Originally Posted by
chet31
^ No, I'm not incorrect, but you are not incorrect either. I agree you burn fat while riding, but then why is every serious cyclist not at 0% bodyfat? The OP wants to lose weight. He must run a caloric deficit each day, and his glycogen reserves are not going to be "topped off" for his work-outs. You are a fit athlete, and whether intentionally or not, you are riding with strong glycogen reserves. You indicate you ride faster with a few days rest - you are allowing your liver and muscle glycogen reserves to build. The OP will not have this luxury and is going to have to flirt with bonking each work-out. I personally see nothing wrong with this. Losing weight and peak athletic performance do not go hand in hand. I would prefer the OP consider doing several rides during the week of moderate intensity versus trying to do a once/week high intensity ride. However, if he insists on losing weight and doing the killer ride once/week, his only hope is to do some kind of carbo loading the day or two before his ride - in which case neither his weight loss nor his ride will be ideal.
Our endocrine system tries to control our body fat percentage. There are feedback loops between various hormones and body fat. This explains why it is increasingly difficult to get fat off as fat stores decrease, and why there are levels of body fat below which it is unadvisable to remain for long periods.
It is unnecessary for glycogen stores to be "topped off" for workouts. Between muscle and liver we store about 2000 calories of glycogen. A cyclist may burn an average of between 500 and 700 calories per hour on a hard ride, depending on talent and training. Some of this will come from feeding, some from fat, some from glycogen, the percentages depending on intensity. The average person is going to have a really hard time burning off that 2000 calories before exhaustion. It's relatively easy to prevent glycogen depletion by eating on long rides and cyclists can put back the glycogen they burn with a simple regimen of recovery drink, snacks, and dinner, which is not the same as putting back all the fat they burn. I do intentionally ride and train with good levels of glycogen.
Much more important, and the controlling factor in the riding mix, is hormone depletion rather than glycogen depletion. I need rest before long or competitive rides to restore hormone balance. Younger riders need much less of that than older riders like me.
Controlled studies show that maximum lipid oxidation occurs at a level between 65% and 75% of VO2max, higher levels being shown in elite cyclists. Since most of us have no way of measuring oxygen uptake while riding, 65% of VO2max approximately correlates to a heart rate (HR) of 78% of max HR.
More information on fat burning, HR, and VO2max here:
http://www.betterhealth.vic.gov.au/b..._hormones?open
http://www.abcbodybuilding.com/cardiolayman.pdf
http://www.brianmac.co.uk/vo2max.htm
http://www.brianmac.co.uk/maxhr.htm