The only reason I know this stuff is because I had an intense interest in exercise-physiology during the 10-years I was racing and emphasized that during my microbiology major. Going to med-school just didn't have the appeal of bike-racing, so I stayed with that after school.
Originally Posted by BasicJim
For the slow kids in class (me), can you recommend a "for dummies" kinda book on cycling nutrition? I have read 'Serious Cycling' and didn't feel it goes as in depth as this post does. I am looking for something to help me understand all this better.
Recommended reading?
Hmm, I'm not sure if there's a "for dummies" book on cycling physiology. I'm not even sure knowing this stuff in such detail really helps. I think it's more efficient as far as fitness-improvement vs. time ratio to just follow "do this" and "do that" guidelines when it comes to nutrition. Some good info in:
"High Tech Cycling" - Ed Burke, PhD
"Cycling Science" magazine - Chester Kyle, PhD
"Bike Tech" newsletters - Ed Burke, PhD
"Bicycling Science" - David Wilson
But if you must really know the detailed "whys" and "hows" of this stuff, you're really going to have to consult the medical journals like JAMA or NEJM. Some other studies:
Regulation of Carb & Fat Metabolism During & After Exercise
JournalAppliedPhysiology-Effect of fat adaptation and carbohydrate restoration on metabolism
JournalPhysiology-Skeletal muscle fat and carbohydrate metabolism during recovery from glycogen-depleting exercise in humans
AmericanJournalPhysiology-Postexercise fat intake repletes intramyocellular lipids but no faster in trained than in sedentary subjects
JournalAppliedPhysiology-Effect of alcohol intake on muscle glycogen storage after prolonged exercise <-- important for drunks like me
Citations in bibliographies provides further reference.
"Fat conversion is the slowest and about the fastest you can do is about 1000cal/day without tearing apart muscle at the same time
me: ah hah. is this at all related to that recommendation of not aiming higher than 2 pounds/week weight loss, or am i being simplistic?"
Yup that's correct. Conversion of stored fats to replenish energy stores actually do not go any faster in fit athletes than couch-potatoes, so you can't push this process too quickly. What happens when you try to lose weight too quickly is that you end up tearing apart perfectly good muscle; effectively negating any strengthening & fitness-increasing benefits of exercise. This occurs if you exercise a lot and do not eat afterwards. With a large calorie-deficits, you end up tearing apart muscle to make up the difference between the maximum fat-conversion calories and the insufficient amount of carbs supplied. You will may end up burning off 1000cal/day of fats, but you also take apart 250gm of muscle as well. So 1/2 of the weight loss is fat and the other 1/2 is muscle. The result is you end up getting weaker and weaker with weight loss and you end up with a skinny twig with a double-chin and body-fat percentage remains the same at 20-25%.
The other issue with large calorie deficits is that a lot of people do this through cutting calories from their intake. Malnutrition really does become a concern. You end up with mineral deficiencies leading to susceptibility to illnesses, continual fatigue and low motivation. Cutting out too many carbs also results in ketoacidosis, basically you're burning up your muscles and poisoning yourself from the inside.
The only way I've been able to get rapid weight-loss is to build muscle at the same time. So in the winter, I'll build up lots of muscle-strength through weight-training in the gym. I'll also ride lots of ong miles in early spring as well. This ends up taking apart some of the muscle I built up along with losing fat gained over the holidays.