Saturday, April 7, 2012

The Leptin-Ilex!? Does Yerba Mate (Ilex Paraguariensis) Restore Leptin Sensitivity or Does it "Just" Help You Lose Body Fat by Curbing Your Appetite?

Image 1: Mate tea, which is made of the dried leaves and twigs of Ilex paraguariensis, a shrub or small tree native to subtropical South America, has long been touted as a useful weight loss tool (img Ilosuna, Wikipedia)
Isn't it funny, how complicated losing weight has become? I mean, only 20 years ago the one thing you had to do, to lose weight was eat less and (optionally) exercise more. These days, a calorie is not a calorie anymore, the bad fats are good, the good carbs are bad and still neither of those are created equal. And as if watching your blood lipids and glucose levels was not enough, you also have to keep an eye on your leptin levels, these days. In this utter confusion the main message of a study Young-Rye Kang and his colleagues recently published in the Journal of Laboratory Animal Science appears far too simple to be true (Kang. 2012): Fat rodents who reduce their calorie intake back to normal lose all their superfluous body fat within 4 weeks. That this happened as a result of yerba mate supplementation and despite ad-libitum access to the same high fat diet (60% fat) on which they had gained all the body fat, is yet startling.

Yerba Mate yet another super tea!?

If you take a closer look at the literature the purported (and mostly experimentally verified) health effect of Ilex paraguariensis are about as numerous as the purported (and mostly unverified) "weight loss secrets" you read about all over the web, these day:
    Figure 1: Main organic components of Ilex paraguariensis extract (Bracesco. 2011)
  • mild CNS stimulant
  • potent antioxidant activity
  • anti-inflammatory effects
  • inhibition of atherosclerosis
  • management of obesity
  • vasodilation
  • lipid reduction
  • anti-mutagenic effects
  • anti-glycation effects
  • increases AMPK activity*
    *click here to read all about AMPK
As the data in figure 1 goes to show there are a whole host of bioactive components in Yerba Mate, of which caffeine and the other methylxanthines account for the immediate, stimulating effects, while the polyphenols, which are more abundant in Mate than in green tea (Bracesco. 2011), are at the heart of its anti-inflammatory, anti-obesity and anti-hyperlipidemic effects.

Fat, appetite or leptin reduction - which comes first?

In view of this extensive list of health benefits, it should not surprise you that the recently published study by Kang et al. is not the first to report potential weight loss effects of mate tea or respective extracts. In fact, people have been guzzling mate for quite some time now, and I have read numerous reports of how a few cups of mate tea per day helped people stick to their diet.
Figure 2: Food intake (in kcal, left) and body weight (relative to control, right) of obese (HFD) and normal weight (normal) mice after 4 weeks on normal or 60% fat diet (data adapted from Kang. 2012)
Now, you could certainly argue that it was just the increased fluid intake that filled those people up, so that they ate less and thusly lost weight. And in fact, a cursory glance at the data in figure 2 would support this hypothesis, if the obese C57BL/6J mice, who received 0.5g/kg, 1.0g/kg and 2.0g/kg of 5/1 mate extract via intragastric gavage (for a human being this would equal ~2g, 5g or 10g of capped mate extract per day), had not consumed slightly less fluid than their peers in the HFD or normal control group.
Figure 3: Organ and fat weight (relative to non-obese mice in control group) after 4 weeks of HFD + 0.5, 1.0 or 2.0g/kg mate extract (data calculated based on Kang. 2012)
Against that background and in view of the restorative (not destructive) effect the addition of the Ilex paraguariensis extract had on the organ weights of the animals (cf. figure 3, left), it appears unlikely that the profound reduction in calorie intake in the middle and high dose groups was a response to either the satiating effect of increased fluid intake, or potential toxic effects and subsequent anorexia.
Figure 4: Adipocyte size, leptin and blood glucose levels (relative to normal-weight control on std. diet) after 4 weeks of HFD + 0.5, 1.0 or 2.0g/kg mate extract (data calculated based on Kang. 2012)
Rather than that, the reduction in circulating leptin levels, which went hand in hand with reduced adipocyte sizes and plasma glucose levels in the treatment groups receiving 1.0g/kg and 2.0g/kg Ilex paraguariensis, would suggest that the weight loss effect of the mate extract was (at least partially) mediated via its restorative effects on the regulatory mechanisms by which mammals, which are profoundly disturbed by the hyperphagia-inducing effects of the "high fat" rodent diets (a better term, than "high fat" would actually be hyper-energetic - and who knows, maybe even "hyper-palatable").

Calories count, but counting does not work 

Image 2: Yerba mate won't allow you to binge all day, but it may help you to reduce the desire to do just that.
It is certainly debatable, whether or not the leptin sensitizing effect was the chicken or the egg, or in other words, whether the reduction in food intake and the subsequent loss of body fat facilitated the purported restoration of leptin sensitivity, or vice versa. From a practical point of view, this is yet about as insignificant as the "main working ingredient" in the plain water extract (200g from 1kg raw material), the scientists used. A potential candidate certainly is chlorogenic acid, of which you have read in previous posts here at the SuppVersity that is is one of the components scientists believe is responsible for the weight loss effects of coffee and coffee bean extracts. The catechins, as well as the gallic acid content probably don't hurt either.

Eventually, it does yet not really matter, because if - as I believe - the restoration of leptin to normal levels is a secondary effect of weight loss, the most important message of this study is not that drinking liters of mate tea will help you lose weight, but rather that losing weight will restore your leptin sensitivity and if that is the case, you do not even need a pill (RX or not ;-) to get back in shape.... apropos "in shape", if this is your current goal make sure to come back over the Easter holidays for the fat loss installment of the "Step By Step Guide to Your Own Workout Routine"!