Intra-workout Carbs, Caffeine, & Insulin Resistance

pbandy1

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Like many of you, I'm a big fan of peri-workout carbs, particularly highly branched cyclic dextrins. However, after researching some pre-workouts that contain caffeine, I was surprised to see that caffeine in physiological amounts is a pretty big inducer of insulin resistance.

Obviously this can't be a good thing during a workout. Intra-workout carbs will spike insulin which is good for transporting glucose+aminos to where they need to go, yet caffeine seems to cause a reduction in insulin-mediated glucose uptake (likely due to increasing epinephrine).

Am I missing something here?

I can share some studies with you guys but I don't think this is new to anyone here.
 

rhoadx

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I really don't have anything to back this up but I've thought about a similar situation. My thoughts are that the caffeine will lower whole body insulin sensitivity ( both muscle and fat) but resistance training will increase insulin sensitivity in muscle only. Therefore making a more favorable situation for glucose uptake in muscle. This is only me thinking out loud, I have not researched into this much, but it's a thought. I'm interested in others opinions on this
 
kbayne

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Like many of you, I'm a big fan of peri-workout carbs, particularly highly branched cyclic dextrins. However, after researching some pre-workouts that contain caffeine, I was surprised to see that caffeine in physiological amounts is a pretty big inducer of insulin resistance.

Obviously this can't be a good thing during a workout. Intra-workout carbs will spike insulin which is good for transporting glucose+aminos to where they need to go, yet caffeine seems to cause a reduction in insulin-mediated glucose uptake (likely due to increasing epinephrine).

Am I missing something here?

I can share some studies with you guys but I don't think this is new to anyone here.
I wouldn't be too worried about caffeine having a negative impact on insulin sensitivity. Caffeine at mega doses can lower insulin sensitivity, only for a very short period, very negligible though. With the exception of doses as high as 400-800mg, caffeine really has no impact on blood glucose or insulin levels.
 
Jiigzz

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Like many of you, I'm a big fan of peri-workout carbs, particularly highly branched cyclic dextrins. However, after researching some pre-workouts that contain caffeine, I was surprised to see that caffeine in physiological amounts is a pretty big inducer of insulin resistance.

Obviously this can't be a good thing during a workout. Intra-workout carbs will spike insulin which is good for transporting glucose+aminos to where they need to go, yet caffeine seems to cause a reduction in insulin-mediated glucose uptake (likely due to increasing epinephrine).

Am I missing something here?

I can share some studies with you guys but I don't think this is new to anyone here.
Exercise itself blunts insulin response intra. You use other mechanisms to shuttle carbs during a workout
 

kdubson14

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Uptake of glucose is not insulin dependent during exercise
 

pbandy1

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I wouldn't be too worried about caffeine having a negative impact on insulin sensitivity. Caffeine at mega doses can lower insulin sensitivity, only for a very short period, very negligible though. With the exception of doses as high as 400-800mg, caffeine really has no impact on blood glucose or insulin levels.
I'm not so sure that insulin sensitivity is reduced for a short time though. The study below suggests that 200 mg caffeine taken twice a day (400 mg total, as you stated) in 16 healthy people can cause insulin resistance for up to 12 hours after administration.

Metabolic and hormonal effects of caffeine: randomized, double-blind, placebo-controlled crossover trial.

^ can't post links yet
 

pbandy1

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Uptake of glucose is not insulin dependent during exercise
Right, so exercise has the benefit of non-insulin mediated glucose uptake. I believe this is because exercise essentially causes Glut4 translocation which allows glucose to be shuttled where it needs to go. But isn't insulin-mediated glucose uptake still important as well?

Secondly, caffeine decreased Glut4 expression according to the study below (in rats, granted). A decrease in Glut4 is never a good thing, correct?

Acute vs chronic caffeine: Are the effects on insulin sensitivity mediated by altered insulin/AMPK signaling pathway?
 
muscleupcrohn

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I'd say that the benefits of caffeine (power output and/or energy to have a good workout, or even workout at all) far outweigh any potential negative effects that it would have on insulin resistance (with regards to progress in strength and/or body composition). There are plenty of people (just about everyone) who takes caffeine of some sort pre-workout on a regular basis and make incredible progress and gains.

OP, are you just wondering about this for the sake of curiosity/knowledge, or are you actually concerned that having caffeine pre-workout is going to have some sort of detrimental effect on your progress?
 

pbandy1

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I'd say that the benefits of caffeine (power output and/or energy to have a good workout, or even workout at all) far outweigh any potential negative effects that it would have on insulin resistance (with regards to progress in strength and/or body composition). There are plenty of people (just about everyone) who takes caffeine of some sort pre-workout on a regular basis and make incredible progress and gains.

OP, are you just wondering about this for the sake of curiosity/knowledge, or are you actually concerned that having caffeine pre-workout is going to have some sort of detrimental effect on your progress?
Well right now I am just taking coffee pre, but I am concerned that if I take some type of preworkout that it could affect glucose levels negatively. I was overweight as a kid and have pretty bad genes in the fat /insulin department.
 
The_Old_Guy

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My uneducated guess would be that if you undertake regular resistance/cardio training and have a solid handle on how many kcals you need to cut/maintain/clean bulk... worrying about Caffeine intake in the 200-400mg range PrWO, is not worth your time. Heck, just have your carbs 90 minutes PrWO - they'll still be in you, "doing their thing" during your lifting session :D
 
muscleupcrohn

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My uneducated guess would be that if you undertake regular resistance/cardio training and have a solid handle on how many kcals you need to cut/maintain/clean bulk... worrying about Caffeine intake in the 200-400mg range PrWO, is not worth your time. Heck, just have your carbs 90 minutes PrWO - they'll still be in you, "doing their thing" during your lifting session :D
This. Lots of people rely on caffeine (and other stimulants) pre-workout and throughout the day while cutting. I just can't see the caffeine being something worth worrying about in reality. There are other factors that will play a much more significant role in weight gain/loss.
 

kdubson14

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I'm not so sure that insulin sensitivity is reduced for a short time though. The study below suggests that 200 mg caffeine taken twice a day (400 mg total, as you stated) in 16 healthy people can cause insulin resistance for up to 12 hours after administration.

Metabolic and hormonal effects of caffeine: randomized, double-blind, placebo-controlled crossover trial.

^ can't post links yet
Baseline HOMA%S was not measured but this study recorded a 35% decline in insulin sensitivity.

Study design:

We conducted a double-blind, placebo-controlled, randomized crossover trial among healthy, nonsmoking, nonpregnant students 18 years or older. To ensure that subjects could comfortably complete the study, we required each participant to have a history of tolerance to caffeinated beverages or antifatigue caffeine tablets and no history of cardiac arrhythmia or seizures. Subjects were recruited from the student body at Dartmouth College through e-mail announcements and posters. Each subject signed an informed consent document, which was approved together with the protocol by the Institutional Review Board at Dartmouth-Hitchcock Medical Center. Consenting participants were randomized to one of two sequences: placebo followed by caffeine or caffeine followed by placebo. The randomization list was completed using a random number generator. The active agent phase of each sequence consisted of taking a 200-mg tablet of caffeine twice (total of 400 mg) daily for 7 days. The placebo phase consisted of taking an identical placebo on the same schedule. All participants made 5 visits. At the first visit (day −5), eligibility was confirmed, participants gave informed consent, and baseline caffeine intake was assessed using a questionnaire. Subjects were asked to abstain from all products containing caffeine for the subsequent 5 days. A list of caffeine-containing products was provided to aid in this effort. At visit 2 (day 0), after the 5-day washout, patients were randomized to one of the two sequences. They were given a 7-day supply of study capsules and instructed to take one capsule twice daily—one between 8:00 and 10:00 AM and one between 4:00 and 6:00 PM. They were again instructed to refrain from caffeine-containing products and were asked to return 7 days later in the morning after an overnight fast. At visit 3 (between 8:00 and 9:00 AM of day 7), participants had blood drawn for measurement of study end points and were instructed to return 5 days later while abstaining from all caffeine-containing products. At visit 4 (day 11), after the second washout period, patients were entered on another 7-day study period, conducted as in the first. This was completed at visit 5, when patients returned between 8:00 and 9:00 AM on day 18 for phlebotomy

Right, so exercise has the benefit of non-insulin mediated glucose uptake. I believe this is because exercise essentially causes Glut4 translocation which allows glucose to be shuttled where it needs to go. But isn't insulin-mediated glucose uptake still important as well?

Secondly, caffeine decreased Glut4 expression according to the study below (in rats, granted). A decrease in Glut4 is never a good thing, correct?

Acute vs chronic caffeine: Are the effects on insulin sensitivity mediated by altered insulin/AMPK signaling pathway?
Acute caffeine administration at levels relevant in humans (3-4 cups per day) decreases GLUT4 protein expression by ~30% in rat skeletal muscle. This is mediated through adenosine receptors. No affect on AMPK. Caffeine also increases phosphorylation of IRS-1 at Ser residues.

Effect in human is dependent on baseline insulin sensitivity. Caffeine restores insulin sensitivity to normal levels in the obese via reduction of plasma NEFA levels. Glucose uptake reduced by ~25% in "lean" (BMI < 25) men post light exercise (walking). Meta-analyses indicate 20-30% reduction in insulin sensitivity and glucose uptake at rest in the "lean." I don't think I've seen anything done with resistance training

Resistance training increases GLUT4 expression 60-100% post-exercise, returning to baseline ~24 hours later. Long-term trained individuals express up to ~200% GLUT4 mRNA content at baseline vs untrained or detrained while GLUT4 protein content increases 400% despite mRNA levels returning to baseline between exercise bouts.

Typed this up from old notes, I can post references when I have more time if interested
 
toddmuelheim

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SO NOW WHAT DO I DO
 
muscleupcrohn

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Intra-workout Carbs, Caffeine, &amp; Insulin Resistance

SO NOW WHAT DO I DO
If you feel you need some energy pre-workout, take some caffeine.

Guys, I love doing research and optimizing training and supplements, but let's be real here.
 

pbandy1

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If you feel you need some energy pre-workout, take some caffeine.
basically this.

I will also share one more study.

Caffeine ingestion decreases glucose disposal during a hyperinsulinemic-euglycemic clamp in sedentary humans. (2001)

This study essentially showed that caffeine reduced glucose disposal by 24% and carbohydrate storage by 23% at rest. So I would argue that it is dependent in how you personally deal with glucose disposal and insulin resistance. For me, I have a fat boy background and have **** genes when it comes to eating carbs / gaining fat / insulin sensitivity. But if you are an already lean individual and perhaps don't struggle with carbs like others, it likely won't make a huge difference.
 
muscleupcrohn

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basically this.

I will also share one more study.

Caffeine ingestion decreases glucose disposal during a hyperinsulinemic-euglycemic clamp in sedentary humans. (2001)

This study essentially showed that caffeine reduced glucose disposal by 24% and carbohydrate storage by 23% at rest. So I would argue that it is dependent in how you personally deal with glucose disposal and insulin resistance. For me, I have a fat boy background and have **** genes when it comes to eating carbs / gaining fat / insulin sensitivity. But if you are an already lean individual and perhaps don't struggle with carbs like others, it likely won't make a huge difference.
I wouldn't advise that people avoid pre-workout caffeine be use they have "bad genes" regarding carbs and gaining fat. Hell, caffeine is in a ton of fat burners that work, and caffeine has even been part of stacks/combinations that have shown significant weight loss in studies. Caffeine can also improve workout quality by increasing energy, and also has been shown to increase power output. Look at the big picture here guys...
 
kbayne

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As stated before, the pros trounce all over the cons.
 

kdubson14

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Seriously, caffeine is pretty much magic. Though I personally haven't used any pre-workout in months because of 2x EC earlier during the day.

You wanna talk about insulin sensitivity? EC WRECKS insulin sensitivity.
 

pbandy1

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Seriously, caffeine is pretty much magic. Though I personally haven't used any pre-workout in months because of 2x EC earlier during the day.

You wanna talk about insulin sensitivity? EC WRECKS insulin sensitivity.
EC? ephedrine?
 
Jiigzz

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basically this.

I will also share one more study.

Caffeine ingestion decreases glucose disposal during a hyperinsulinemic-euglycemic clamp in sedentary humans. (2001)

This study essentially showed that caffeine reduced glucose disposal by 24% and carbohydrate storage by 23% at rest. So I would argue that it is dependent in how you personally deal with glucose disposal and insulin resistance. For me, I have a fat boy background and have **** genes when it comes to eating carbs / gaining fat / insulin sensitivity. But if you are an already lean individual and perhaps don't struggle with carbs like others, it likely won't make a huge difference.
Please be careful trying to extrapolate data from special populations to healthy humans.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1464218/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2277186/

I think the forest is being missed for the trees here. Does any of this really even matter?
 
muscleupcrohn

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Please be careful trying to extrapolate data from special populations to healthy humans.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1464218/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2277186/

I think the forest is being missed for the trees here. Does any of this really even matter?
Both of these, especially the latter in this case. What is the practical relevance of this for members of this forum? Are people really worried that that taking some caffeine pre-workout is going to ruin their insulin sensitivity to the point that it will have a negative effect on their body composition? Really? Besides having the potential to help with weight loss, especially when combined with other ingredients, caffeine gives you energy for better workouts, and acutely improves power output. I love scientific debate and talking studies as much as the next guy, probably more actually, but come on here, haha.
 

kdubson14

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In for more info on this
I was being hyperbolic.

E itself is hyperglycemic and insulinogenic. Combined with C, there is a non-significant increase in glucose and insulin levels.

http://onlinelibrary.wiley.com/doi/10.1016/j.clpt.2003.11.375/abstract


HOMA-IR increased by 0.65 above baseline 60 min after EC ingestion. Squares = EC, triangles = E, circles = caffeine



HOMA-IR = glucose(mg/dL) * insulin / 405

Both of these, especially the latter in this case. What is the practical relevance of this for members of this forum? Are people really worried that that taking some caffeine pre-workout is going to ruin their insulin sensitivity to the point that it will have a negative effect on their body composition? Really? Besides having the potential to help with weight loss, especially when combined with other ingredients, caffeine gives you energy for better workouts, and acutely improves power output. I love scientific debate and talking studies as much as the next guy, probably more actually, but come on here, haha.
Don't worry about it
 
john.patterson

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I was being hyperbolic.

E itself is hyperglycemic and insulinogenic. Combined with C, there is a non-significant increase in glucose and insulin levels.
Interesting info, thanks for the study dude!
 
Jiigzz

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Both of these, especially the latter in this case. What is the practical relevance of this for members of this forum? Are people really worried that that taking some caffeine pre-workout is going to ruin their insulin sensitivity to the point that it will have a negative effect on their body composition? Really? Besides having the potential to help with weight loss, especially when combined with other ingredients, caffeine gives you energy for better workouts, and acutely improves power output. I love scientific debate and talking studies as much as the next guy, probably more actually, but come on here, haha.
That was the point of my ending statement, lol.
 

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