Daily percent change in your weight

[LOL!]

I have a nice scale by the bathtub, so it is easy to step on it and see my weight in a couple of seconds.

I've noticed that my weight can vary by 4% in a single day which is about 6 to 7 pounds for me.

I've also noticed that I lose weight sleeping because I can weigh myself just before I climb into bed and when I get up in the morning.

Most of this makes sense because all the change is from outputs (sweating [a lot when I exercise] and using the toilet) versus inputs (eating and drinking).

How about you? Do you think to yourself that your weight is the lowest of the day, the highest of the day, a specific time of the day??

 

[NW-Bound]

Recently, T-Al and CaliforniaMan brought up the problem of the bathroom scales lying, and I verified their story.

Basically, if you step on the scale twice or three times in a row, the scale remembers its last reading, and if the new reading is within x.x lbs of the last reading, it will keep showing that last reading. This gains it an air of "repeatability" and "accuracy", while it has neither. Its true repeatability may be worse than 1% or 2-3 lbs for an adult easily.

You can defeat the scale internal logic by weighting yourself, then do it again while holding an object of a known weight such as 1 gallon of water. Keep weighting yourself alternatively with and without the water, and you will see the true randomness of the scale.

My nice digital bathroom scale turned out to be a piece of lying crap!

 

[LOL!]

Yes, I noticed the "memory" of the scale and take steps to prevent that. I also calibrated the scale with weights used with a barbell which in turn were calibrated with a shipping scale at work.

I also tested the reproducibility taking into account the "memory". Thus, I believe my scale is both accurate and precise when used properly. For instance, I can drink 16 oz of water and see a 1 lb change when I weigh myself.

 

[W2R]

I can tell what my Weight Watchers weigh-in is going to be, within about 0.2 pound, if I weigh myself at home just before going there.

Yes, my weight varies by about 2% depending on a variety of things. I try to weigh myself when all of those factors are the same but that's not always possible.

Can weather make a difference? Perhaps it is my imagination, but my perception is that a lot of people seem to gain at Weight Watchers when the humidity is high before a storm. I am not sure why that would be the case.

 

[zinger1457]

Basically, if you step on the scale twice or three times in a row, the scale remembers its last reading, and if the new reading is within x.x lbs of the last reading, it will keep showing that last reading. This gains it an air of "repeatability" and "accuracy", while it has neither. Its true repeatability may be worse than 1% or 2-3 lbs for an adult easily.

I have a Soehnle digital scale that you have to tap the top with your foot to turn it on and wait for it to 0, takes ~2 seconds. When you step off the scale the display immediately shuts off and you have to start over again by tapping the top and waiting for it to 0. Didn't see the memory issue you mentioned probably because it does shut off and resets after ever weight taken, and it does seem to be very repeatable.

 

[bjorn2bwild]

My scale is the mechanical spring type - I don't think it has the brain power to lie to me. I can lose ~ 5lbs on a 1 1/2 hour run on a hot day.

 

[Animorph]

Digital scale with the button tap start-up calibration. I measure each morning at the same point in my morning routine and enter the weight into Excel.

For the past year:

Standard deviation: 1.3 lbs
Max: average + 4.2 lbs (probably skipped a few vacation days...)
Min: average - 3.2 lbs

 

[braumeister]

Digital scale with the button tap start-up calibration. I measure each morning at the same point in my morning routine

Same here. But I don't put it in a spreadsheet daily.
What I have done for many, many years is to have a sheet of paper on the bathroom counter with a grid on it. Just a blank spreadsheet page printed out, with dates across the top and weight on the Y axis.

Each morning, DW and I weigh ourselves and put a mark on the paper (each sheet covers about six weeks). We both consider the daily weight to be a fairly random number, but the trend is what we care about.

During any period when one of us experiences a rising trend, the other one teases him/her about it. Conversely, during a decreasing trend, that person gets lots of encouragement.

For long term trends, I keep a spreadsheet on the computer with our weights on the first day of every month. This goes back about 15 years now, and it's interesting to see the rising, falling, and stable trends.

 

[Walt34]

We also have a scale in the bathroom so easy to keep track. I can easily change 4 lbs in a day and have done so for years. It's not something I invest a lot of time in thinking about.

Target weight is 145. If it's above that, I eat less. If below, chocolate cake or pizza is okay.

 

[steelyman]

At home, I weigh myself daily right after morning shower (so at least it's the same time of day).

Although my objective is to gain weight (to mid-160s), I still find it useful to use a free app called LoseIt! to track and graph my weight. I don't know if it's available for non-Apple devices, but I think it's well-done and easy to use.

 

[NW-Bound]

I have a Soehnle digital scale that you have to tap the top with your foot to turn it on and wait for it to 0, takes ~2 seconds. When you step off the scale the display immediately shuts off and you have to start over again by tapping the top and waiting for it to 0. Didn't see the memory issue you mentioned probably because it does shut off and resets after ever weight taken, and it does seem to be very repeatable.

Mine functions exactly the same way, with the tap to start for zeroing, etc...

That is not sufficient for self-calibration as it would need another data point, like a 200-lb precise weight.

Yes, mine turns itself off as soon as I step off, but the doggone "memory" is still on.

As I mentioned, I did not believe T-Al and CaliforniaMan until I tested it myself, alternating the weighting with two different weights A and B. You can also alternate between DW and yourself stepping on the scale. With mine, either method exposed its lying scheme. It is not possible for a person to vary his weight by 2-3 lbs within 1 min. Try for yourself!

What T-Al did was similar, but he pressed down with only one foot as the alternate weight.

 

[NW-Bound]

OK, I just repeated the experiment.

I tapped the scale with one foot, waited for it to "zero", then stepped on. It said "A". Did it again. "A", it said. Again. "A". Again. "A".

Four consecutive identical readings in a row. To the last 0.1 lb, which is the scale resolution.

Then, I did it again, but alternating between myself, and myself holding 1 gallon of anti-freeze (it happened to be the 1st thing I found in the garage).

Instead of alternating between the same "A" and "B" precisely, its reading of "A" now fluctuated plus/minus 0.2 lbs. The same with "B", whose readings fluctuated plus/minus 0.2 lbs. Occasionally, I would get a reading that was off by 0.5 lbs, but that was one out of 7 or 8 times.

T-Al reported that he saw a scale that fluctuated 2 lbs or more. So mine is a lot better than his, but mine still uses a trick to lie.

The problem with digital scales vs. analog dial scales is that digital scales have a readout to 0.1 lb, but their internal springs and mechanical/electrical transducers have random errors higher than 0.1 lb. So, they have to cheat because people expect to see the same number to 0.1 lb when they weigh themselves repeatedly.

On a mechanical scale, squint hard as you might, you only expect to read to the nearest 1 lb. Perhaps if you look at the dial with a magnifying glass, you might see the same variation between weightings, but people are not going to do that. A digital readout just makes it more obvious.

PS. By the way, my "A" and "B" differ by about 10 lbs on the average. A gallon of water should weight 8.3 lbs, so perhaps antifreeze is heavier than water.

PPS. I do believe that people's weights fluctuate by a few pounds through the day. Why, I eat, drink, and relieve myself through the day, so why shouldn't my weight vary? I was just pointing out that a scale may add to this variation, or hide it!

 

[Katsmeow]

I am in weight loss mode so I weigh very morning after I get up. I've done this for a very long time and I have a Withings scale so it uploads my weigh ins. I also go to WW meetings every Friday and weigh right before I leave so it is very consistent with that as well.

There are many reasons for fluctuations in weight that aren't related to "true" weight gain or loss.

The main reasons for weigh fluctuations that apply to both men and women:

1. Water retention -- If you eat food with a lot of sodium, you are more likely to weigh more the next day. So, I would not go out and eat Chinese food the day before a WW weigh in unless I wanted to have a tick upward in my weight.

2. Digestion of food. One reason most people weigh their lowest in the morning is because they don't eat during the night and food is digested during the night and doesn't weigh as much.

3. Umm, how to put this. Well - bathroom issues. Most people recognize that you should weigh in the morning after you get up and go to the bathroom, rather than before. What people don't always think about are things like constipation. If the waste from the food you have digested is still in your body then you will weigh more than if you had eliminated that food from your body.

4. Exercise. The one that gets a lot of people is doing weight lifting. When you do weight lifting your body will retain more fluids. I've learned not to do strength training workouts the day before I weigh in at Weight Watchers.

 

[dallas27]

I an a former wrestler, high school coach, and "making weight" expert. Competed in the us open in 2012.

You can drop 30-40 lbs in a month, 3-5 in 30 minutes. Lose 2-4 sleeping. 1-2 spitting. 0.2 with an emergency haircut. 0.1 temporarily by doing a handstand.


Word of advice, weight doesn't matter, the mirror is 1000 times more useful in measuring health.

And never take the advice of anyone who quotes BMI.

Generally the morning is when most are lightest, hence the origin of the word breakfast. You also tend to be dehydrated then.

 

[splitwdw]

OP, Why are you weighing yourself so often? I thought if you were tracking your weight for health reasons you were suppose to weigh yourself about once a week or so.

 

[LOL!]

@splitwdw, I work out about 2 hours every day. I am trying to figure out how much I need to drink during a long run in hot weather. I suffer from cardiac drift.

 

[AllDone]

I've been doing Weight Watchers since February with an average of 0.75 lbs per week loss, but salty restaurant meals on Saturday or Sunday really show up at my Monday weigh-in, yet will be gone by Tuesday and on the following Monday, if I'm careful about salt, I'll have a spectacular loss.

Bathroom scales don't have "memory", they're just inaccurate to start with and in time the springs get worn. I recently replaced my kitchen scale since the old one had stopped registering small additions. If you added ingredients too slowly, it wouldn't register any change in weight. (A lot like me! No memory and the joints are aging!) If my bathroom scale acted like it had a "memory", I would just buy a new one.

 

[Alan]

I weigh usually myself once each day in the morning after getting up on a digital scale in our bathroom, and seeing a 1% change from 1 day to the next is fairly common.

I also still record my weight once a week, Wednesday morning, and it is usually +/- 1 or 2%.

When traveling I never weigh myself, and that can be many months at a time. Last year I weighed in on the last Wednesday in March and didn't weigh again until the first Wednesday after we got back in late September. I was very pleasantly surprised to see that my weight was exactly the same as when I left, particularly since the last 22 days of the trip was on board cruise ships.

 

[scrinch]

My scale must not have the memory feature, because I can repeatedly reweigh myself and see variations of a few 1/10ths of a pound. I can also weigh myself before and after a trip to the bathroom and see a 0.4 lb difference (200ml). I can also weigh myself before and after playing a couple hours of tennis (or in the past after an hour run) and see I've lost 10 lbs or more. Obviously I have hyperactive pores when it comes to sweating! I was paired up with my boss playing doubles last week...after a while he looked around at the water on the court and asked "Why is it raining only on our side of the court?"

 

[NW-Bound]

... I can also weigh myself before and after playing a couple hours of tennis (or in the past after an hour run) and see I've lost 10 lbs or more...

That's more than a gallon or 4 liters of liquid. A huge amount! Wouldn't people shrink or shrivel up like a prune, losing that much water?

 

[LOL!]

Many bathroom scales have memory:
The Best Bathroom Scales | The Wirecutter

 

[NW-Bound]

Many bathroom scales have memory:
The Best Bathroom Scales | The Wirecutter

FYI: The article does not discuss the "memory feature". However, you can scroll down and read what several commenters say about this.

 

[mpeirce]

I too have a Withings scale that uploads my weight every day - I consistently weight myself just before my morning shower. I now have almost three years of data. Obviously there is plenty of daily noise, but it is interesting to see the longer term trends. This is what it looks like:

It also measures fat. I'm not sure how accurate that is, but the trends are also interesting. Roughly similar to weight, but not exactly.

 

[AllDone]

That's more than a gallon or 4 liters of liquid. A huge amount! Wouldn't people shrink or shrivel up like a prune, losing that much water?

People are 50-60% water by weight.

 

[Lsbcal]

...
Word of advice, weight doesn't matter, the mirror is 1000 times more useful in measuring health.

+1
But apparently those scales are the real culprits.