Is BMI still considered a reliable way to diagnose obesity, or is that outdated?

It's still used, but mostly as a first-pass screening number rather than the final word. The criticism is fair in some ways. BMI doesn't distinguish muscle from fat and doesn't capture where fat is stored, which matters a lot for health risk. Current Canadian obesity guidelines frame BMI as one piece of a broader clinical assessment, not a standalone diagnosis. So it hasn't been thrown out, but it's not supposed to be used in isolation anymore. References: https://obesitycanada.ca/healthcare-professionals/adult-clinical-practice-guideline/

My doctor barely mentioned my BMI number, spent way more time on my waist measurement and bloodwork. Felt like a more useful conversation than just a number on a chart.