Any tool that uses BMI in its algorithm has already lost the plot. Most of these tools use BMI, so they’re more fun with general results.

Hah, I would never use a fitness trainer. Recent resistance training research has changed dramatically with many nuances. I prefer to develop my training program with input and methods from Doug McGuff or Brad Schoenfeld. You don’t need to abuse yourself with long, multi-day workouts during the week, but you won’t defeat sarcopenia by simply going for walks. But I’m getting off topic.