I am trying to lose weight, more accurately I am trying to lose weight around my stomach area (overall I am a healthy weight), and I have taken to weighing myself in the morning and evening. Mostly to give my self some artificial goals.

Anyway I noticed that I weight less in the morning than I do in the evening! It's usually around 0.2/3 of a stone difference. Is this common? What causes it? If it is common, what is the correct time to weigh?


  • You may also find that your scale has intrinsic error. Weigh yourself twice in a row, and you may not get the same result. I typically weigh a few times and use the average.
    – G__
    Jun 16 '11 at 21:04
  • I've noticed that with scales that use bioelectric impedance to measure body fat, not only are you heavier in the evening, it measures less fat in the evening. I think this has to do with water retention more than anything. High amounts of water retention causes bioelectric impedance devices to count that as muscle. Jun 17 '11 at 12:07
  • But also you burn off a lot of energy and lose a lot of water while you are sleeping. Throughout the day you should be urinating any excess water you drink. So really after work should be a good time to weigh yourself.
    – Salsero69
    Jun 17 '11 at 21:02
  • So that others don't have to look it up like I did, 0.25 stone (a unit of mass) is equal to 3.5 lbs or 1.6 kg. Jun 23 '11 at 19:46

It's natural for weight to fluctuate throughout the day. Everything you eat, drink, excrete, sweat has mass and will therefore affect your scale weight.

There is no "correct" time to weigh; the most important thing is to be consistent. Pick one time of day and always weigh yourself then to try to reduce the measuring error.

I do my own weighings first thing in the morning because I think that's the most consistent time for me, since I don't have to account for variances in what I ate or drank that day.

Keep in mind that your absolute weight is a meaningless number (take BMI and other standards with a grain of salt). What's important is how your weight changes relative to what it was before given a consistent measurement process.

  • Because of what Greg says here, I always weigh myself in the morning before I step into the shower. I figure it'll give me the most consistent results. Weighing myself in the evening seems to cause a lot more variation depending on what I've eaten/done that day. Jun 16 '11 at 21:59
  • +1 for taking it with a grain of salt. Weight by itself doesn't mean much and it is better to judge by a measurement like waist circumference since that's why you're trying to improve. Jun 17 '11 at 20:11

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