The body age assessments are 3 little fitness tests. One measureds how much weight you could press, the other had you sit on the floor with your legs extended and measured how far forward you could stretch, and I forgot the the third.
You can pay money for some testing like a VO2 Max but I wouldn't bother with that unless you are a competitive athlete.
I would expect that if you meet with a nutritionist at LTF that they will push their supplements, bars, & powders on you.