How to Weigh a Human
I’ve been dieting lately, which means that I am weighing myself pretty regularly now. I try to weigh myself every day. Because I’m trying to be so consistent, and I don’t have some kind of fancy scale, just this cheapo scale, I’ve had some troubles over the years getting a consistent read out of my scale. I’ve finally got it working about as best as I can expect out of what I have, so I thought I would write down the tricks that I use to get as consistent as possible.
One thing that I have gleaned from my job working with electronic components and also looking at some hobby robotics and destroying my old scale to see how it worked was how the new scales that are cheap and completely electronic work. The scale itself doesn’t have any springs in it at all, just a circuit board with some wires leading out to four sensors, which are attached directly to the feet of the scale. Many times you can see that the feet aren’t actually touching the bottom plastic piece of the scale - that’s because they need to be attached to the sensor plate. The body of the sensor is attached to the bottom of the scale. From there, the body is attached to the rest of the scale so that when you step on the scale from the top, the entire body of the scale is pushed down and the feet are effectively pushed into their sensors, giving a sensor reading.
The sensors are calibrated to give a reading which you can then use a simple lookup table in a microprocessor to see what it is supposed to represent in pounds. Of course there are four feet, so that means that they’re not exactly on, but the scale manufacturer assumes that there is about one fourth of your weight distributed on each one of the sensors. This brings us to tip number one, the most important:
Stand as close to the center of the scale as possible
This means that your weight will be distributed so as to make the assumptions of the manufacturer as correct as possible. Using this first rule, you will get as an accurate a weight every time you step on the scale. If you have to move the scale to the center of the room in order to stand on the center and not tilt yourself, do so. There’s a tip later if you have to move the scale every time.
Of course, that’s not the whole story, because you want to have a consistent weighing over multiple days. That means that you need to take into account three more things. The first is that more than half of you is water. This means that the amount of water that you drank in the last 24 hours and how hydrated you are right at the moment that you weigh is going to make a big difference. If you’re a heavy person like I am, just two percent of your body weight is easily 5 pounds. The second is more obvious than the first, and that is that you will gain a different amount of weight throughout each day based on what you eat and drink versus your elimination. That means that weighing at the end of the day is completely useless. The third is even more obvious: your clothes weigh different amount every day. These three facts bring us to tip number two:
Weigh yourself at the beginning of the day, naked.
Weighing yourself at the beginning of the day in the buff will give you the most consistent reading day-over-day that you can get. This is because after a night’s sleep, you are about as dehydrated as you’re going to get in the day. That minimizes the impact of the body water that you have around. It also means that you probably have digested most of your food from the previous day, and you don’t have clothes tying you down.
The third tip that I use is one that is mental. Many of the dieters that I have conversed with (hi /r/loseit!) have a problem mentally with getting on the scale every day. Getting on the scale every day is very important to me in order to keep the accurate graphs that accompany my reports. To get all of that data, I keep a logbook right next to my scale, and I put my weight in it.
It’s a simple book with the date, and the weight that I read off of the scale on that day. Even though it just looks like a weight log, it also doubles as a motivational tool! Because this type of logging lets me see all of the numbers very quickly, it’s easy enough to look back a month (it’s just one row over) and see my progress every day. The number that’s important to me is the number of a month ago minus today, and it’s always in the negative. I’ve never been on the right track and had that number come out positive. Over a longer period of time, all the variability of the last few days goes away.
Finally I have one final tip, which might not apply to everyone. I don’t have space in my apartment bathroom to keep the scale on the floor all the time, so I keep it on it’s side under the sink. This means that the zero calibration of the sensors will be off the first time I step on it every morning. The solution is simple, and applies if you have to move the scale every day as well.
Place the scale on the floor in the same position every time.
Ignore the first reading that you get - keep stepping on and off until you get two readings exactly the same
If you can’t get the same reading from two weighings just seconds apart, your scale is broken. Get a new cheap one and use these tips to weigh yourself consistently.
Following these tips, I’ve never had a problem with the 30 dollar scale that I use every day to measure my weight.