The Science of Weighing Yourself

Recently, I was called a "dork" for using Excel to chart the progress of my weight loss. I offer no excuse. I am a dork. The question is why aren't you?

For most of us, especially the ladies in the audience, a successful week could mean losing the smallest fraction of a pound. I've had many weeks where I've only lost or gained 0.2 pounds. To put that into perspective, that's about 3/4 of a stick of butter, by weight. It doesn't seem like much, but 0.2 pounds a week can add up to serious weight loss over the long haul.

As part of my formal education in engineering, I learned to set up experiments to gather data. The key to most experiments lies in 2 factors: accuracy and precision. I won’t bore you with a thesis on engineering, but accuracy reflects how close the measurement is to the true value, and precision reflects how consistently you measure the value between tests. The dartboard analogy is often quoted in engineering school. The key for us is to precisely measure these changes to determine if your diet and lifestyle are working.

What we're looking for is our instantaneous weight (our weight at the time of measure) to be as consistent as possible. Our true weight, the weight of our body minus clothing, food and other artificial sources, is nearly impossible to measure. It’s not important, anyway. Most people don’t understand that in weight loss you don’t care how much you really weigh. Measuring your weight is only an indicator of how well you’re losing weight, not how healthy you are. If your actual weight is 150, but your measurements always says 151, who cares?

Several factors affect your instantaneous weight. They include:

• Time of day
• Food and drink consumed
• Weight of clothing being worn
• Exercise
• Day of the week.
• Quality of your measuring device

I've found that as I go through the day I gain weight. This makes sense, since I eat and drink throughout the day. The period when you sleep is the longest time most people go without food or drink in a normal day. So it makes sense that an 8-12 hour "fast" would make sure most of your food is out of your system. As a corollary, not getting enough sleep monkeys with your body's system and may affect instantaneous weight (as well as true weight, but that's another post)

If I eat a huge meal the night before I weigh in, I'll show a temporary increase in weight. Why? Because of the simple fact that that bolus of food has to work it’s way through my body. Think of it like a giant snake eating a rabbit. That snake's instantaneous weight won't stabilize until the lump passes from the head to the tail (great analogy, no?).

Weight of clothing has quite a substantial effect on your instantaneous weight. Jeans weigh a lot more than workout shorts, and heavy wool sweaters weigh a lot more than t-shirts. Some Weight Watchers I know bring their "uniform" to the meetings and change in the bathroom before weighing in.

In my experience, if I get a ton of exercise before I weigh in, I’ll show a slight drop. Your results may vary.

Common sense dictates that if you weigh in on Friday, you’ll be more consistent than if you weigh in on Monday. This is because most of us have a pretty regular routine throughout the week. I know my weekends can vary wildly with respect to food consumption, sleep and exercise.

Don’t weigh yourself on crappy scales! A scale is a precision device. The scales at my Weight Watchers center are calibrated often to ensure the absolute in accuracy. If you have the means, this is the best way. A close second is to use a doctor’s beam-type scale. These are supremely accurate, if you know how to use them. When I have the room one day, I plan on getting one.

The last unmentioned factor, uh, “un-evacuated waste”, is obvious. In weighing in as in road trips, pee before you go.

So this all adds up to our ideal weight measurement picture: Weigh in naked first thing Friday morning, before breakfast, on a good scale. Don’t eat a huge dinner the night before, and be sure to relieve yourself prior to stepping on.

Obviously, I don’t weigh in naked at Weight Watchers. Often times other things may get in the way of my perfect scenario. Here’s what I do.

I weigh in at the 12:30 meeting on Sunday. This is the time that I can attend, so I have to work around it. I wear almost the same outfit every week. Twice a year, I adjust the outfit to switch from jeans to shorts and vice versa. I don’t eat breakfast or drink more than a little bit of water before I go.

I can’t stress how much all this makes a difference. A few years ago I started going to meetings Tuesday night. My weight varied wildly from week to week because if I had a huge lunch, I’d see a swing. If I had 6 glasses of water at work instead of 10, I’d see a huge drop. All this inconsistency never let me know how I was doing, and I started to blame myself for the results. If I lost 2 pounds, I’d rejoice. If I gained 4, I’d nearly be in tears. It wasn’t until I focused more on precisely measuring my weight that I broke the cycle of joy and depression and broke through my weight plateu.