Weighing and Measuring

Weighing and Measuring 

Thursday, August 11, 2011 

Measurement is the fundamental problem of managing diet and exercise for weight loss. We all know that if we expend more calories than we take in, over time we should lose weight. The problem is that there isn't an easy, accurate way to measure either side of the equation. 

For most of us, measuring calories expended is a lost cause. We don't know what our basal metabolism burns for sure, and we have no good way to quantify exercise in excess of basal metabolism. The SP fitness tracker is nice for motivating me to keep doing stuff, but I have no confidence in the calories burned numbers it generates. Bicycling at 13 mph is not any harder for me than walking at 4.2 mph, and in fact is a bit easier. But the fitness tracker gives me an awful lot more calories for the biking than the walking. I have no idea whether the biking is overstated, the walking understated, a bit of both, or they're both off by different amounts in the same direction. And there are no calories added for lifting weights. I know I'm buring a lot more calories doing 3 sets of 8 deadlifts at 185 lbs than I am walking down the street for the time it takes me to do those three sets. 

So how do people know how many calories they're burning? Typically, by seeing how many calories they're consuming and whether this is producing a weight gain or loss. Measuring calories consumed is an inexact science, but at least it's better than measuring calories expended. 

I came across an interesting video about losing weight the other day. Superficially, this is a plug for weighing instead of measuring volume. It seems a bit overblown to me, probably because the real purpose is to sell books from the web site mentioned late in the video. But I do see an element of truth in the video, even if I draw a different lesson from those facts than the folks who made it. 

For those of you who didn't want to go watch the video, or quit in disgust at the overdramatic style, the premise is that the average dieter understates what she eats by using generous volume measurement, and the conclusion is that this is a reason diets can fail. The secondary conclusion is that this can be corrected by using weight measurement instead of volume measurement. 

I look at the same facts, assuming they are actually facts, a bit differently. I see the problem as one of system and attitude. The systemic problem is a diet that says you must eat X servings of defined size. The attitude problem is following the diet but cheating on the serving size, whether consciously or not.

Fortunately, the SP nutrition tracker lets me set up a different system to accommodate a different attitude. The attitude is that I want to accurately record what I eat, and I don't want to be forced into predetermined serving sizes. The system is, if I use foods that are defined as grams or ounces or cups instead of servings, I can measure what I eat and put the real measurement in, then the computer will figure out the nutrition values and tell me what I used and what I have left for the day. 

 It's true that the scale is more accurate than volume measurement, particularly for foods that can be of varying density. A week or so ago, I bought some pre-made salad at Walmart. I found that someone had already put in the nutrition information; but they had recorded the serving size as 3 cups. I put the same information in for myself and recorded the serving size as 85 grams. Why? I don't want to eat 3 cups of salad. I want to pour how much looks right into my bowl and know what I have. That's a lot easier with a food scale than with a measuring cup. 

And the scale is an awful lot more accurate than estimating, for example, a medium potato. I buy russet potatoes. The SP guidelines for small, medium and large russet potatoes tell me diameter in inches. My potatoes aren't even close to being spherical and come in more than three or four different sizes. Fortunately, red potatoes are measured in grams. I think I'm closer to the real value by calling 186 grams of russet potato the same amount of red potato than I would be trying to guess whether the potato was small or medium. 

So I kind of come to the same solution as the video, even if I think the video is overdramatic. I like weighing for the accuracy.  I've come to like grams better than ounces, because the margin of error is smaller. The margin of error when I weigh in grams is so small that it doesn't matter. 

There are still some things I measure by volume, including oatmeal. Why? Because I've been making oatmeal for years, and making it based on volume. One part oatmeal to two parts milk, and if the measuring cup is filled to the same level for the oatmeal as for the milk, it works. I'm going to do this once per day, usually 5 days per week. Oh, and my measurement is 1/3 cup, not the arbitrary 1/2 cup that is the serving size on the package of oatmeal. It's enough. 

Similarly, I'm going to fill my 8 oz. glass to a consistent level and not worry about whether it's really 8.5 oz. or 7.5 oz. The difference a half ounce of milk or orange juice makes just isn't big enough to worry about, and I'm not doing this five times a day. 

 But stuff that's hard to measure by volume - that gets weighed. It's just easier to tell how much I'm eating when I weigh it.