Body weight is one of the most important variables we can track to gauge if we’re actually getting to our goal. However, also remember that tracking your body weight can be stressful and in some cases cause more problems than it’s worth.
If you are someone who just wants to get to a healthier body fat, you will very likely be able to get there without the scale. If you focus on changing your nutritional habits, you might find you get leaner without having to regularly quantify your body weight changes.
If you determine that your current goal is to lose 0.5kg of your body weight per week, how do you measure this loss in a weekly time period if you only weigh-in on Saturdays under very different conditions?
You can’t. At least not accurately!
What I recommend is to have a daily weigh-in first thing in the morning, after you use the bathroom, before you eat or drink anything, nude, and record the number. It’s not that we care about the single day’s weigh-in (we don’t, and focusing too much on your daily weight can drive you crazy, rather it’s that you’re going to use your daily weigh-ins to generate an average weight for the week.
Once you have your average, the goal is to compare your average weight from one week to the next. Over a week, averages will flatten out daily fluctuations in body weight and give you a workable, reliable number.
It is totally normal for your body weight to fluctuate 1–2% on a daily basis due to shifts in water (sometimes more for some people). This is caused by day-to-day fluctuations in food intake, sodium intake, alcohol, and stress hormones, or from hormonal shifts during certain phases of a menstrual cycle (among other things).
But what you’ll notice is that when you get a weekly average, that number is much less variable and much more comparable when looking at a previous week’s average. These averages become even more consistent if you perform the weigh-ins as I recommend (first thing in the morning, nude, after you use the bathroom before you eat or drink anything). Additionally, the weigh-ins will be more reliable when your diet is more consistent.
Even if you do find that there is some variation comparing one week to the next, you will be able to see those trends and you can decide to track averages over 14 days if needed to ensure you can tell if you fall within the coming guidelines for body weight change.
In fact, for most people I recommend not making changes until you have 2–3 weeks of averages to compare, to really smooth out these numbers and show you the real trends.