Weight tracking is the most popular…but it’s only helpful up to a point. If you’re overweight, yes getting to a healthy BMI is important. But weight loss slows down and could even plateau as your body will fight to keep you at the weight it knows.
Also muscle weighs more volume for volume. So as you build muscle, your weight loss will appear to slow down even as you get leaner and stronger.
Use multiple parameters: inch loss, weight loss, your energy levels, how you look and carry yourself, how often you fall ill, how quickly you recover from illness and injury, your mental wellbeing.