QUESTION: “I just got a smart scale which measures body water percentage. Why is this important to know and what's a good percentage? I'm a 40-something female. Thanks!”
DR. NEAL: Hi, thank you so much for your question.
So many of these new-fangled scales provide us with so much more than body weight. These scales are so advanced that, in addition to telling us how much we weigh, it will calculate our body mass index (or, BMI), tell us our body fat percentage, how much lean mass we’re carrying on our bodies, and as our listener said, our body water percentage.
So, do we really need all of this information?
Is Body Water Percentage Useful?
When it comes body water percentage, I would file this in the “good to know” section. But knowing your body water percentage doesn’t provide us with information that’s all that useful.
We might initially believe that knowing our body water percentage would be helpful to tell us whether we are dehydrated. Not really. There are other, more accurate ways to determine whether we’re dehydrated. There are blood tests we could look at.
For example, there are lab tests that look at how much sodium your body is holding on to. This can help determine a person’s hydration status.
How to Know if You’re Adequately Hydrated
But beyond getting blood tests to determine whether you’re hydrated or not, looking at the color of urine is one of the best ways to determine hydration status. If your urine is a pale lemonade color, then you’re adequately hydrated.
If the urine is darker than that, you’re probably dehydrated. The darker the urine, the more dehydrated you are. If your urine is clear, you’re overhydrated – meaning, you’re probably consuming too much fluid.
So, if body water percentage isn’t the most accurate way of determining our hydration status, what’s it good for? Not a whole lot. Again, it’s basically for your information only.
Some sources claim that body water percentages for women will fluctuate between 45 and 60%, whereas adult men will fluctuate between 50 and 65%. So, for both men and women, body water percentages can range by about 15%. That’s quite a wide margin.
Where to Focus Your Attention
Instead, when it comes to choosing which information to pay attention to when using these smart scales, I would say body weight followed by body fat percentage. Of course, there’s no need to panic (or overly celebrate) when you notice small changes to either of those especially when they happen over a short period of time.
That’s because our body weight and body fat percentage change all the time, even over the course of a day. Checking body weight once a day can be helpful for weight loss and weight maintenance, but unless we’re competitive athletes, there’s no need to weigh ourselves multiple times each day. Instead, we would want to look at our progress over time. In which direction have our weight and body fat percentage changed over the past few weeks?
Over the past few months? If, in general, they’re moving in the direction you want them to, then you’re on the right track. Just don’t be surprised when there are little blips in either direction, here and there.
To increase the accuracy of these measurements, there are 2 more things you can do:
- Weigh yourself at the same time each day. If you typically weigh yourself first thing in the morning, after urinating, wearing only your pajamas then be sure to repeat this exact same pattern each time you weigh yourself.
- Don’t forget to take circumference measurements. What I mean by that is measure the areas around your waist, belly, and hips every so often. As I mentioned, sometimes the numbers we see on a scale, yes even a smart scale, aren’t always accurate. But we can use a back-up: measuring the width around the waist, belly and hips. Hand a standard tape measure to someone you trust and have them measure these 3 sites. To measure the waist, find the narrowest area between your chest bone and your belly button. To measure the belly, wrap the tape measure around your belly right at the area of the belly button. Finally, to measure the hips, find the widest area just above where your behind meets your hamstrings (this is called the gluteal fold). Ideally, do this either without wearing any clothing, or wear clothing that fits snugly. Then, stay consistent – wear the same clothing (or birthday suit) each time.
This information is far more useful than body water percentage.