Jolie

I don't think that is at all unusual. Many employers complete comprehensive physical exams on their candidates, with weight being a standard part of such an assessment.
I understand that most adults prefer to weigh themselves in private, but this is no different than one's primary care provider's office where weights are often done every visit.
If one is visibly overweight, that is obviously already known to the manager who extended the job offer, so it seems unlikely that an offer would be rescinded due to obesity verified by an exam in employee health.
To the OP, best of luck in your weight loss efforts! You are to be commended for trying to set a good example for your clients!