Ooh snarky

Everything that's the same weight weighs the same... I don't think you're understanding why people say this.

If you eat at a calorie deficit for a week and lose 2 lbs of fat the scale will show you that. But if you workout and gain muscle during that time, even a relatively small (volume-wise) amount of muscle will minimize the progress you see on the scale. So the scale may show that you lost 1.5lbs overall, but it doesn't break down that you lost 2 lbs of fat and gained .5 lb of muscle. Because fat takes up more room than muscle, measurements can show you that you're smaller overall. Even if that isn't the sole reason you're seeing this discrepancy between your expectations and your results, it's always a good thing to keep in mind.