Moving targets: predicting weight loss by calories burned

As I mentioned the other day, last week I lost three pounds.  Since I’ve been obsessionally faithful in logging nearly every morsel into my CalorieKing software, I can report that I ate an average of 250 calories a day LESS than the software recommended.  Here’s the way that worked (warning: math follows):

• On a day when I would have no exercise, the software recommends that I should eat about 1850 calories in order to lose about a pound a week.  What I actually at on average, then, would have been about 1600 calories a day (assuming no exercise).
• On days when I did exercise (which happened to be every day last week, though the Sunday workout was just a half-hour stroll through the woods), I entered the exercise done and the time I spent on it, and the software provided an estimated amount of calories burned in the workout. (I average about 650 calories per workout, combining weights and elliptical.)  In those cases, the software ADDS those calories back to my 1850 cal allowance for the day.  So instead of an 1850 cal limit, I actually am able to eat an additional 650 calories on days I work out, for a total of 2500 calories.

In short, last week I averaged 2500-250, or 2250 calories eaten per day.  Which, given my exercise, was enough to lose three pounds.

Now, here’s the problem with this data:  It doesn’t really account for the amount of weight lost very well. Why?  Well, let’s do the math (okay, more math):

Psych of weigh-in day and the “cat drop metric”

Today is “weigh-in day” and so there is some need for psychology.  So just a word on how that tends to go.

Many folks working on weight loss are familiar with the basics here:

1. Your weight fluctuates — it can actually bounce around as much as five or so pounds from day to day.  So the usual advice is: don’t weigh yourself all the time and get highly reactive to the results, because it’s easy to get discouraged if, say, you weigh the same or even more today than yesterday.  (Especially if you’ve worked your buns off and missed a favorite dessert last night in hopes of a big change today.) (Also, don’t weigh yourself on Monday morning, unless you spend weekends at Camp Lejune or in a monastery living on broth.)

2. If you’re doing a lot of exercise, you’ll probably be adding muscle, and muscle weighs lots more than fat.  So while you’re actually losing fat and replacing it with muscle, which is a much more efficient tissue for weight maintenance (muscle needs more energy to live; fat is basically storage and hardly needs any), you may be disappointed by the scale’s results.

This is all state of the art science and also common sense.  Still… it’s kind of disappointing, isn’t it?  Because for those of us who are chronically tormented by our weight, we still would feel better if the scale said “LESS!!!” every day.