If you say you want to lose weight, you’ll probably measure progress by stepping on a scale. But in truth, what you’re trying to lose is fat, and the number on the scale may not reflect that. There are many ways to measure your body fat percentage, but they all come with different levels of (in)accuracy.
Stay away from impedance measurement – the reliability is simply too low to be valuable at any level (but specifically for the more inexpensive models found in gyms). There’s a reason we still teach skinfold measurement in university classes: while it’s not perfect, it’s accurate enough for non-elite athletes and the average person.