O.K first i'm sorry if this has been discused, but I couldn't find anything that really answered my questions. I have a polar heart rate monitor and it shows how many calories i burned throughout a workout. Obviously the only info it is using to determine how many calories i've burned is my heart rate. Is this acurate? Are there more factors than just my heart rate? Also, I know that your calorie intake should be about the same as the calories burned each day to stay at your current weight. But what if I burn say 3500 calories on a day that has a good amount of workouts in it, but on a day when I only do a relaxing ride, I burn like 2000 for the day. Does that mean my caloric intake should be closer to the high or the low, or somewhere in the middle? From what I hear, I shouldn't skimp on eating on rest days, so i take that as meaning i should have about the same caloric intake on all days regardless of the workout. Is this right at all? By the way, I am about 5,7 and about 130lbs in the morning, without clothes on, before eating or drinking anything. Is this good at all for the shorter side of endurance cycling? sorry for all these questions in the same loooooong thread, but they all kind of tie into the same overall thing. Any way, I am obviously kinda new to serious cycling, so thanks a bunch for any help with any of this.