg/m²). The study did, however, not, as you probably expected, measure the acute response to a HHQ-reduced coffee, but had the subjects consume "the test beverage (coffee) containing the same amount of CGA with HHQ (CGA-HHQ(+) | 428 mg/128ml CGA, 570 mcg/128 ml HHQ) or without HHQ (CGA-HHQ(−) | 382 mg/128ml CGA, 80 mct/128ml HHQ - that's a relative reduction of 85%) for four weeks" (Katada 2018) - and yes, that's just one cup of coffee.So, if it works, how potent is the effect?
To get an idea of both, the effect size and the potentially underlying mechanism that would trigger the reduction in postprandial FOX the authors hypothesized they'd observe, they measured FOX, as well as the ratio of the biological antioxidant potential (BAP) to the derivatives of reactive oxygen metabolites (d-ROMs) as an indicator of oxidative stress.
Practical advice to save money: Buy lightly roasted coffee. As you've learned in the coffee buying, roasting, grinding, brewing 101 it will have naturally high CGA and naturally low HHQ levels, anyway... and let's be honest: in view of the fact that even this special coffee preparation won't burn body fat, you probably won't be missing out if skip the extra expenses | learn more
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| Figure 1: Effects of 4 weeks on "high octane" coffee (orange) vs. regular coffee (blue) on the average antioxidant status and fatty oxidation rate in the initial 300 min after a test meal in 15 male, healthy volunteers (Katada 2018). |
In that, the scientists speculate (IMHO for a good reason) that "the mechanism underlying the inhibition of FOX by HHQ is related to postprandial oxidative stress" (Katada 2018). What they don't mention explicitly is that the practical relevance of the observed effects is... well, at least questionable. As highlighted in the light-blue "practical advice"-box, it is furthermore not unlikely that you would see similar health-improving effects by simply choosing a lighter roast. After all, you've learned in the SuppVersity 101 on coffee buying, roasting, grinding, brewing that the degree of roasting is the main determinant of the CGA content of coffee - what I didn't explicitly mention in that article, though, is that darker roasts will also have increased levels of HHQ.
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| Figure 2: The one parameter that would matter when it comes to weight loss, i.e. the post-prandial increase in energy expenditure is not significantly different for the low HHQ coffee (CGA-HHQ(-)) - data based on Katada 2018. |
And while it is very difficult to quantify the long-term effects of lower post-prandial stress, it stands out of question that, in view of the role of increased oxidative stress in the development of the metabolic syndrome, the highly significant reduction of a proven and often-used indicator of oxidative stress (learn more about the BAP/d-ROMs ratio) the scientists observed after 4 weeks 'on' their "High Octance" vs. regular coffee could add to the benefits of other dietary and behavioral strategies to reduce oxidative stress and thus indeed help you prevent or even combat metabolic syndrome.
What you must not expect, though is that switching to an, as of yet unavailable, "high octane" (=HHQ reduced coffee) will get you jacked in no time. Why? Well, the increase in fat oxidation is mediocre and - as every SuppVersity reader will know: the amount of fat you burn is in no way directly related to the amount of body fat you lose - eventually it will all come back to energy in vs. energy out and that's where the study found no significant difference (see Figure 2).
Now that doesn't mean that potentially glycogen- and protein-sparing effects of an increased mobilization and oxidation of fatty acids were not conducive to weight, or I should say fat loss; weight loss wonders as in the retracted CGA study, however, cannot be expected | Comment!
- Katada, et al. "Effects of Chlorogenic Acid-Enriched and Hydroxyhydroquinone-Reduced Coffee on Postprandial Fat Oxidation and Antioxidative Capacity in Healthy Men: A Randomized, Double-Blind, Placebo-Controlled, Crossover Trial." Nutrients 2018, 10(4), 525; doi:10.3390/nu10040525.
- Yamaguchi, Tohru, et al. "Hydroxyhydroquinone-free coffee: a double-blind, randomized controlled dose–response study of blood pressure." Nutrition, Metabolism and Cardiovascular Diseases 18.6 (2008): 408-414.