The Ultimate Guide to Measuring Body Fat Percentage: Methods, Benefits, and Who Should Do It
I have an embarrassing confession to make: the idea for this blog was inspired by a trashy Netflix show called STRONG. The show pairs ten top trainers with participants aiming to lose weight and get fit, and they compete in various challenges. Despite its entertainment value, it's not exactly a reliable source for workout plans. What caught my attention, though, was the transformation segment at the end of each episode, where they reveal the participants weight loss, clothing size reduction, and changes in body fat percentage. As someone who has measured the body fat percentage of many clients and athletes, I found some of the quoted figures dubious, sparking this discussion on the complexities and importance of measuring body fat percentage (BF%).
Why Measure Body Fat Percentage?
For the general population and recreational athletes, body fat percentage often seems like a vanity metric, something to post on Instagram. While there's nothing wrong with that, I advise considering whether you're truly getting your money's worth. This isn't to say BF% is a pointless measurement—it can be incredibly valuable, especially when used correctly.
In sports, body composition is often linked to performance. Knowing your BF% can help you make informed decisions about your training and nutrition to optimize performance. For those on a weight loss journey, it’s a quantifiable measure of progress. I’m a big advocate for having measurable goals—how else can you track improvement?
BF% is also extensively used in research to explore the impact of body composition on performance and to evaluate the success of nutritional interventions. So, it’s definitely useful, but context matters.
Who Should Measure Their Body Fat Percentage?
If you're a recreational athlete, getting your BF% measured might not be necessary. While it can guide your fat loss or muscle gain journey, other, more cost-effective methods can track progress accurately. Accurate BF% measurements become more crucial when you’re pushing the limits of performance or aesthetics.
For recreational athletes, tracking a trend is often more important than knowing an exact number. Even less accurate methods like bioimpedance scales can be useful for this purpose if used consistently under the same conditions.
Elite athletes might need more precise measurements to fine-tune their training and nutrition. However, it’s important to note that optimal body composition varies between individuals and sports. For example, endurance runners benefit from a lower BF% to reduce excess weight during long runs, but too low a BF% can have health and performance implications.
From my experience with CrossFit athletes, the optimal BF% range for elite males is around 10-15% and for females, 15-25%. Remember, these numbers can vary significantly between individuals and sports.
How to Measure Body Fat Percentage
Let’s explore the most common methods to measure BF%, their flaws, and even the gold standards that aren’t perfect.
Bioimpedance
Bioimpedance is one of the most common and accessible methods, found in many digital scales. It works by passing a small electrical current through the body and measuring the resistance (impedance). The method estimates fat-free mass based on the assumption that 73% of fat-free mass is water. While it's easy and cheap, it relies on many assumptions that often aren't met in real-world conditions. Hydration status and meal timing can significantly affect accuracy. However, bioimpedance can be useful for tracking trends if used consistently under the same conditions.
Skinfold Calipers and Ultrasound
Skinfold calipers and ultrasound measure the thickness of fat at various body sites to estimate overall BF%. The accuracy and reliability of these methods depend heavily on the practitioner's skill. The International Society for the Advancement of Kinanthropometry (ISAK) provides certification to ensure practitioners can perform accurate measurements. If you’re getting your BF% tested, make sure the practitioner is ISAK certified.
Calipers are often seen as intrusive because they involve pinching the skin and fat, while ultrasound offers a non-invasive alternative and can measure tissue layer thickness more accurately. Despite this, both methods have limitations and rely on practitioner skill.
DEXA (Dual-Energy X-Ray Absorptiometry)
DEXA scans are often considered the gold standard for measuring BF%. They use two X-rays of different energies to scan the body, with one energy absorbed more by fat than the other. The resulting data allows computer software to construct a detailed image of body tissues. While highly accurate, DEXA scans are expensive and typically used in clinical settings or by professional athletes. They also require trained technicians, and results can’t be directly compared between different DEXA machines due to a lack of standardization.
Conclusion
Before you decide to measure your body fat percentage, ask yourself: do you really need it? If you're looking to track progress and can accept some inaccuracy, bioimpedance might suffice. If you need precise measurements for specific goals, ensure the practitioner is qualified and understand that even the best methods have limitations. And if you ever get the chance to have a DEXA scan, use the information wisely. Measure with purpose, let the data guide you, and always tailor your approach to your unique needs and goals.
Want Help Cutting Body Fat?
I’m a performance nutritionist (MSc, ANutr) with over 7 years experience working with high performers and athletes to reach their goals. Check out how I can help you here.
