Up-front disclaimer: I don’t expect daily weigh-ins from all of my clients, and certainly not regardless of the phase of their training. It takes a certain level of emotional detachment from the scale number (a skill worth learning) to make this worth the effort, but the insight you can gain from this process is extremely useful.
That being said, the value of daily weigh-ins is a double-edged sword. On a day-to-day basis, you are essentially just tracking your body’s adjustments and fluctuations in water retention. So an “OMG I lost 4 pounds in 2 days!” is like to be followed by a “WTF I gained 3 pounds the next 2 days??” But hey, if that happens, you’re at a net loss of 1 so you’re still winning.
What causes water retention to fluctuate?
Basically, a lot. In a perfect world of the experiment that is your body, we would have water retention as a constant, measure/track the variables (caloric intake and expenditure) and check the output (weight). What we would expect to see is a slow, even trend in the direction we’re aiming for, whether up or down.
Unfortunately water retention is anything but constant. It fluctuates seemingly according to the phases of the moon at times, though with less predictability. Here are some factors that can be considered, though this is by no means a comprehensive list:
- Hormones – I put this first because this is the thing that seems most mysterious and magical, and it should not be dismissed because of that. Changes in your hormonal makeup (short-term and long-term) will effect how your body holds on to water.
- Macronutrient intake – it is the job of carbohydrates to retain water and help seat it into muscle tissue, so higher carb intake means greater water retention. That cheat meal at the Italian restaurant? Yeah, you know what to expect the next day.
- Sodium intake – it’s well known that sodium causes water retention, but more appropriately spikes or drops in sodium intake will do this. So again, that cheat meal at the Italian restaurant with the salty tomato sauce? Uh huh.
- Water intake – again, it’s more about fluctuations in water intake. If you’re rock solid and then have a day where your intake is about half (or double) what it normally is, expect that to show up on the scale.
- Sweat output – this one is fairly obvious, but it has more to do with output in relation to intake. Double the cardio (and therefore sweat) while holding water intake steady? Expect to see changes.
What else can cause fluctuations in weigh-in numbers?
The biggest thing here that I encounter is inconsistency. If every day was the same, you would still weigh less in the AM and more in the PM (typically). If you don’t weigh yourself at consistent times, you will not see numbers that bear any relation to one another. In addition, every day is not the same, so your evening weight one day and your evening weight the next day are not easily compared. When requesting daily weigh-ins from clients, the only numbers I care about and want to see are those taken very first thing in the morning, immediately after waking. At this time we can expect the body to be in a relatively consistent state day-to-day and can begin to make sense of the data.
What’s the big picture?
To be frank, the big picture IS the big picture. Zoom out, and take everything into account. Focus on larger time intervals.
Confucius say, “she who weighs for a week measures water, she who measures for a month measures changes in lean body mass ratio”
Now I may have messed up the source or the specifics of that quote, but you get the idea. Over time, you may see a graphed result that looks something like this from one of my clients:
So, focus on that big picture – ALWAYS. Included in that chart is a week that looked like this:
139.0, 138.0, 137.0, 144.5, 141.5
You can basically see the decision that led to that spike and it’s aftermath – but also notice that things start to correct themselves right away.
Taking daily weigh-ins is helpful, but only if you can do so with an analytical mind – and understand that most of what happens in terms of large daily fluctuations can easily be explained and accounted for, if you just stop to clear your head and think about it. As humans we have a natural tendency to derive emotional satisfaction (or frustration) from a moving (or non-moving) scale. I like instead to focus on enjoying the process – the easy stuff, the hard stuff, the feeling after a great workout, etc – and know that the results will come with consistency and time. Daily weigh-ins can be helpful to gauge progress, but they are simply another tool in the arsenal.