If you've recently undergone a DEXA scan to measure your body composition, you may have been taken aback by the results. Perhaps your body fat percentage was higher or your muscle mass lower than you anticipated based on your diet and exercise habits. Before you start doubting the accuracy of DEXA scans or feeling discouraged, consider these potential explanations for unexpected results:

1. You're comparing yourself to the wrong references Many people compare their DEXA results to general body fat percentage ranges found online. However, these ranges often don't account for age, sex, and ethnicity differences in body composition. A healthy body fat percentage for a young male athlete can be quite different than for a postmenopausal woman. Make sure you're using references that match your demographics. This article provides detailed charts to compare your DEXA results.

2. Your lean mass has changed If you've lost weight recently, a higher-than-expected body fat percentage may mean you've lost lean mass (muscle) in addition to fat. This is common if you've used an extreme calorie deficit or haven't been resistance training. On the flip side, if you've been strength training and your lean mass has increased, your body fat percentage could stay the same or even go up despite fat loss.

3. You're comparing results from different scanners Not all DEXA machines are created equal. Results can vary based on the manufacturer, model, and even individual machine calibration. If you're comparing your results to previous scans done elsewhere, the differences may be due to the equipment rather than actual changes in your body composition. For the most accurate comparisons, aim to use the same machine each time.

4. Your hydration levels and food intake weren't consistent While less of a factor with DEXA than with other body composition methods like bioelectrical impedance, your body's hydration level can still impact scan results. Drinking a lot of fluid or eating a large meal right before your DEXA may skew your numbers. For the best accuracy, try to keep your hydration and food intake consistent from scan to scan.

5. You have a unique body type or fat distribution We all carry fat differently. If you store more fat viscerally (around your organs) than the average person, a DEXA may report a higher body fat percentage than you expect based on your appearance. On the other hand, if you have very dense bones or large musculature, your lean mass may be higher than average for your weight.

The bottom line? Don't get too hung up on any single DEXA result, especially if it doesn't align with what you expected. Consider the factors above, use your results to track your progress over time, and remember that body composition is just one piece of the overall health and fitness puzzle. If you have concerns, discuss them with a knowledgeable professional who can help you interpret your individual results.

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