As we enter the lower mileage of the winter riding season, overall daily Calorie needs will go down. And failing to change our eating pattern will lead to those extra pounds that are hard to shed in the Spring.
This example (from a recent question to me) is an easy example to review how you can calculate your own daily requirements.
Q: I am trying to calculate my daily Caloric requirements. I am a 44 year old, 80 kg male and would like to calculate my Daily Caloric Requirement for a day which includes a two hour ride at 30 km/hr.
Calculating your daily caloric requirement
First you take your basic metabolic rate (BMR):
(which is for a sedentary individual)
BMR (men) in Cal/day = 10.2 times weight in kilograms + 879
You are 80 kg so BMR = 10.2 x 80 = 816 + 879 = 1695 Calories
Then you add in the Calories for digestion/absorption (10%) = 1695 + 170 = 1865 Calories to maintain an even weight.
Next, you decide on the Calories for exercise:
(many online services such as Strava will also show or estimate your caloric expenditure for a given activity)
You are riding 2 hours at 30 K/hr
I am going to cheat here and use the pre-calculated 20 miles/hr = 32 k/hr
That is 742 Cal per hour so 2 x 742 = 1484 Cal
And add 10% for the "thermic effect" of absorption = 1484 + 148 = 1632 Calories additional just for the exercise portion of the day
Your total energy needs for that day would be 1865 = 1632 = 3497 Cal
Breaking down your diet
First I take the usual basic PROTEIN needs - this is the same no matter what your level of exertion.
(Too much protein is not better or needed) so 1.2 gms protein per kg body weight x 80 kg = 96 grams of protein needed (let's round to 100 gms protein) x 4 Cal/gm = 400 Calories from protein.
Next the day's FAT requirement http://www.cptips.com/fat.htm
I err on the low side and as exercise goes up, you will add more of the excess Calories needed for the day as carbs, not fat. (Remember it is carbs that are powering the additional exercise. ) Another way to look at it would be that you take your BMR of 1865 Cal (above) and take 40% of those Calories as fat = 1865 Cal x .4 = 746 fat Calories needed / 9 Cal/gm for fat = 83 gms of fat for the basic diet.
Then you take the remaining Calories (no matter what the length of the ride and eat them as CARBOHYDRATES. So in our example 3497 total Cal needed for the day - 400 protein Calories - 746 fat Calories = 2351 Cal still to be replaced. 2351/ 4 Cal per gram for Carbs = 588 grams of carbohydrate to reach the needed Calories for the day.
Thus, for the example of a day with a 2 hour ride it would be:
100 gms PROTEIN = 400 Cal
83 gms FAT = 746 Cal
588 grams of CARBOHYDRATE = 2351 Cal
For days with a longer rides this means you will eat a lower percentage of your needs as fat (than the 40% we used for your BMR diet) and overall get closer to the 20% of total Cal number mentioned on the page about fat requirements.
Edited 2 time(s). Last edit at 12/14/2015 12:45PM by Skye.