You’ve been consistent with your workouts and nutrition plan, and the number on the scale is going up. But what does that number really mean? It’s a common question in any fitness journey: am I gaining muscle, or is it just fat? Understanding the difference is crucial for making smart adjustments to your training and nutrition.
This is where the Audit pillar of our methodology comes into play. Think of your body as a laboratory and your fitness plan as an experiment. The Audit is where you analyze the data from that experiment to understand what’s working and what isn’t. Ditching the guesswork and using objective data is the key to sustainable progress. This guide will walk you through five proven methods to audit your body composition, so you can confidently know whether you’re gaining muscle or fat.
1. Take Progress Photos
Progress photos are one of the most powerful and accessible tools for tracking changes in your body composition. While the scale only shows your total body weight, photos provide a visual record of how your physique is changing. Muscle is denser than fat, so you might notice your clothes fitting better and your body looking leaner, even if your weight stays the same or increases slightly.
For the most accurate visual data, follow a consistent protocol:
- Same Time, Same Day: Take your photos at the same time of day, once a week or every two weeks. The morning, before eating or drinking, is often best.
- Consistent Lighting and Angles: Use the same location and lighting each time. Take photos from the front, back, and both sides.
- Same Attire: Wear the same or similar clothing to ensure consistency.
2. Use a Tape Measure
A simple measuring tape can provide valuable data about where you’re gaining inches. Gaining inches on your chest, arms, and legs while your waist measurement stays the same or decreases is a strong indicator of muscle gain and fat loss.
Here are some key areas to measure:
- Chest: Measure at the widest part.
- Arms: Measure the circumference of your biceps and forearms.
- Waist: Measure at the narrowest point, usually just above your belly button.
- Hips: Measure at the widest part of your buttocks.
- Thighs and Calves: Measure the circumference at the widest point of each.
Track these measurements over time. Consistent increases in your limbs and chest, paired with a stable or shrinking waistline, suggest you are successfully building muscle.
3. Consider Skinfold Calipers
Skinfold calipers are a cost-effective tool used to estimate body fat percentage by measuring the thickness of subcutaneous fat (the fat just under the skin) at specific sites on the body. While not as precise as clinical methods, they can be a reliable way to track changes in your body fat levels over time when used consistently. The key is to have the same person, preferably a trained professional, take the measurements each time to ensure accuracy. When performed correctly, skinfold calipers offer a more direct way to monitor fat loss than a scale alone. A study in the Journal of Strength and Conditioning Research found that skinfold measurements, when performed by an experienced tester, can be a reliable method for tracking changes in body composition (1).
4. Bioelectrical Impedance Analysis (BIA)
Bioelectrical Impedance Analysis (BIA) is a method used by many modern “smart scales” and handheld devices to estimate body composition. It works by sending a weak electrical current through your body and measuring the resistance. Since muscle contains more water than fat, it conducts electricity more easily.
While BIA is convenient, its accuracy can be influenced by factors like hydration levels, recent meals, and exercise. For the most reliable results, you should:
- Measure at the same time of day.
- Ensure you are consistently hydrated.
- Avoid eating, drinking, or exercising for a few hours before measuring.
Research has shown that while BIA devices may not be as accurate as clinical methods like DEXA scans, they can be useful for tracking trends over time when used under consistent conditions (2).
5. DEXA Scans: The Gold Standard
For the most accurate and detailed analysis of your body composition, a Dual-Energy X-ray Absorptiometry (DEXA) scan is considered the gold standard. A DEXA scan provides a precise breakdown of your fat mass, lean muscle mass, and bone density. While it is the most expensive option, a DEXA scan can give you an incredibly accurate baseline and allow you to track your progress with a high degree of certainty. If you are serious about optimizing your body composition, investing in a DEXA scan once or twice a year can provide invaluable data for your fitness “experiment.”
Conclusion
So, how can you tell if you’re gaining muscle or just fat? By moving beyond the scale and using a combination of these methods to Audit your progress. Progress photos, body measurements, and tools like skinfold calipers or BIA scales can provide the data you need to make informed decisions about your training and nutrition. By treating your body as a laboratory and analyzing the data, you can ensure that your hard work is leading to the results you want: more muscle and less fat.