Originally Posted by Az B
Az <-- Eatin' carbs and losin' weight.
Yeah, I wonder how much weight Mike's lost this past year on his low-carb diet? I've gone from 245lbs to 180lbs since 1-jan-05 with a diet of 60-80% carbs depending upon whether I eat 3000 to 5000 calories a day (I pretty much hold fats & protein constant and raise carbs to match activity level). That's still 500-calories/day lower than my energy expenditures from biking so I lost about 1-lb/week.
Here's a chart on the relative rates of carb vs. fat metabolism based upon exercise intensity:
from Journal Applied Physiology -
Determinants of fat oxidation during exercise
As you can see, maximum fat-usage % occurs at about 45-49%. However, to train your body to become more efficient at burning large amounts of fat%, you need to raise your VO2-max and increase your muscular efficiency (type-I fibres) through LSD training at around 10% to 5% below LT.
Originally Posted by unsuspended
Is it possible to train your body to become less affected by bonking?
You never want to get to the point of bonking, it does you no good. Your body will start taking apart perfeclty good muscle to burn for energy and you'll be undoing weeks of training. Fat-metabolism can only occur when you have sufficient carbs to start the lipid-conversion for energy.
While it's possible to burn off 1000-calories of fat while riding at 45% of VO2-max, it'll take you 3-4 hours of riding. Instead, if you focus on training and increasing your fitness (intervals, tempo & LSD workouts), you'll raise your VO2-max, increase the muscle-efficiency and eventually you'll be able to turn off 1000-calories of fat at a 60% pace instead and do that ride faster and in less time (2-3 hours). The goal really should be to increase fitness and condition, rather than just losing fat or weight.
Originally Posted by Machka
As for what to consume, you don't have to eat sugary stuff. In fact, I would stay away from a lot of sugary stuff because sugar causes your blood sugar level to spike, but the sugar doesn't sustain the spike, and your blood sugar level ends up dropping very quickly, sometimes lower than it was before you ate something. Instead, I would suggest consuming complex carbs (low glycemic index stuff), as well as some protein and fat.
Doesn't this only occur when you eat while sedentary, like sitting on the couch watching TV? Due to the rate of glucose/glycogen consumption on a ride, like 500-600 cal/hr, there's no way you can keep up with that from eating and digesting food (200-250 cal/hr). So your blood-glucose level never rises during a ride, no matter how much you eat.
Insulin levels never actually rise during exercise to cause a rapid drop in blood-glucose. If anything, that would be a
good thing since that blood-glucose is actually being transferred into the muscle-cells to rebuild the glycogen supply. This is what happens after a recovery meal, but not during the ride itself.