The scale is fickle: We lose weight when we pee or when we do a sweaty workout. We gain weight when we eat or drink or put on a sweater. But how much does that kind of fluctuation really impact the numbers we see? I weighed myself 15 times in one day to find out.
Illustration by Elena Scotti/Lifehacker/GMG, photos via Getty Images
63.6kg at 9:16AM: I step on the scale for the first time. I've just woken up. I'm wearing light pyjamas.
63kg at 9:19AM: After going to the bathroom. Apparently my bladder can hold at least 600g of urine. Well, that's a new thing I learned.
64.2kg at 9:23AM: Fully dressed, in jeans and shoes. This is how I'll weigh myself for the rest of the day, because I'm not getting naked every time I want to step on the scale.
65kg at 9:24AM: Oops, forgot my hoodie. That's 2kg of clothing in total.
66kg at 10:35AM: After breakfast, which apparently weighed 1kg including beverages.
65.5kg at 11:45AM: After pooping. That's a 500g poop.
66.7kg at 2:23PM: After late lunch/early dinner. Full bladder.
66.1kg at 2:28PM: Peed again, 600g.
65.8kg at 5:58PM: Didn't do anything special in the last few hours. Lost 300g!
65.5kg at 6:57PM: Ditto. Another 300g gone. Losing weight is easy!
64.6kg at 7:04PM: In workout clothes and hoodie. I'm back to my pre-breakfast weight. Now it's time for a Nike Training Club workout (the one they call "Lifted by Lunges").
64.5kg at 7:45PM: After a 30-minute workout. I drank around 500mL of water (which weighs 500g) and apparently sweated the same amount.
63.5kg at 8:15PM: Naked, after shower, damp hair. This is the least I'll weigh all evening.
64.8kg at 11:07PM: One last weigh-in wearing regular clothes.
64.6kg at 11:09PM: In my pyjamas. We typically lose a few kilos while we sleep. I was down to 63.2kg the next morning, within half a kilo of my initial weigh-in.
I think of myself as a 64kg person, but my highest weight was 66.7kg. My lowest was 63kg. Note that most of the daytime weights included about 2kg of clothes — so they aren't my "true" weight, but they're what I would see if I stepped on a scale during the day. I know you've seen that scale at the gym, or maybe you have one in your bathroom that sort of taunts you as you sit on the toilet looking at it.
I knew I'd see fluctuations, but I was surprised at how big they were. We're often told to weigh ourselves first thing in the morning, after going to the bathroom but before eating breakfast. That corresponds to my lowest weight in the experiment, and it makes sense that it would also be the most consistent. Even this number will change from day to day, of course, depending on things like exactly how hydrated you are.