A DISTURBING study on Caffeine

[Hacker]

Post by retropump

This is from retropump on AF:



1) "Caffeine intake (in all of its forms) decreases whole body glucose disposal (carbohydrate uptake) by 15-30%."

This statement should be qualified with "possibly in adult males" since caffeine has no effect on glucose disposal in females (Metabolism 2000 Jan;49(1):101-7; Influence of age on the thermic response to caffeine in women.)

2) "Caffeine intake decreases skeletal muscle glucose disposal by 50%"

This statement should be qualified by "in sedentary couch potatoes" since this is clearly not the case during exercise (J Physiol 2000 Dec 15;529 Pt 3:837-47; Caffeine ingestion does not alter carbohydrate or fat metabolism in human skeletal muscle during exercise).

"So the final word on coffee and caffeine is this - stay the heck away from it! The only way to minimize the damage it causes may be to drink your coffee with a very low carbohydrate meal and eat only low carb meals for the next few hours after your coffee intake. I know, I know, it now sucks to be a coffee drinker! But giving up your java may bring you some great health and physique benefits"

This is a bizarre conclusion to come to for a website that promotes itself as being into fitness, and also until very recently sold a thermogenic stack which included caffeine. There is a plethora of research that shows that caffeine and even more so caffeine plus ephedrine leads to an increase in energy expenditure, better exercise tolerance (via glucose sparing effects) and an increase in lipolysis that leads to a significant fat loss. As one paper summarized

"Twenty-four-hour energy expenditure was higher in both groups during drug treatment. Ephedrine+Caffeine did not produce systematic changes in glucoregulatory variables, whereas plasma leptin concentrations decreased in both groups with drug treatment. Overall, these results show that E+C treatment can promote fat loss through an increase in energy expenditure, or in some individuals, a combination of an increase in energy expenditure and a decrease in food intake."

"The thermic effect of caffeinated and decaffeinated coffee ingested with a standard breakfast was studied in 8 healthy subjects with indirect calorimetry. A higher increase in the metabolic rate was observed after ingestion of the breakfast with coffee containing caffeine than after that with coffee deprived of caffeine."

Although I agree that excess caffeine consumption in combo with a meal high in carbs may not be a good idea if you're obese or already insulin resistant, I firmly believe that some java first thing in the morning (before cardio or weights) or before any exercise is a good thing. And ECA clearly helps people lose fat no matter when it's taken. Even when consumed with a carb meal, I think of coffee as being two steps forward and one step back. In other words you still make progress, though obviously you would make more progress if you left out the carbs. To me this argues strongly to reduce carb intake rather than caffeine!!!

 

[beefybull]

(but i still drink diet cokes! lol anyone know how much caffeine is in those buggers compared to a glass of coffee?)

-= nav =-

45.6mg per 12oz can

 

[beefybull]

Here's a site that lists caffiene content of many pops:

http://www.straylight.org/dave/caffeine/beverage.html

 

[PANTS]

Does this theory apply to tea as well.
Tea, with its lower caffeine levels, surely would not have such a detrimental effect. Or would it?

 

[nandi12]

This statement should be qualified by "in sedentary couch potatoes" since this is clearly not the case during exercise (J Physiol 2000 Dec 15;529 Pt 3:837-47; Caffeine ingestion does not alter carbohydrate or fat metabolism in human skeletal muscle during exercise).

It's probably better to say the results of the research are equivocal. That study you cited showed that:

" Arterial lactate and glucose concentrations were increased (P< or =0.05) by caffeine"

So caffeine and exercise together still result in elevated plasma glucose. The authors conclude that:

"These findings indicate that caffeine ingestion stimulated the sympathetic nervous system but did not alter the carbohydrate or fat metabolism in the monitored leg. Other tissues must have been involved in the changes in circulating potassium, fatty acids, glucose and lactate"

A more recent study came to a different conclusion, namely that caffeine does inhibit glucose uptake and glycogen synthesis in skeletal muscle during exercise, but exercise reduces the effect of caffeine.

These studies looked at caffeine DURING exercise. They did not conclude that a trained person suffered less effect from caffeine on glucose disposal while at rest. So it's not quite correct to say that caffeine impairs glucose disposal only in couch potatoes.

Diabetes 2002 Mar;51(3):583-90 Related Articles, Books, LinkOut


Caffeine-induced impairment of insulin action but not insulin signaling in human skeletal muscle is reduced by exercise.

Thong FS, Derave W, Kiens B, Graham TE, Urso B, Wojtaszewski JF, Hansen BF, Richter EA.

Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Canada. [email protected]

We investigated the effects of caffeine ingestion on skeletal muscle glucose uptake, glycogen synthase (GS) activity, and insulin signaling intermediates during a 100-min euglycemic-hyperinsulinemic (100 microU/ml) clamp. On two occasions, seven men performed 1-h one-legged knee extensor exercise at 3 h before the clamp. Caffeine (5 mg/kg) or placebo was administered in a randomized, double-blind fashion 1 h before the clamp. During the clamp, whole-body glucose disposal was reduced (P < 0.05) in caffeine (37.5 +/- 3.1 micromol x min(-1) x kg(-1)) vs. placebo (54.1 +/- 2.9 micromol x min(-1) x kg(-1)). In accordance, the total area under the curve over 100 min (AUC(0--100 min)) for insulin-stimulated glucose uptake in caffeine was reduced (P < 0.05) by approximately 50% in rested and exercised muscle. Caffeine also reduced (P < 0.05) GS activity before and during insulin infusion in both legs. Exercise increased insulin sensitivity of leg glucose uptake in both caffeine and placebo. Insulin increased insulin receptor tyrosine kinase (IRTK), insulin receptor substrate 1-associated phosphatidylinositol (PI) 3-kinase activities, and Ser(473) phosphorylation of protein kinase B (PKB)/Akt significantly but similarly in rested and exercised legs. Furthermore, insulin significantly decreased glycogen synthase kinase-3alpha (GSK-3alpha) activity equally in both legs. Caffeine did not alter insulin signaling in either leg. Plasma epinephrine and muscle cAMP concentrations were increased in caffeine. We conclude that 1) caffeine impairs insulin-stimulated glucose uptake and GS activity in rested and exercised human skeletal muscle; 2) caffeine-induced impairment of insulin-stimulated muscle glucose uptake and downregulation of GS activity are not accompanied by alterations in IRTK, PI 3-kinase, PKB/Akt, or GSK-3alpha but may be associated with increases in epinephrine and intramuscular cAMP concentrations; and 3) exercise reduces the detrimental effects of caffeine on insulin action in muscl

 

[PANTS]

Does this apply to tea (black) or even green tea?

 

[nandi12]

Green tea has actually been a popular and somewhat effective herbal way to LOWER blood glucose in asian countries for quite a while. Here is a recent abstract:

J Biol Chem 2002 Jul 12; [epub ahead of print] Related Articles, Books, LinkOut


Epigallocatechin gallate, a constituent of green tea, represses hepatic glucose production.

Waltner-Law ME, Wang XL, Law BK, Hall RK, Nawano M, Granner DK.

Department of Molecular Physiology and Biophsyics, Vanderbilt University Medical Center, Nashville, TN 37232-0615.

Herbs have been used for medicinal purposes, including the treatment of diabetes, for centuries. Plants containing flavonoids are used to treat diabetes in Indian medicine and the green tea flavonoid, epigallocatechin gallate (EGCG), is reported to have glucoselowering effects in animals. We show here that the regulation of hepatic glucose production is decreased by EGCG. Futhermore, like insulin, EGCG increases tyrosine phosphorylation of the insulin receptor and IRS-1 and it reduces PEPCK gene expression in a PI3K-dependent manner. EGCG also mimics insulin by increasing PI3K, MAPK and p70s6k activity. EGCG differs from insulin, however, in that it affects several insulinactivated kinases with slower kinetics. Furthermore, EGCG regulates genes that encode gluconeogenic enzymes and protein tyrosine phosphorylation by modulating the redox state of the cell. These results demonstrate that changes in the redox state may have beneficial effects for the treatment of diabetes and suggest a potential role for EGCG, or derivatives, as an anti-diabetic agent.

 

[pittbull2]

Now I'm glad that I never got into coffee , but i do drink a glass of tea now and then.

 

[nandi12]

Yeah, people who are only mildly insulin resistant and don't have type 2 diabetes could probably save a bundle of money and drink green tea instead of ALA.

 

[tprop]

Here's my understanding on caffeine. Caffeine mimics insulin, so even if your blood sugar is high your insulin level will be low. This will cause blood sugar (not insulin) levels to be high. As long as the blood glucose is properly disposed of (ALA will help this) then the sugar will not enter the cellular level causing stored energy, aka fat. Check out Animalbolics Diet. He has a good grasp on insulin. A few small meals composed of Protein, some complex carbs or fruit (apple) and a caffinated beverage early in the day to keep insulin down. Then carb and protein load after workout to boost insulin to send that protein to repair muscle. Also, insulin sensitivity is only decreased by the body constantly having to process simple sugars. I may not be completely right, but that's my understanding from lots of study on the topic.