Check out the book called “Racing Weight” by Matt Fitzgerald.
If you want to break down your calories, it’s relatively easy. Determine your BMR (basal metabolic rate) = how many calories you burn at rest, no activity. Then, adjust for your daily, normal activity level (not counting training) and add x 1.10 (not active) x 1.15 (medium) or x 1.2 (very, such as a personal trainer or someone who stays on his or her feet all day). Google BMR (not BMI) and you’ll find calculators online that will get you in your general range.
Once you have that figure (BMR + adjusted for activity level), then wear a heart rate monitor to gauge your calorie burn in various trainings that you do. Use one that measures heart rate (and lets you set in your own personal age, weight, etc. settings - such as a Polar…not all Garmins calculate calories as accurately, depends on the model).
An alternative is to get your BMR actually tested, which would also account for your body fat percentage.
Once you have your daily BMR, adjusted for normal activity, and then factor in your calorie burn for your training – then you can do the math.
One pound = 3,500 calories
How much weight do you need to lose? If you lose it too fast, you will lose lean mass, and this is NOT good. It’s easier to lose a pound of fat than to add a pound of lean mass. SO, that’s really the last thing you want to do. UNLESS you are super bulky, and mass outside of certain ranges does not benefit endurance athletes as much. This is personal, body type, and “Racing Weight” I think touches on this.
The overall percentage of fat you are trying to lose will help guide you on how many pounds per week, for example, it may be wise to target.
Studies consistently show that people almost always UNDERreport their calories. The only way to run the numbers is to keep a food journal. Just because you consume X number of calories per day and another guy your general height burns X number is not a great way to reach your racing weight goals in the most efficient way.
Also, appetite will not be the best indicator. Once you know how many calories to target, given all these factors, then eating very healthy and wisely choosing nutritious foods that make you feel more full will help regulate your appetite. Having said that, if your aim is to lose weight, you can expect some measure of hunger to be normal. You just need to be sure you are not either depriving yourself or eating too much and be sure you are making smart food choices for optimal performance.