Yesterday I talked about understanding the output side of the calories out > calories in equation. We went through Sparkpeople's method of calculating my daily caloric needs based on BMR and activity level.
Now, let's talk about losing weight. In it's simplest form, one pound of weight equals 3500 calories. So, burn 3500 more calories that you eat, and in theory you lose a pound. Want to lose a pound a week? Eat 500 fewer calories than you burn each day. Want to lose a pound a month? Eat 120 fewer calories than you burn each day. We now have what we need to figure out how to lose the excess that we are targeting!
Let's do this old school. First off, we'll use my data. My BMR is 1950 calories. Adjust that for a sedentary lifestyle (basically sit in my office) - puts my daily base calorie needs at 2200 per day. Now, we need to adjust for exercise. I run a little over 35 miles per week. Estimating 100 calories per mile (or 3 miles per donut), I burn around 3500 calories per week. Add about 500 more cross training, and I get 4000 per week exercising. So - the equation looks like this:
Total calories out = (2200 cals/day X 7 days/wk) + 4000 = 19400 cals/wk
So, to maintain my current weight at my current activity level, I would need to eat around 2777 calories a day.
Now, I've targeted losing 15 pounds over the next six months. Assuming that six months is 180 days:
Daily calorie deficit = (15 lbs X 3500 cals/lb)/180 days = 333 cals/day
So, to lose 15 pounds at my current weight and activity level I would subtract 333 calories a day from the 2800 calories above, and I arrive at 2444 calories per day. Pretty close to Sparkpeople's calculations:
Now it's a matter of being religious and tracking the food that you are eating.
Sounds pretty simple huh? Well, let's talk about the reality of the situation. First off - all of these number are estimates. They are calculations over a population. They are not exact for Glenn Jones. Second, note the italicized letters. These calculations assume maintaining my 4000 per week calorie burn and my current weight. These are important points - as my weight decreases, my BMR will decrease. Likewise, if I reduce my weekly exercise level, then I need to adjust my exercise numbers accordingly. These two reasons are most often why we start losing weight aggressively only to plateau. More on that tomorrow.
Yesterday I did put in my miles. 9 miles in a *slow* 10:01 pace. Average heart rate was 79% of max. I'm really tired. I'm not fueling properly. Time to start eating right again.