The Scale Is A Tool - You’ve Got To Know How to Use It.

The humble body weight scale cops a lot of criticism. I completely agree that it is far from a perfect tool and is limited in it’s utility. However, it does provide immensely valuable data. The problem that most people run in to that causes them to slam the scales and decide that they are useless is that the user does not know how to interpret the data that the scale provides.

Because of this, the scenario that we’ll commonly see is this: for weeks their training is going extremely well. They’re getting stronger and progressing in the gym. Their nutrition has been great and they’ve been honest and disciplined. They feel better and wake up more energised each day. Their clothes fit better, they’re happy and they're confident. Then, they step on the scale, see their weight hasn’t changed or worse, has gone up and they are instantly defeated. They do their best to hold back their disappointment as if they’ve failed. It’s all been for nothing. All of my hard work, nothing.

What they fail to see, recognise or understand is that your bodyweight will fluctuate every single day based on a multitude of factors that are beyond changes in body fat: salt consumption, carbohydrate consumption, volume of food consumed, water intake, sweat, exercise, the menstrual cycle, meal timing relative to weigh in time, sleep timing, bowel movements, just to name a few. More often than not, day to day changes are just fluctuations in the water content of your body and therefore, are not indicative of your effort or progress.

 Let me break this down a little bit.

Salt consumption.

Our kidneys and a team of hormones are largely responsible for regulating the salt and water balance of our body. When we eat salty foods, some of these hormones are up-regulated, causing us to hold more fluid to dissolve the salt and maintain a constant salt balance. If this didn’t happen, our fluid balance would be all messed up causing big, big problems. Obviously water weighs something (pick up your water bottle for confirmation if required) so when you consume more salt, your body weight will increase due to the increased water retention.

Carbohydrate consumption.

For every one gram of carbohydrate in our body, we hold 3-4g of water. Therefore, if last night’s dinner was a big serve of pasta yielding 200g of carbohydrates, your body weight is now pushed up by not only the volume of the food, but also the 600-800g of water that the carbohydrates are holding on to. Again, not body fat. Just water.

Volume of food consumed

Food weighs something outside of our body. It also weighs something inside our body. Therefore, if you consume a large volume of food, like we do every single day, body weight will go up. This is largely why we are heavier at night than we are in the morning. Food is not immediately completely digested. It does sit in our digestive tract for some time and during this time, it still weighs something.

Meal timing relative to weigh in timing.

We are generally lightest in the morning as we are coming off the back of an 8-12 hour fast (depending on what time you ate dinner and how long you slept). If you have a late dinner and/or if you wake up and weigh in early, you will likely be heavier. Conversely, if you eat an early dinner and/or sleep and weigh in late, you will likely weigh lighter. This also means that if you have irregular meal and sleep times, you’ll likely see larger scale fluctuations than someone who eats and weighs at the same time every day. As a more obvious example, if you weigh yourself before a meal and after a meal, when do you think you will weigh more or less?

Water intake.

The exact same can be said about water. Water weighs something outside of our body. It also weighs something inside our body. Therefore, when you drink water, body weight goes up. Again, this contributes to why we are heavier at night than we are in the morning. As an experiment, weigh yourself then drink a bottle of water and jump on the scale again. You obviously haven’t gained body fat. You’ve only consumed water.

Dehydration.

When we consume inadequate water, the hormones involved in fluid balance cause us to hold on to any water that is in our body to dilute the salt and maintain homeostasis. Therefore, while in the immediate term, water consumption will push our weight up; over hours/days, inadequate water consumption can also push our weight up as our body fights to store what water does come in.

Bowel movements.

You will be lighter after you use the bathroom. You’re welcome to test this yourself too.

Sweat.

When we sweat, fluid is lost to help us cool the body via evaporation. Fluid lost = water weight down = scale weight down. This is why using a sauna will cause your body weight to drop. Saunas are not a miracle fat loss tool; they just make you sweat. And all of that “weight” will come right back on as soon as you rehydrate.

Exercise.

As above, when we sweat, fluid content in the body decreases. But we often rehydrate by drinking water while we exercise, which will either maintain or increase body water content, depending on the ratio of water in to water out. Further to this, when we exercise, specifically when we resistance train, we cause micro tears in the muscle fibers (this isn’t a bad thing). To repair these micro tears, there is an increase in blood flow to the area to deliver substances that facilitate healing. The body retains fluid in the area until the tears are healed. Since blood is 90% water, we may see an increase in fluid retention in the body immediately post exercise.

Menstrual cycle.

The hormonal changes that regulate the menstrual cycle also regulate fluid balance at various stages throughout the cycle. In the days leading up to menstruation, estrogen and progesterone decrease, initiating menstruation and also causing the tissues of the body to accumulate and hold more water. This is why we bloat. You may also experience fluid retention during ovulation, around days 11-14 of your cycle.

An example for you. Me. This is my own body weight data for a two week period.

At the start of the fortnight, Monday - Saturday my weight was trending downward nicely. On Saturday, I ate a burrito for lunch and for dinner, a whole pizza, a cider and a choc peanut butter tart. These foods are all high in salt and carbohydrates. Therefore, on Sunday, my weight increased by 600g. I did not gain 600g of fat overnight. On Monday, I returned to eating normally, drank more water and trained as normal, so my body weight began to drop as I dropped fluid. Tuesday was the first day of my cycle and I bloat quite a lot. So, my weight went up another 400g. Again, not fat. This is very common in females at that time of the month. And you will see as the week went on, my body weight began trending back down until again it was Saturday and I enjoyed another indulgent meal as part of my healthy social life.

Imagine if I did not have this knowledge around fluid balance and weighed only on Friday of week one and Tuesday of week two. We have all done this.

So how can we better measure body composition progress?

Weigh regularly.

Instead of weighing only once per week, weigh 3-7 days per week. This will enable you to see day to day changes and learn to associate these with what causes them.

Take weekly averages.

Weigh 3-7 days per week, calculate your average weight across a seven-day period and compare weekly averages instead of your weight day to day. This will take in to account the fluctuations we see across a weekly period, eg exercise on weekdays and pizza on Saturdays.

Weigh at the same time every day.

This will control some of the daily fluctuations and provide a more accurate reading. I recommend weighing first thing in the morning, on an empty stomach, after using the bathroom.

Always use the same scales.

Most scales are not 100% accurate, so comparing your weight on two different scales is completely useless and oftentimes highly stress inducing. Use the same scale every time you weigh.

Track trends over time.

Instead of looking at immediate changes in body weight, ie your weight today V yesterday or this week V last week, look at how your body weight has trended over the last one, three or six months.

Track your menstrual cycle.

Since we know that our menstrual cycle significantly effects scale weight, compare your weight at the same point of your cycle. Ie, only compare week one averages to week one averages.

Take notes analysing acute body weight changes.

When you see that your body weight has increased or decreased from the preceding days, take notes that explain the variables that may have contributed to these changes. This will help you in being able to objectively appraise your body weight over time so that you have a lesser emotional response to future fluctuations.

Use multiple measures

Don’t rely solely on the scales to measure body composition change. Couple this with taking circumference measurements like your waist and hip, taking progress photos (always in the same clothes, with the same lighting and angles) and noting how your clothes fit.

And remember, your body weight will always fluctuate. Your body is a dynamic, ever changing machine, working 24/7 to keep you alive and in good health. Please for the love of god, give it some space to do it's thing.