The humble weighing scales have long been one of the most commonly used tools to track weight loss and determine dietary success.
However, the number on the scale can be deceiving...
The truth is, your weight can fluctuate drastically for numerous reasons aside from gaining or losing body fat. In other words, dropping pounds on the scale doesn't always mean you're getting leaner or improving your health, and seeing the number rise doesn't mean your hard efforts have gone to waste.
In this article, we’ll explore the various factors that can influence your scale weight, and we’ll share other metrics you can track for a more accurate story of your health and body composition.
Does Keto Lead to Rapid Fat Loss?
Yes and no.
Many people report that they lose several pounds in weight during the first week of Keto, but is this all body fat?
While some fat loss may occur, in all likelihood, this initial weight loss is largely down to the body running through its glycogen stores in response to carbohydrate restriction and the consumption of fat in its place.
It’s important to note that each gram of stored glycogen in the body is bound to approximately 3 grams of water [*]. Studies suggest that the average human stores approximately 100 g of glycogen in the liver and between 350-700 g of glycogen in muscle tissues [*].
The bottom line: While a Keto diet can lead to a reduction in body fat, it's unlikely that this is the main cause of any initial rapid weight loss. Therefore, relying solely on the scale isn't the most accurate way to track how well your body is responding to a change in nutrition - particularly through a low-carb diet.
Other Ways the Scales Lie to You…
1. Weight fluctuations throughout the day
A daily weight fluctuation of 5-6 pounds is completely normal [*], largely due to variations in food intake and water consumption.
For a more accurate representation of your weight change, you should weigh yourself at the exact same time each day. First thing in the morning after a glass of water is a good way to control the variables as best you can.
2. Gaining muscle mass
If you're exercising regularly, performing resistance training, and consuming adequate protein, you may be gaining muscle and increasing bone density [*].
This could mean your weight seems to increase or stays the same week to week, which can be disheartening if you're only using the scale as an indicator of your progress.
“A pound of fat takes up almost twice as much space as a pound of muscle, because muscle tissue is denser than fat. So you lose a little weight, but gain a little muscle on a hypertrophy program, and the scale doesn’t know the difference.”
Dr. Tracy Tylka [*]
3. Post-workout weight gain
Although exercise is a key part of the picture for sustainable weight loss, in the short term it can cause the scales to go in the other direction.
Muscle damage, swelling, and increased glycogen storage may lead to apparent weight gain after intense exercise [*]. Don't sweat it though - this is only a temporary response and will not impact your long-term weight loss goals.
4. Hormonal changes
Many females report a fluctuation in weight of up to 3-6 pounds during their menstrual cycle. This is completely normal and thought to be largely due to hormonal fluctuations and changes in water weight [*].
5. Processed foods
Having a cheat meal or two is nothing to beat yourself up about, but the higher salt or carb content found in most processed foods can lead to water retention and apparent weight gain [*].
6. Gastric emptying
It can take anywhere between 2-5 days for the food you eat to travel through your digestive system and leave the body [*]. How regular you are on any given day can impact your scale weight quite considerably.
7. Measurement errors
While most home digital weighing scales are fairly precise, dial scales are known to be less so, resulting in abnormal weight fluctuations [*]. Sticking with digital and ensuring you zero the scale before use may improve precision.
Why the Scale (and Your BMI) Isn't Reflective of Your Overall Health
Eating a balanced diet, exercising regularly, crash dieting, dehydration, and losing a limb all have one thing in common:
They can all result in a loss of body weight.
However, that doesn't mean they’re all sensible options to pursue.
In other words:
Having a lower body weight doesn't always = better health outcomes.
Relying on a single number like this doesn't give an accurate representation of the whole picture when it comes to your health or body composition. It simply provides a snapshot of your relationship with gravity.
The same could be said for Body Mass Index, BMI for short.
The BMI calculation involves dividing your weight in kilograms by your height in meters squared.
The resulting value is then used as an indication as to whether or not you are at a healthy weight [*]:
But as we explored above, there are various factors that can impact your weight at any given time. As muscle tissue is more dense than fat, many active individuals with a higher percentage of muscle mass end up with a BMI that indicates they are overweight or obese.
And at the other end of the spectrum, you can have a BMI value that is not classed overweight or obese, but still have a body fat percentage that is deemed “overfat”. Research suggests this could include up to 40% of normal-weight individuals [*], placing them at an increased risk of developing various chronic diseases.
So if weight and BMI alone are not all that helpful, what should you use instead?
Better Ways to Track Your Weight Loss & Wellbeing
The scales can be a useful tool in some cases, but the following measures can help you more accurately track the impact of your diet and lifestyle choices on your body composition and wellbeing:
1. Body Fat Percentage
A study published in the Annals of Internal Medicine concluded that keeping body fat low may be more important than maintaining a low body mass index (BMI) [*].
There are a few ways to keep track of this metric:
- DEXA Scan. One of the most accurate ways to determine your body fat and lean mass percentages, along with bone density. The downside is the cost (~$125 a scan) and that you have to visit a medical facility.
- Skin Calipers. Taking skinfold measurements at various parts of the body can be reflective of body fat percentage. They are inexpensive, but there’s a high degree of error if not carried out by a trained professional.
- Bioelectrical Impedance Scales. Many bathroom scales now come with body fat measurements via bioelectrical impedance analysis. This measures the time it takes for an electrical signal to travel through your body. Accuracy can vary based on hydration, so it’s important to carry out the measurements at a similar time of day, ideally at similar hydration levels [*].
- Photo Comparisons. Various charts exist showing people at various levels of body fat. Although not the most accurate representation, they can be used as a rough comparison.
The American Council on Exercise [*] suggests the following body fat percentage norms:
2. Waist to Hip Ratio
Waist circumference and waist to hip ratio are two measures that can be done easily at home and provide a decent insight into your body composition and health status.
Studies suggest that waist circumference has a stronger association with health risks than BMI [*].
A report from the World Health Organization states that a waist to hip ratio of more than 0.85 for women and 0.9 for men may significantly increase the risk for obesity-related illnesses, including heart disease [*].
To measure your hip to waist ratio:
- Waist: stand up straight and exhale, then use a tape measure to record the smallest circumference around your waist, typically just above the belly button.
- Hips: measure the largest circumference around your hips, which is typically the widest part of your buttocks.
- Determine your waist to hip ratio by dividing your waist value by your hip value.
3. Visual Changes
Taking a step away from the numbers and tracking more visual metrics can also be an effective way to keep tabs on your body composition.
Progress photos taken from the front, back, and side under the same lighting conditions can offer some insight. Comparing photos every week or month will help you see changes that may have otherwise gone unnoticed by simply looking in the mirror or tracking your scale weight.
Similarly, the way a certain piece of clothing fits can also be a useful indicator as to how your body composition or weight distribution changes over time.
4. Mental & Emotional Habits
Although losing weight or maintaining a lean physique is a common goal and there are clear health benefits to not carrying excess body fat, it's important to recognize that there’s more to life than looking a certain way.
Striving to live up to an unrealistic ‘ideal’ appearance that’s largely determined by the media is a surefire way to feel bad about yourself. In fact, as stated by a report by the Mental Health Foundation [*]:
“Higher body dissatisfaction is associated with a poorer quality of life, psychological distress and the risk of unhealthy eating behaviors and eating disorders.”
If you tend towards negative thoughts and behavior patterns around weight loss, or you have an unhealthy relationship with tracking metrics, you may benefit from switching the focus to more health-centered measures.
Through daily or weekly journaling, you can keep tabs on:
- Your energy levels throughout the day.
- Your daily activity levels.
- Your overall mood and self-esteem.
- How many pieces of fresh fruit and veg you consumed per day.
You may find that focussing less on the outcome and more on the process, and how you feel day to day, leaves you with a greater sense of satisfaction long-term.
Healthy Weight Loss is a Slow & Steady Process
It can be tempting to hone in on one number when you're looking to lose fat or support your wellbeing. The reality is, your scale weight is just one piece of the puzzle.
By all means, zoom in now and again, but for the most part, try to keep the bigger picture in mind.
Know that progress will not always be linear. There will always be natural fluctuations, so consistent action and patience are super important.
And on top of that, try to keep tabs on metrics that are more reflective of your fat loss and wellbeing, and remember that you’re more than just a number.