From TMAG...........
While there were several interesting topics presented, including a lecture given by a MD/PhD and research superstar Wim Saris who confirmed all of my incessant ramblings about the value of protein and amino acids with glucose and maltodextrin in a post-workout drink, the topic I found most interesting was the research presented on caffeine/coffee and insulin sensitivity.
For a while now I've been cautioning my clients and T-mag readers about the ill effects caffeine and typical thermogenic agents have on insulin sensitivity. Well, at the University of Guelph they've been investigating this issue intensively and here's what they found:
1) Caffeine intake (in all of its forms) decreases whole body glucose disposal (carbohydrate uptake) by 15-30%.
2) Caffeine intake decreases skeletal muscle glucose disposal by 50%.
3) When consumed with a standard carbohydrate breakfast, caffeine decreases insulin sensitivity, leading to large increases in blood insulin. But even in the face of this insulin surge, blood glucose doesn't disappear at a normal rate. When the body can't take up carbohydrates properly (as when drinking coffee), it releases loads of insulin to help out. However, the coffee actually prevents the insulin from doing this job and you end up with high insulin and glucose. That, my friends, is the serum profile of the obese, type II diabetic.
4) Caffeine decreases insulin sensitivity for at least three hours (this is the duration of the longest study they've performed), but the true duration of the effect isn't known. I speculate that it's at least five hours, the half life of caffeine.
In this case, many people are probably walking around all day with impaired insulin sensitivity. If you're a coffee drinker you should realize that you're living your life like a diabetic except during the times that it could actually be diagnosed. When you go to the doc to see why you're so fat or you feel like crap (if you have any glucose or insulin tolerance problems), what do you have to do? You have to fast overnight and avoid coffee! So 99% of your waking life you're functionally diabetic and that 1% of the time when it really matters and can be diagnosed, you're not. No wonder experts suggest that 50% of North Americans are diabetics who aren't diagnosed as such.
5) In one study, four groups were used to evaluate the effect of caffeine and glycemic index on insulin sensitivity.
• The first group got decaf and a low-GI breakfast. They saw a normal blood glucose and insulin response.
• The second group got decaf and a high-GI breakfast. They saw a bigger insulin and glucose response in the blood.
• However, when the low GI group got regular coffee with breakfast, their blood profile was worse than that of those who got the high-glycemic breakfast and decaf. Therefore coffee/caffeine can turn a low glycemic meal into a high glycemic meal!
• Finally, the group that drank coffee and had the high-glycemic meal ended up looking like diabetics.
6) One interesting hypothesis generated at the seminar was as follows: In terms of insulin sensitivity, caffeine alone is worse than coffee and obviously (as seen above) coffee is worse than nothing. However, some people believe that certain substances in coffee (specific quinides) can actually increase glucose disposal and improve insulin sensitivity. While the quinide content of coffee isn't strong enough to counter the effects of the caffeine, the quinides in decaf coffee may actually increase glucose and insulin tolerance. This hypothesis still needs to be tested and proper doses have yet to be discussed; however, keep your eyes out for this research in the near future.
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.
