Why Body Fat Percentage doesn't tell the entire story

Measuring and tracking body fat is an important method for evaluating health. However, it's important to keep in mind that body fat percentage (Percent Body Fat / PBF) doesn't necessarily tell the entire story when it comes to body composition and overall health!

 

It's a common story. You begin a fitness program at the gym, and work hard training for an hour 3-4 times a week. You might be seeing some slight improvement in the mirror, but when you check your PBF, you find that it's stayed the same, or even increased! What happened?

Assuming you've been eating and training properly, you've likely gained weight. In this case, muscle mass has increased together with fat mass. A caloric surplus is recommended to build muscle, and it's normal for you to gain a bit of fat together with muscle during this time - this is commonly referred to as "bulking", and it's a commonly recommended way to build muscle.

 

 

Losing weight typically requires you to limit caloric intake, so you're using more energy than you're taking in each day. Most people will typically go through this phase after completing their "bulking" phase, as they want to get rid of extra body fat that was gained in the muscle-building process.

 

However, if your PBF has remained about the same despite losing weight, then the reason is you're losing muscle mass at the same time.

 

It's almost inevitable that you'll lose a bit of muscle together with fat when you cut calories and lose weight. However, maintaining sufficient nutrient intake (such as protein, even as you decrease carbohydrates) while continuing a maintenance level of training is still needed to avoid losing your hard-earned "gains".

 

 

If your PBF is normal but your weight and BMI is noticeably low, then the reason is simple - you don't have enough muscle!

Although the health risks that come with being obese or excessively overweight are fairly well known, being severely underweight can have associated health risks as well, even if body fat is relatively normal!

 

While it's a common belief that someone who is slim is automatically more healthy than someone carrying around excess fat, having insufficient muscle mass is a common problem among underweight people, which can eventually lead to various other health conditions such as sarcopenia!

 

If someone's body fat is normal but their weight is low, we recommend checking the SMI (Skeletal Muscle Index) / ASMI (Appendicular Skeletal Muscle Index) and comparing it with the cut-off ranges for sarcopenia. If it is lower than the cut-off limit, then it is likely their muscle level is too low and needs to be increased!

 

 

If your device provides muscle measurements in addition to body fat, that's an improvement over traditional "body fat scales", allowing you to see if muscle levels are too low and avoiding the shortcomings mentioned above.

 

However, *where* your muscle is distributed also matters as well. It's actually surprisingly common for people to have more developed upper bodies compared to the lower body, or with a noticeable left-right imbalance, which can increase the risk of injury.

In the example above, we see that this person's overall muscle-fat balance is quite good, with higher-than-normal Skeletal Muscle Mass, and a healthy PBF. However, when we look at the segmental results, their upper body is much more developed compared to their lower body.

 

 

Ultimately, while PBF is an important indicator, it is only one snapshot of overall health, and relying entirely on it can provide an incomplete or even misleading understanding.

 

If you have access to a full-body analyzer like the MA601 which provides segmental fat and muscle results, that will give you  important additional detail, helping you understand your body and health status more accurately!