Does anyone know anything about the scales that show body fat %, muscle %, weight, some even claim to show water retention?

I’m just curious because I’d really like a way to track muscle vs fat.

Also, I have a family member who goes on crazy 500 calorie diets once or twice a year to “trim down” from the holidays.

But she’s curious to see if she loses muscle during her diets and I’d honestly like to see as well.