Reliable way to determine number of calories needed
I am trying to figure out if I am taking in enough calories to support my current level of activity. I'm a 56-year-old woman and not overweight. I ride 4-5 days/week, sometimes with high intensity. Saturday rides are long (40, 50, 60) with a brunch/lunch stop in the middle. I always eat sometime immediately after the ride. If anything I might eat too little, but I strive to eat the right balance of carbs/protein.
I watch what I eat and choose nutrient-dense foods for all my meals and snacks. I avoid sugar except during/after rides and on special occasions. I eat breakfast, snack, lunch, snack, dinner, and rarely anything after dinner unless I feel hungry. Since I am not trying to lose weight (nor need to), I take hunger to mean that I need to eat, especially given the intensity/duration of some of my rides.
I'm wondering if there's an accurate formula to determine how many calories I should consume each day. I found the standard BMR formula, then multiplied by .5 for my activity level; the result is 3619 calories per day! I know I don't consume anywhere near that.... probably between 2000-2400 on most days (more if we stop for brunch/lunch during long rides).
After the most strenuous rides, I feel tired that evening but I'm like new the next morning; however, my quads take longer to recover and I'm wondering if I should take in more calories/day, add more protein/carbs all day, or what. I want a reliable method and perhaps a sample eating plan showing what that number of calories looks like spread throughout the day.
Can anyone point me to a reliable resource (book, link, or other)?
Specialized Roubaix Expert
Surly Long Haul Trucker