Body Weight vs Body Composition
What does your weight actually mean?
First and foremost, I want to discuss weight from an objective standpoint, and to do this we need to consider weight in regards to physics. Weight can be defined using the following equation:
W = F(net) = m*g
- W = weight
- F(net)= net external force
- m = mass
- g = acceleration of gravity
If we calculate someone’s weight on various planets it will differ greatly due to the fact that the coefficient of gravity is planet (or moon) dependent. If someone weighs 150 lbs. on Earth, they will weigh 25 lbs. on the Moon, 57 lbs. on Mars and 355 lbs. on Jupiter. I don’t want to drag too long on the physics of weight but I just want to emphasize how weight is just a number relative to your mass and the coefficient of gravity. So in conclusion, weight is just an objective number related to your mass and the gravity of Earth and it doesn’t mean much more other than m*g unless you permit it to have more value.
NOTE: Since most of us don’t spend an erroneous amount of time not on this planet it’s more useful to consider changes in weight to be relative to mass rather than changes in gravity.
Fat Mass vs. Muscle Mass
Next to emphasize this point, even more, let’s consider muscle mass and fat mass. On a scale fat and muscle weigh exactly the same, therefore “muscle weighs more than fat” is in fact not true. Physics people, physics! Weight will only change if you change the mass or gravity, so muscle will always weigh as much as fat just like enough feathers can weigh as much as muscle.
Rather, the densities of fat and muscle are different; the density of muscle is 1.06 g/ml and the density of fat is 0.9 g/ml. This corresponds to muscle being about 18% more dense than fat. This difference in mass can be seen in the image below.
While both clearly weigh the same on a scale it becomes glaringly obvious which one appears to be most dense. It’s for this reason someone with a lot of muscle can be deceptively small versus someone with a lot of fat appears to be much larger. This also means two individuals who weigh the same but have distinctly different body fat percentages will have starkly different physiques.
Weight & BMI
Weight loss and weight gain tracking are suitable to follow via a traditional body weight scale. However, as I am sure you are aware progress has many faces and unfortunately, progress is not always accurately tracked via a body weight scale. Weight loss could be primarily due to decreases in lean body mass or if you are fortunate enough decreases in fat. Weight gain could be due to all your hard work in the gym paying off and rewarding you with ripe gains of muscle or if you are unfortunate ripe gains of fat. Without knowing your body composition the only thing you know is the big picture, i.e. you gained weight or lost weight.
NOTE: It is entirely possible to change your body composition drastically without changing your weight.
BMI is a measurement that is based on your height and weight. The equation is as follows:
Contrary to some belief BMI is not a more accurate of as estimation of body composition, due to the fact that it generically considers only height and weight. The primary reason it is used is because it is easy to calculate and easy to compare large populations via the standard BMI grading scale.
This method is useful if you are interested in tracking the girth of a body segment and observing changes over time. This can be both useful for muscle gain or fat loss. Most commonly used is the waist measurement, however, it can also be useful to measure the girth of hips, chest, thighs, arms, etc.
Body composition testing determines the amount of lean body mass (muscle, bone, and organs) and fat mass you have. A standard body weight scale tracks your overall bodyweight, it does not provide any insight into the composition of your body and because of this, it falls grossly short when trying to track changes in your physique and composition.
Body fat is typically determined via hydrostatic weight, skinfold caliper measurements and/or bioelectrical impedance. While all of these methods vary in how they determine body fat they are all very useful when trying to determine your body’s composition.
NOTE: Those with higher body fat percentages will also take up more volume compared to their lower body fat counterparts. This means individuals who have a low body fat look lean, thin and/or more defined/toned. Furthermore, higher body fats are correlated to heightened risk for diabetes, cardiovascular disease, and high blood pressure.
Body Composition > Body Weight
Vicious Cycle of the Scale
It’s important to recognize that weight fluctuates throughout the day because of variations in hydrations, food consumption, hormones, etc. These variations in weight can result in a “gain” of weight ranging from 2-4 lbs. of weight per day. This doesn’t mean your body gained 4 lbs. of fat in one day it means you consumed food, drank water, etc.; nothing more nothing less. Additionally, your understanding as to why the number has changed isn’t affected. Are you more hydrated? Have you eaten yet? Did you just finish working out?
Weight doesn’t consider how you feel or what you did that day because it is unbiased. By definition it will always be a measurement of mass*gravity at the point in time it is measured. Your power and strength are determined by what you do with the number and how you let it affect you. If you repeatedly check your weight throughout the day then the power you have over the scale is minute.
A lot of people, myself include sometimes, tend to get obsessive with the numbers (i.e. body weight). First and foremost, don’t ever let this number define you. As we already outlined weight is only a number; you and you alone define its value. If you let the numbers on the scale consume you then you will never find peace with what you see. Moreover, weight doesn’t delve into what that number actually means. Is 25% of that weight fat mass or is 10% of that weight fat mass? Unless you understand your body composition you don’t know.
A client I had been working with for about 4 months was able to lose 17 lbs. of fat and gained 15 lbs. of muscle. A remarkable feat if you consider his change in body composition. However, if we look at it from the objective view of the scale he only lost 2 lbs. All that sweat and hard work for a measly 2 lbs. of weight loss seems like he was cheated of both his time and money. However, because he was having his body composition tested we were able to determine that his success what much more remarkable than what was on a body weight scale.
We can accomplish so much more by having more knowledge and more understanding. This depth of knowledge increases when you understand what is changing, where you started, and how far you’ve come. A body weight scale merely touches the surface of body composition and when you get your body composition tested you are able to delve further into understanding your body and the changes that are occurring.
Tips for more accurate testing
Body Weight Scale
While I have been primarily speaking ill of weight it can still sometimes be useful to track. For those who are adamant about tracking your weight here are a few tips for how to increase the accuracy of this measurement.
- Test only first things in the morning before you do anything else (i.e. eat or drink)
- Prior to stepping onto the scale use the restroom and make this a habit prior to weighing yourself.
- Weigh yourself preferably once a week
- If this isn’t frequent enough for you, slowly increase the days between weigh-ins till you are comfortable with once per week
- Don’t freak out if the number isn’t going in the direction you want. Remember changes in composition are more accurate than changes in body weight
Bioelectrical Impedance Scale
If you are using a bioelectrical impedance scales it is better to test later in the day (i.e. afternoon/evening). This is because when you first wake up your body is typically dehydrated, meaning your muscles will have less fluid in them. Therefore your lean muscle mass will be lower and conversely, this means your body fat will be higher. Additionally, it’s best to measure 2-3 hours after your last meal, shower or workout to improve accuracy. Depending on the brand you use the accuracy can be a few percentage high or low. Regardless, track changes in your body fat relative to the scale you consistently use.
Qualitative Progress Tracking
All of the methods for progress tracking we have been discussing till this point have been quantitative. While quantitative measurements are good for understanding your composition they don’t do much in the way of depicting how your look or feel. Making note of changes in how your clothes fit, your energy levels, your sleep patterns, or how you look in a mirror or picture can be very useful qualitative measurements that you can write down in a journal or your phone.
One of the most useful things you can do is take a picture of yourself. While you may not like what you see in the mirror (or picture) initially this method is used to visually observe changes over time. For this to happen you need to have a starting point for your progress pictures.
Just like how weight scale changes don’t happen overnight neither does progress in your pictures; they both take consistency and hard work. This means taking a progress picture every day is not in your best interest if you want to see stark differences in your visual progress.
In order to see more dramatic changes in your visual physique take pictures on the same day of the month (i.e. the 14th of every month) and use multiple angles (i.e. front, back, side, etc.) to see transformation results clearly.
Remember one pound of fat is equal to one pound of muscle. Fat occupies more space making those with a higher body fat percentage appear to be larger. Conversely, those with lower body fats and larger amounts of lean mass will appear to be leaner and more toned/defined. Having larger amounts of muscle also comes with other benefits such as improved insulin sensitivity and increase metabolic efficiency; this means gaining muscle helps with losing fat.
When you start your program make sure you don’t set yourself up for failure. Tracking only your body weight leaves you skimming only the surface of your body composition. Tracking your body fat is gives you a more detailed look into your weight and allows you to better understand the composition of your physique. While the numbers are important don’t let them consume you, let them motivate you to make changes happen.
Moreover, the more you know the better you are able to see changes and track success. Regarding your body composition, this means taking progress pictures, tracking circumference measurements and your body fat on a monthly basis.
Reach out to others for help, whether it is your friends, family or a fitness/health professional, like myself. Understanding how to properly set up your exercise and nutrition programs to accomplish your goals not only expedites the time it takes to reach them, but also allows you to spend less time worrying about getting things right and more time ensuring you get them right.
Remember success does not follow a straight line it takes both accomplishment and failure to get there. In the long-term, if you keep doing enough to succeed then you will outweigh any failure you may have faced. Changing your body composition is not only correlated to changes in weight or mass but is equally accompanied by making appropriate lifestyle changes that lead you to the path of success.